ASHS 2025 Conference

Peach (Prunus persica) production in the southeastern United States, particularly in South Carolina, is challenged by high humidity, variable chill accumulation, and persistent disease pressure – especially from bacterial spot (Xanthomonas campestris pv. pruni) adn brown rot (Monilinia spp.). In response, Clemson University reestablished its peach breeding program in 2008 with the goal of developing fresh-market cultivars adapted to this region’s demanding conditions. After more than a decade of field evaluation and selection, three new cultivars have been released under the ‘CaroRes’ and ‘EveRes’ series: ‘CaroRes Wonder’ (USPP 36,072), ‘EveRes Ruby’ (USPP 36,112), and ‘CaroRes Delight’ (USPP approved). The ‘CaroRes’ name signifies both Clemson’s South Carolina origin and disease resistance, while ‘EveRes’ identifies cultivars that combine disease tolerance with a slow-softening phenotype, allowing fruit to remain firm on the tree longer than standard melting types. All three cultivars are vigorous, productive, and well-suited to southeastern U.S. orchard systems. The cultivars exhibit high fruit tolerance to bacterial spot. In replicated trials, they demonstrated reliable productivity and good pack-out percentages with minimal split pit incidence. The fruits are large, round, and clingstone, with light pubescence and a high percentage of red skin blush, ranging from 80% to 95%. All cultivars have yellow melting flesh, though ‘EveRes Ruby’ exhibits a firm, crisp texture at harvest that gradually softens over several days at room temperature, enhancing postharvest handling and shelf life. ‘CaroRes Wonder’ and ‘CaroRes Delight’ ripen in the early season, while ‘EveRes Ruby’ ripens in the early to midseason. Across all three cultivars, fruit quality evaluations consistently rated flavor, texture, and appearance highly. These releases provide new options for growers seeking disease-tolerant cultivars with excellent fruit quality, reliable performance, and adaptability to the environmental challenges of the Southeast. Their unique combination of field resilience, consumer appeal, and handling advantages makes them strong candidates for fresh-market production. Trees are available through licensed TN nurseries, including Cumberland Valley Nurseries and Vaughan Nursery.

The production of blackberry, a valuable fruit crop, is primarily limited to USDA Zones 5 and higher. However, wild species such as Rubus allegheniensis, R. alumnus, and R. rosa are widespread from Zones 5 through Zone 3a in Minnesota and Wisconsin. Native species are a valuable, untapped genetic resource, which could provide both hardiness for production in colder areas with short growing seasons and resilience to pests, diseases, and climate change for warmer areas. The use of native species for breeding has been limited as little research has been conducted to date. To access the utility of this germplasm, propagation protocols developed for them will need to be established. Because sexual and vegetative propagation requirements for the genus Rubus vary widely depending on taxa and genotype, this research aims to evaluate protocols specific to these species. Canes were collected from 24 northern locations to test rooting of softwood cuttings with either IBA and NAAm auxin treatments in early spring and again in summer. Additional canes were collected from one location to test the rooting of dormant cuttings using IBA and bottom heat to stimulate root growth. Results indicate that the suitability of softwood cuttings for propagation is dependent on the section of the genus, with samples over 30% of samples from section Procumbentes (dewberries) rooting, while sections Arguti, Canadenses, Rubus (highbush blackberries), Setosi (bristleberries), or Ideaobatus (raspberries) all had under 10% rooting rates. In addition, seeds were collected from 5 locations to test germination protocols. Seeds were divided between two stratification treatments(20°C control and a six-month at 4°C). Within those, seeds received either no scarification, physical scarification, 30 minute acid scarification, or 3 hour acid scarification treatments. The 30 minute acid scarified seeds were also divided between a control and aqueous smoke solution treatment. Results from germination tests indicated that long acidic scarification treatments do not result in increased germination at six months.

Papaya ringspot virus (PRSV) is a devastating pathogen found throughout the tropics and subtropics. Understanding PRSV diversity and evolution is crucial for formulating timely management strategies and breeding resistant cultivars. The molecular epidemiology of PRSV-P was investigated by analyzing the nucleotide sequences of the coat protein gene of different PRSV isolates worldwide, including the sequence data generated by collecting infected samples from South Florida. PRSV samples were collected from different papaya growing regions in Homestead and the wild papaya plantations surrounding Lake Okeechobee. Distinct PRSV clades were identified, corresponding to the U.S. and South American region, Southeast Asia (excluding India), and specifically India. The sequences obtained in the present study showed a close correlation with the aligned with the sequences from Cuba, Mexico, Jamaica, Guatemala, Venezuela, and previous sequences of the Florida isolates. The estimates of PRSV diversity showed an increase in the viral diversity, as the majority of the papaya growing regions are forming a separate clade. However, the evolution is slow, which could be due to the implementation of control strategies and the cultivation of resistant transgenic papayas.

Lack of winter chill accumulation is a major limiting factor for blackberry production in regions with mild or absent winters. For blackberry buds to release endodormancy they must be exposed to a range of temperatures between 0-7°C for a period of time that is genotype-specific. Insufficient chill in blackberries results in incomplete bud development, irregular budbreak, extended flowering periods, nonsynchronous fruit set, and lower fruit yields. The University of Arkansas Division of Agriculture (UADA) Fruit Research Station, located in Clarksville, Arkansas, experiences 1000 hours of annual chill each year, inhibiting the identification of low chill germplasm in the Arkansas Fruit Breeding Program. This study compares two methodologies for determining chilling requirements in six blackberry cultivars (Von, Natchez, Navaho, Ouachita, Sweet-Ark® Ponca, and A-2491T). Long-cane blackberry plants were exposed to controlled artificial chilling in a cooler, with removal at six weekly intervals from 0 to 840 hours, followed by exposure to forcing conditions in a heated greenhouse. Concurrently, field-grown plants of the same cultivars were exposed to naturally occurring chill hours in the field with six stem cuttings per genotype collected biweekly and forced under a mist bed in a heated greenhouse. The number of buds broken, reproductive laterals, and open flowers were recorded on a weekly basis for both methods. Results indicated that both methods effectively differentiated chilling requirements across cultivars, with budbreak and flowering progressing more rapidly and synchronously once plants reached their cultivar-specific chilling requirement. This study aims to identify an effective, repeatable method of evaluating blackberry chilling requirement in Arkansas to inform breeding decisions and identify low chill material in UADA blackberry germplasm.

Blueberry is the second major fruit crop in Alabama, followed by peach. However, blueberry production in Alabama is marginal compared to neighboring states such as Florida, Georgia, and North Carolina. Alabama growers still rely on old rabbiteye cultivars due to a lack of access to southern highbush blueberries (SHB) that are adaptable to the region. SHBs are valued for their early maturation and fruit quality but have not been widely adopted in Alabama due to their susceptibility to spring frost and other possible biotic or abiotic stresses. This project aims to introduce frost-tolerant SHB cultivars in Alabama through multi-environment cultivar evaluation. A total of 12 cultivars and 25 advanced selections of SHB have been evaluated in two locations in Alabama: the E.V. Smith Research Center (EV) in Central Alabama and the Brewton Agricultural Research Unit (BW) in South Alabama. Plants have been evaluated for 50% bloom, average berry weight (g), yield per plant (g), Brix (%), titratable acidity (TA%), and firmness (g/mm). Data from 2024 revealed that San Joaquin (5,035 g) and NC5289 (3,798 g) had the highest average yield at EV. At BW site, TH-2976 (3,375 g) and NC5289 (2,984 g) showed the highest yield. Colossus and Patrecia produced the largest average berry weight for both locations. In the BW, Colossus had an average berry weight of 4.72 g and Patrecia 3.8 g. At the EV location, both Colossus and Patrecia had an average of 3.0 g berry weight. For Brix, FL12-213A (14.7) and NC5326 (14.2) had the highest values at EV, while NC5326 (14.2) and Sentinel (13.8) had the highest values at the BW location. Overall, late-blooming selections such as NC5314 and NC5289 were identified as more suitable for Alabama to mitigate spring frost damage. The frost-tolerant cultivars identified through this project will significantly benefit small to mid-sized growers in Alabama by ensuring stable fruit production.

Macadamia is a commercially valuable nut crop, but the global industry is predominantly based on self-infertile cultivars. Pollinator scarcity can result in reduced nut set and lower yields. The development of self-fertile cultivars provides an opportunity to produce consistent yield in the absence of pollinisers and pollinators and may enhance orchard profitability. While previous studies identified varying degrees of self-fertility in macadamia, a comprehensive understanding of genetic diversity within a broad range of germplasm and the mechanisms of this trait remain unexplored. This study involved 11 commercial cultivars to identify genetic variation and mechanisms associated with self-fertility. An outcross pollen exclusion method was employed to assess self fertility. The percentage ratio of self- to open-pollinated nuts were calculated as a measure of self-fertility. To investigate the mechanisms underlying self-fertility, spatial separation of male and female reproductive organs as well as site of pollen tube growth inhibition have been examined. Pistil length, stamen length and stigma-anther distance were measured over two flowering seasons. Fluorescence microscopy was used to observe the pollen tube growth after self-pollinations. The self-fertility ranged between 17%-65% for six cultivars (‘HAES 741’, ‘HAES 791’, ‘A38’, ‘UQM40’, ‘K’, ‘Q’), which were identified as self-fertile. Five cultivars (‘HAES 344’, ‘A16’. ‘Daddow’, ‘D4’, ‘A268’) were identified as self-infertile. Pistil length of self-fertile cultivars ranged from 12.5 to 14 mm. Except for ‘A268’, which had significantly shorter pistils (8.5 mm), the pistil length of the self-infertile cultivars ranged from 11.5 mm to 14.5 mm. Stigma-anther distance was not associated with self-fertility. It was found that all cultivars exhibited similar stigma-anther distance, ranging from of 6 to 8 mm. There was non significant difference between the self-fertile and self-infertile groups for morphological floral traits. Pollen tube was inhibited in the upper third of style in self-incompatible pollinations. This inhibition indicated gametophytic self-incompatibility in macadamia. Further study will use a diverse collection of macadamia germplasm, including commercial cultivars, breeding lines and wild accessions to estimate heritability of self-fertility. Additionally, differential expressed genes in the pistils of self-fertile and self-infertile cultivars will be examined to understand the molecular mechanism regulating the trait. This research will assist in breeding of high-yielding, self-fertile cultivars for future plantations, ultimately supporting the sustainability of macadamia industry.

Black raspberry (Rubus occidentalis) and purple raspberry (R. idaeus x occidentalis) are fruits known for their pleasant and distinctive flavors. However, unlike their more popular cousin red raspberry (R. idaeus), little is known about what defines the characteristic aromas of black and purple raspberry. Using SPME-GCMS, the chemical compounds in the headspace of pureed black raspberry (4 genotypes), purple raspberry (5 genotypes), and red raspberry (2 genotypes) were collected and identified through a combination of gas chromatography and mass spectrometry. Chemical concentrations were calculated by integrating the area under the chromatogram curve, and calibrated with an internal standard of 2-octanol. By utilizing a random forest model, chemicals that were the most important for distinguishing fruit types (red vs. black vs. purple) were determined. Of the top 30 chemicals, 12 chemicals were described on Flavornet as detectable by a human nose in gas chromatography-olfactometry (GC-O), and the typical aroma described. Those 12 chemicals were then evaluated individually for significant differences across types (red, black, and purple raspberry). Among the chemicals that differed significantly across species were D-Carvone (caraway aroma), 1,3,8-p-Menthatriene (turpentine aroma); β-Ionone (violet, flower, raspberry, and seaweed aromas); α-Ionone (violet aroma); 2-Hexenol (leaf, green, wine, and fruit aromas); and α-Terpineol (oil, anise, and mint aromas). These results have implications for breeding new black and purple cultivars with the expected characteristic flavor. This instrumental approach also allows for tracking these aromas in breeding populations when utilizing interspecific hybridization to broaden the black raspberry germplasm in breeding.

The Vitis genus consists of two subgenera, Vitis and Muscadinia, which are both cultivated for wine, juice and fresh consumption. Fresh market breeding programs for grapes (V. vinifera) and muscadines (M. rotundifolia) aim to develop stenospermocarpic seedless and perfect-flowered cultivars. Despite chromosome differences and genetic divergence between the Vitis (2n=38) and Muscadinia (2=40) subgenera, stenospermocarpic seedlessness from V. vinifera was successfully introgressed into M. rotundifolia through conventional breeding. Currently, molecular markers for stenospermocarpy have not been developed or validated in Muscadinia and diverse Vitis accessions. Before the divergence of the Vitis and Muscadinia subgenera, two mutations occurred in perfect flowered ancestors, leading to male and female sterility and resulting dioecy in wild plants from both subgenera. Kompetitive Allele Specific PCR (KASP) markers have been recently developed targeting the known causal mutations resulting in male sterility (VviINP1) and stenospermocarpy (VviAGL11) in Vitis. The markers named, seedless_Arg197Leu_site56.fas and female_INP_indel_site56.fas, were evaluated for their diagnostic potential across Vitis and Muscadinia species through sequence alignments with published genomes. The predictive ability of these markers was assessed using a validation panel from the University of Arkansas Division of Agriculture Fruit Breeding program, which included 918 seedlings from Vitis x Muscadinia hybrid breeding populations. Additionally, a range of diverse Vitis and Muscadinia accessions with known phenotypes were included to enhance understanding of marker effectiveness, including cultivars, selections, and wild material from USDA germplasm repositories and public and private breeding programs. In total, 209 diverse accessions were assessed with the seedless marker, and 320 accessions were evaluated with the flower sex marker. The evaluation for seedlessness and flower sex took place over 2023 and 2024. Excluding incomplete phenotype and genotype data, the stenospermocarpic marker (seedless_Arg197Leu_site56.fas) accurately predicted seedlessness in 921 of 924 entries. Additionally, 148 out of 203 seedlings that did not produce fruit in both growing seasons were predicted to be stenospermocarpic. A t-test comparing vine caliper between seeded and seedless material (P =0.178) showed no difference in vigor between the seeded and seedless vine and suggested that the high number of seedless vines with no fruit may be caused by sterility factors linked to the introgressed Vitis stenospermocarpy locus. The flower sex marker (female_INP_indel_site56.fas) correctly predicted flower sex in 1,137 of 1,138 entries. Overall, the KASP markers showed outstanding predictive performance, achieving accuracy rates of 99.9% for flower sex and 99.7% for seedlessness across Vitis, Muscadinia, and hybrid germplasm.

'Ga. 6-1-269' is an hermaphroditic muscadine grape (Vitis rotundifolia) with bronze berries that was released by the University of Georgia (UGA) College of Agriculture and Environmental Sciences. Yields of ‘Ga. 6-1-269’ in Tifton, GA and Citra, FL trials were similar to other popular fresh-market muscadine cultivars. Berry size is very large (15-16 g) and similar to the cultivars 'Ga. 6-2-26' (Paulk®) and 'Supreme'. Fruit rot susceptibility of ‘Ga. 6-1-269’ was less than the bronze check cultivar 'Ga. 1-1-48' (Hall®) and similar to the black check cultivars 'Ga. 6-2-26' and 'Supreme'. Harvest time of ‘Ga. 6-1-269’ was about 5 days after 'Ga. 1-1-48' and about a week before 'Ga. 6-2-26' and 'Supreme'. ‘Ga. 6-1-269’ is recommended as an early-midseason fresh market bronze muscadine cultivar.

Florida Medallion™ ‘FL 16.30-128’ strawberry (Fragaria x ananassa; hereafter referred to as Medallion; U.S. Patent PP33,451) was released from the University of Florida in 2020. By 2024 this cultivar occupied approximately 15% of acreage in central Florida. The unique characteristics of this cultivar, in particular its early yields and fruity flavor, point to the breeding strategy employed in its development. Medallion originated from a 2016 cross between two unreleased selections. Marker-assisted selection was applied to this cross using a PCR-based marker for the FaFAD1 gene controlling production of gamma-decalactone, a volatile imparting fruity flavor. Seedlings homozygous for the functional allele were retained. At the advanced selection stage, trials of Medallion were conducted at the research plots of the University of Florida Gulf Coast Research and Education Center (GCREC) in Wimauma, FL and fruit were harvested for sensory and chemical analyses over five seasons. The increased dosage of the FaFAD1 gene resulted in high production of gamma-decalactone. Trained sensory panels perceived improved sweetness and strawberry flavor intensity of Medallion to be above the current industry standard ‘Florida Brilliance’. Additional background and data will be presented illustrating the early yield of this variety and other characteristics making it suitable for the central Florida industry and suggesting future breeding strategies for improving strawberry flavor.

Strawberries rank among the most economically significant horticultural crops in the United States, with a production value of approximately $3.4 billion in 2023. Year-round demand and widespread popularity necessitate extensive efforts to improve fruit quality, yield, and production in controlled environment agriculture (CEA). As part of these initiatives, optimizing runner production for the year-round availability of planting materials is crucial. The importance of photoperiod and light intensity in runner production has been highlighted previously; however, a thorough exploration of the relationship between the total light quantity received during the entire experimental period and runner production is lacking. This study assessed the responses of strawberry genotypes to sunlight and high-performance LED lighting in runner production. Continuous measurements of photosynthetic photon flux density (PPFD) and daily light integral (DLI) provided an accurate assessment of light exposure during the cultivation period across eight strawberry accessions. In a glasshouse under sunlight, plants experienced variable light conditions due to fluctuating weather, with an average DLI of approximately 10 mol m⁻² d⁻¹, whereas under LED lighting in a growth chamber, a stable DLI of 44.1 mol m⁻² d⁻¹ was recorded. No runner formation was observed under sunlight over 44 days, whereas minimal production in two accessions, PI 551445 and PI 616509, was observed within 12 days following the previous 44-day experimental period, with each accession producing one runner. In contrast, stable and high DLI led to significantly higher runner production. When an ANOVA test was conducted using only runner count data from the stable and high DLI conditions, significant differences in runner formation were observed among the tested strawberry accessions (F value = 2.91, p = 0.03). Accessions PI 616509 and PI 679822 produced the most runners, averaging 6.5 and 4.5, respectively, whereas PI 551692 and PI 551445 produced none and one runner, respectively. These results suggest that strawberry runner production depends on cumulative light exposure and genetic makeup. Overall, these findings provide valuable insights into optimizing strawberry runner production in CEA, demonstrating that stable, high-intensity LED lighting can effectively overcome the limitations of variable natural light and enhance year-round production efficiency.

Plant breeding is a lengthy and demanding research. Traditional strawberry breeding requires many man-hours to manually measure plant characteristics, record data, and evaluate various desired traits. Also, human biases and prior perceptions or expectations can play a role in skewing the results. Thus, the plant breeding program at the University of Florida has developed AI tools to assist in different stages of breeding research. Developed AI models have offered accurate and quick data analysis to identify and quantify plant phenome (anatomical characteristics and traits). This reduction in the number of manhours to manually measure, record data, and perform destructive sampling, has greatly increased the ability to screen more breeding lines with fewer resources (time, plants, and money). These AI models can accurately with a high level of consistency measure the size of plant canopy, flowers, runners, and fruit maturity repeatedly throughout the season to create an individual profile of each tested breeding line. Five YOLOv8 based (computer vision) models were trained for strawberry runner detection including GI, UL-AI, SL-AI, Hybrid I (GI SL-AI), and Hybrid II (GI SL-AI UL-AI). Hybrid II model achieved 91% precision accuracy and 83% mAP50 (mean average precision at IoU of 50%). The use of AI image and video analysis has been reducing the time and resources needed to develop new varieties.

Powdery mildew (PM) is a significant fungal disease in controlled environment horticulture (CEH). PM damages are increasingly being reported in fungicide-untreated and late planted open fields. Both field and protected systems in the major production regions of the world are facing heightened challenges due to the increasing disease occurrences. While PM has been efficiently managed by spraying chemical fungicides in field production, frequent use increases the risk of resistance development in pathogens. Additionally, fungicidal sprays may not be feasible to all CEH farms due to infrastructural restrictions or organic mode of production. The expansion of CEH production in Texas has created opportunities to extend strawberry cultivation from coastal regions to inland areas. However, PM management needs to be addressed given the conducive growing conditions in CEH. To study the prevalence of the disease, we evaluated 24 and 12 strawberry accessions arranged in a completely randomized design in two replications in the greenhouse and growth room conditions, respectively. In the absence of fungicide treatments, natural infections led to PM development within two weeks after transplanting. Disease ratings revealed incidence rates of 72% in the growth chamber and 49% in the greenhouse. The correlation between the two replications was 0.88 and 0.87, respectively. Accessions that exhibited little to no PM symptoms may be valuable for understanding host resistance mechanisms and could be utilized in breeding resistant cultivars in the future.

Fresh market tomato is one of the most valuable crops in the US. However, production relies heavily on manual labor, which can account for over 30% of the total per-acre cost, with a large portion attributed to harvesting. In the southeast US, most tomato plants are staked and tied, and fruit are hand-harvested multiple times as they mature, increasing labor costs and operational inefficiencies. Compact Growth Habit (CGH) tomato varieties have a shorter stature that does not need to be staked and allow for more labor-efficient harvesting options, providing a promising alternative to traditional production. A key breeding objective for CGH tomato is to develop lines with a more concentrated fruit set (CFS), defined as a higher proportion of fruits reaching maturity synchronously. This trait would enable once-over harvesting, substantially reducing labor inputs while improving operational efficiency. Furthermore, the successful implementation of once-over harvest strategies in CGH tomatoes may facilitate the adoption of mechanized harvesting systems, addressing labor shortages and enhancing scalability in fresh market tomato production. This study aims to develop a computer vision model to automate detecting and quantifying tomato fruits and flowers in CGH breeding trials. High-resolution RGB images of top-view canopies were collected from experimental plots during the spring and fall seasons of 2024, capturing phenotypic variability across diverse environmental conditions and growth stages. The dataset is undergoing preprocessing, annotation, and augmentation to enhance model robustness. A YOLO-based object detection model will be trained to classify and quantify flowers and fruits. Model performance will be assessed using standard evaluation metrics, including precision, recall, and F1-score. By accurately detecting and quantifying fruits and flowers across developmental stages, this system will enable breeders to analyze flowering progression and identify CGH tomato lines with improved CFS, supporting the selection of varieties optimized for once-over harvesting. Preliminary model training using 1,370 training images, 116 validation images, and 335 test images in roboflow using YOLOv11 yielded promising results, with a mAP@50 of 94.7%, precision of 85.1%, and recall of 91.0%, demonstrating the model's potential to support phenotyping for concentrated fruit set. Future research will focus on enhancing detection accuracy, expanding dataset diversity, and integrating multispectral imaging techniques to optimize model performance and applicability across different environments.

Papaya ringspot disease caused by papaya ringspot virus P (PRSV-P), is restricting the commercial cultivation of papaya worldwide. Several measures have been taken to control the disease, including the application of aphicides, identifying host plant resistance, and transgenics. However, only genetically engineered papayas carrying the viral coat protein have been found to effectively control the disease. Transgenic papayas are not cultivated worldwide due to ethical regulations. Assessing the diverse papaya germplasm for resistance to PRSV could be a suitable alternative. Therefore, the present study was undertaken to assess PRSV resistance in 96 accessions, including 36 commercial accessions and 57 wild accessions. To identify novel resistant sources, the accessions were mechanically inoculated with PRSV under controlled conditions. The inoculated plants were continuously monitored for the appearance of PRSV-like symptoms and scored for disease severity, ranging from 0-5. Among all the accessions tested, only two accessions, HCAR 46 (Vasconcellea pubescens) and HCAR 177 (V. stipulate), did not show any symptoms. To further assure that no virus is present in these plants, an RT-qPCR was performed with PRSV coat protein-specific primers. The accession HCAR 46 showed the presence of a faint amplicon of 950 bp. However, no PSRV-specific amplicon was observed in HCAR 177. To further confirm the presence of PRSV, the amplified products were sequenced and showed over 95% sequence similarity with PRSV. The PRSV-resistant genotype identified in the present study could be used to breed PRSV-resistant cultivars.

Verifying Parentage of Offspring from Crosses of the Pawpaw (Asimina triloba) Cultivar ‘Sunflower’ and the Cultivars ‘Susquehanna’ and ‘KSU-Chappell’ using Simple Sequence Repeat (SSR) Markers Nabin K. Adhikari, Dr. Kirk W. Pomper, Jeremy Lowe, Dr. Srijana Thapa Magar, and Sheri Crabtree College of Agriculture, Health and Natural Resources, Kentucky State University Pawpaw (Asimina triloba), a North American tree fruit in the early stages of commercialization, is typically found in clonal patches in forest understories. Cultivated pawpaws exhibit superior size, flavor, and appearance compared to their wild counterparts. Pawpaw is generally considered self-incompatible due to its protogynous flowers, though anecdotal evidence suggests self-compatibility in the ‘Sunflower’ variety. Previous research at Kentucky State University used simple sequence repeat (SSR) markers, a class of co-dominant genetic markers that target hypervariable regions of the genome, to confirm that ‘Sunflower’ is capable of self-pollination. However, there is little information on optimal pollinizer relationships and which cultivars serve to promote fruit set in cross-pollinations. This study aims to verify the parentage of offspring from crosses between ‘Sunflower’ and the cultivars ‘Susquehanna’ and ‘KSU-Chappell’, as well as the advanced selection 7-90 using simple sequence repeat markers. Leaves of parent trees and offspring were collected for DNA extraction. Young leaves were collected and were frozen (-15 ºC) until DNA extraction. DNA extraction was carried out using a DNAMITE Plant Kit (Microzone Ltd. Haywards Heath, West Sussex, UK). PCR was performed using SSR markers developed by Pomper et al., 2010. PCR products will be separated using a SeqStudio (Applied Biosystems, Foster City, CA) capillary electrophoresis system, and genotyping will be performed with GeneMapper software (Applied Biosystems, Foster City, CA). Parentage verification will be determined by looking for the presence or absence of alleles from the purported parents in the offspring. Offspring were categorized as self-pollinated if only alleles from the pollen recipient parent were present in the offspring, expected cross-pollinated if alleles from both parents were present, or unexpected if unknown alleles were detected.

The need to improve crops has never been critical with the rising population and climate change resulting in high abiotic stress and disease pressures in production areas. In recent years, artificial intelligence (AI)-based approaches have been implemented in the context of plant breeding and crop improvement. Modern AI tools hold the promise of accelerating the development of resilient, higher-yielding, and more sustainable horticultural crops, by rendering a deeper understanding of complex genetic systems and phenotypes, and how these interact with their environment to express desirable traits. As an approach, AI is an important component of the plant breeding toolbox which may now currently be an indispensable addition to modern vegetable breeding programs. For example, AI allows for the prediction of phenotypic values through genetic markers, and this allows plant breeders to perform selection even before the trials are conducted in the field. The ASHS Vegetable Breeding and Interest Group seeks to provide research updates from experts who have worked on the applications of AI in crop breeding and genetic improvement. The workshop will provide a summary of various AI methodologies, recent advances, and render opportunities for future collaboration and research directions in the implementation of AI in vegetable breeding programs. Objectives 1. Summarize the different AI approaches used in breeding and genetic improvement of various traits in vegetables 2. Provide the attendees with recent advances in AI for plant breeding 3. Discuss future research directions and applications of AI in plant breeding programs The workshop will be conducted during the annual ASHS meeting (July 28- August 1, 2025) in New Orleans, Louisiana. The workshop will be in-person. Audience: The workshop will be open to all ASHS attendees (both public and private sectors) and will be interactive.

Moderators: Dennis Lozada, New Mexico State University
Devi Kandel, Langston University

Speakers:

• Cheryl Dalid, University of Florida - Leveraging Phenomics and Genomics Data in Strawberry Breeding
• Stephen Ficklin, Washington State University - Towards Identification of Biomarkers for Environmentally-controlled Traits
• Madhi Haghshenas-Jaryani, New Mexico State University - AI-enabled Agricultural Robots and Intelligent Machines for Precision Farming of Chile Pepper Cultivation in New Mexico
• Tanzeel Rehman, Auburn University - AI-Driven High-Throughput Phenotyping for Assessing Physiological Stress in Blueberry
• Kevin Wang, University of Florida - AI-Powered Phenomics: Accelerating Breeding Across Horticultural Crops
  

A forum for discussion of potential collaborations with regards to fruit, vegetable, and edible crops – i.e. citrus, breeding, production systems, postharvest, pomology, crop management, viticulture, etc.

Blueberry is a high value fruit crop and there is an increased demand for its cultivation and consumption all over the world. The blueberries are grown in diverse regions with varied weather, soil, biotic and abiotic stress limiting their yield. Interspecific hybridization plays a significant role in broadening the genetic base of blueberries that subsequently helps in developing improved cultivars adapted to specific regions. The genetic diversity for cultivated rabbiteye (RE) (2n=6x=72) blueberries is very narrow. Introgression from wild and other cultivated species would provide beneficial diversity for RE blueberries. Vaccinium elliottii (2n=2x=24) is an early flowering, tall and highly deciduous wild blueberry with small black fruits. Like RE, it is adapted to a wide range of soil types in the southeastern United States. On the other hand, southern highbush is a cultivated tetraploid (2n=4x=48) with high fruit quality but requires intensive soil amendment. To broaden the genetic base of blueberry breeding, interspecific crosses were made between three southern highbush breeding lines and V. elliottii. The success of these crosses was challenging due to strong triploid block from heteroploid crosses. Out of 422 pollination events only 8 triploid seedlings were produced, and their ploidy level was confirmed by flowcytometric analysis. Three seedlings were confirmed to be triploids (3x) however, it is expected that triploids are sterile. Seedlings of the triploids were established in tissue culture and chromosome doubling of these triploid hybrids was carried out to improve their crossing efficiency with cultivated blueberries. The shoots produced through tissue culture were treated with 0.02% colchicine for 48 hours and transferred to woody plant medium (WPM). Synthetic hexaploid hybrids produced from this study will be cross compatible with RE blueberries. These synthetic hexaploid hybrids will bridge the ploidy gap among diploid, tetraploid and hexaploid blueberry species.

Grapevine cold hardiness is a critical trait that determines the geographical distribution and winter survival of cultivars, thus a key consideration for viticulture in regions with severe winter conditions. This study investigated the cold hardiness of 312 Vitis riparia F1 hybrids, using differential thermal analysis (DTA) and survival assessments at 4°C over seven and 28 days. The DTA analyses to identify significant changes in progeny lethal temperature exotherm (LTE) values with a wide range of LTE values from -24.3°C to -12.3°C observed after 28 days of cold acclimation. The mean LTE value improved from -16.8°C after seven days to -18.6°C after 28 days with 80.2% of progenies showing significant decreases in LTE values. Progenies were divided into five groups based on cold hardiness: very cold hardy, cold hardy, moderately hardy, susceptible, and very susceptible. Principal component analysis (PCA) demonstrated clear separation among the five cold hardiness groups, with PC1 accounting for 71% of the variance. This study provides valuable insights into the genetic basis of cold hardiness in V. riparia progenies, offering critical information for grape breeding programs aimed at developing cold-resistant cultivars. The identification of highly cold-hardy progenies and the understanding of their genetic diversity will aid in selecting parent plants for breeding, ultimately improving grape production in cold regions.

Combining muscadine (M. rotundifolia) with bunch grapes (V. vinifera) addresses the challenges faced by each species. Muscadines provide strong disease resistance and adaptability to the southeastern U.S climate but lack key fruit quality traits such as seedlessness and crisp texture. In contrast, V. vinifera, produces high-quality fruit but is highly susceptible to diseases like Pierce’s disease and powdery mildew. Hybridization between the two aims to retain the desirable fruit characteristics of V. vinifera while incorporating the resilience of muscadines. Understanding the genetic basis of key agronomic traits in Vitis × Muscadinia (V × M) hybrids is essential for introgressing valuable traits such as seedlessness, disease resistance, and flavor into breeding populations. This study aimed to develop a high-density genetic linkage map to investigate the inheritance of seedlessness, sterility, and recombination patterns in wide hybrids. The mapping population was derived from a cross between AM-116, a seeded Muscadinia rotundifolia selection, and JB15-43-N0-25, a seedless V × M hybrid. Phenotypic evaluations of traits such as flower sex, winter injury, berry size, berry, color, yield, seedlessness, cluster architecture, and vigor were collected and integrated with genotypic data to create a linkage map and identify quantitative trait loci for these traits. RhAmpSeq genotyping was initially used as the primary method to genotype the population and assess recombination frequency across homeologous and homologous chromosome regions. However, because rhAmpSeq markers were designed using Vitis genomes without incorporating Muscadinia, marker coverage in Muscadinia genomic regions was limited. To overcome this limitation, SkimSeq whole-genome sequencing was later employed to construct a high-density linkage map. Principal Component Analysis (PCA) of genomic data revealed that individuals positioned closer to the V × M parent (JB15-43-N0-25) had a higher proportion of Vitis ancestry and an increased number of homeologous chromosomes. This pattern suggests that structural genomic incompatibilities affecting segregation distortion and recombination rates may result in reduced recombination in homeologous regions in V × M hybrids. These findings provide new insights into the genetic mechanisms governing sterility, recombination, and trait introgression in Vitis × Muscadinia hybrids, contributing to the development of breeding strategies aimed at integrating desirable traits across subgenera. Understanding these factors is crucial for overcoming genetic barriers in interspecific breeding and optimizing hybrid vigor for commercial muscadine grape production.

Eastern filbert blight (EFB) disease caused by the fungal pathogen Anisogramma anomala (Peck) E. Müller is a major threat to Oregon’s hazelnut (Corylus avellana) industry. Although cultivars with ‘Gasaway’ resistance have sustained the Oregon hazelnut industry, ‘Jefferson’ and ‘McDonald’ trees protected by a dominant allele for resistance from ‘Gasaway’ have shown small cankers when under high disease pressure for several years. In late 2023, a few orchards in the northern Willamette Valley reported infections on ‘Gasaway’ protected trees with highly aggressive cankers and fully developed stromata, indicating the ability to reproduce on resistant varieties and signaling the breakdown of ‘Gasaway’ resistance in Oregon. The OSU hazelnut breeding program has conducted extensive EFB screening efforts on curated germplasm, and more than 30 sources of EFB resistance have been assigned to a linkage group (LG) using SSR loci and disease score correlation analyses. Fine mapping of the LG7 resistance region using the ‘Ratoli’ and OSU 1166.123 backgrounds with simple sequence repeat (SSR) and PCR allele competitive extension (PACE) SNP genotyping assays narrowed the resistance region. However, gene expression profiling is desired to further elucidate which candidate genes overlap between fine-mapping efforts and gene expression to refine marker development efforts for LG7 resistance. The objective of this study was to identify differentially expressed genes (DEGs) in six hazelnut genotypes (‘Ennis’, OSU 1026.073, OSU 1166.123, OSU 541.147, ‘Ratoli’, and ‘Sacajawea’) at different stages of EFB infection. Layered and grafted trees with ‘McDonald’ rootstocks were grown in 3L pots at the OSU West Greenhouses in Corvallis, OR in spring 2023. Inoculations were conducted in an outdoor container pad and new shoot tips with at least two true leaves were spray inoculated with a spore suspension (1x106 spores·mL-1) until run-off. Apical shoots (2-3 internodes) from four biological replicates were collected at 0, 12, 24, 48, 72, 96, 168, and 240 hours post-inoculation, with the addition of two biological mocks sprayed with deionized water. Total RNA was extracted and sequenced using a BRB-seq library prep for the Illumina NovaSeq X Plus platform. Detailed analyses of differentially expressed genes between susceptible and resistant genotypes during the initial stages of EFB infection will be discussed. The results of this study will provide valuable insights into the molecular resistance of hazelnut to EFB, aid marker development for breeding EFB-resistant cultivars, and facilitate the pyramiding of R-genes in a single clonal selection for more durable resistance.

Peach fungal gummosis (PFG), caused by fungal pathogens in the Botryosphaeriaceae family, including Botryosphaeria dothidea, Lasiodiplodia theobromae, and Diplodia seriata. This disease is a major threat to Prunus production worldwide. The initial symptoms often remain latent until trees are exposed to stress, at which point it can lead to substantial yield losses and even tree mortality. Given the lack of curative fungicide options and the difficulty of managing prolonged latent infections, genetic resistance has become a central focus for integrated PFG management strategies. A key breakthrough in this effort was the identification of Botd8, a major resistance locus derived from the almond cultivar ‘Tardy Nonpareil.’ Mapped to linkage group 8, Botd8 confers dominant resistance to B. dothidea and co-segregates with the red leaf locus (Gr). Its resistance effect was validated in multiple environments and under different inoculation methods, including field, trellis, and wound inoculation. Further validation using detached stem and leaf assays confirmed that genotypes homozygous or heterozygous carrying Botd8 exhibited significantly reduced lesion development following inoculations with B. dothidea and D. seriata. However, Botd8 was not effective against L. theobromae, underscoring the need for additional resistance sources. The strong correlation between detached stem assay results and field ratings also demonstrated the utility of these rapid, non-destructive screening tools in breeding programs. To expand resistance options beyond almond-derived sources, a recent study focused on the low-chill peach landrace ‘Okinawa’. A segregating F1 population from ‘Okinawa’ × (‘Flordaguard’ × PI91459) was phenotyped for disease severity and genotyped via Genotyping-by-Sequencing. QTL analysis revealed a novel resistance locus on linkage group 6, distinct from Botd8. This QTL consistently explained 29–41% of the phenotypic variation across two years, suggesting a polygenic basis for resistance in peach. Notably, the Botd8 haplotype was common in high-chill cultivars but absent in low-chill germplasm, positioning ‘Okinawa’ as a valuable resistance source for subtropical breeding efforts. Collectively, these studies establish a comprehensive framework for developing PFG-resistant peach cultivars

As a native species in the southeastern U.S., rabbiteye blueberry (Vaccinium virgatum Aiton) is known for its resilience to environmental stresses and adaptability to various soil types. Rabbiteye was the dominant species grown in the southern U.S. before the rise of southern highbush blueberries (V. corymbosum L. interspecific hybrids). Compared to southern highbush, rabbiteye cultivars are often perceived as seedy and have thick skin. Limited genetic diversity, compounded by repeated use of elite parents and decreased breeding efforts, poses challenges for rabbiteye improvement. To facilitate more efficient rabbiteye breeding in the future, this study aims to assess the genetic diversity of rabbiteye cultivars through pedigree analysis and evaluate the impact of interspecific hybridization on modern cultivars. The pedigree data of 180 rabbiteye blueberry accessions were analyzed to calculate inbreeding coefficients, coefficients of coancestry and the genetic contribution of founders. Five founders ‘Myers’, ‘Black Giant’, ‘Ethel’, ‘Clara’, and ‘W4’, collectively account for a minimum of 73% of the genetic composition of rabbiteye cultivars. The level of interspecific hybridization has been limited in rabbiteye breeding, with V. corymbosum contributing 3% of the genetic composition of rabbiteye cultivars and 1% from other species such as V. constablaei and V. darrowii. The narrow genetic base and repeated use of common parents led to an increase in inbreeding coefficients, from an average of less than 0.0002 before 1980 to 0.014 in the 2000s. In the future, it would be valuable to increase the use of exotic materials from other species or within the rabbiteye germplasm to broaden the genetic base while introducing valuable alleles. Further evaluation of population structure with genomic information is needed to validate pedigree information and provide a more accurate assessment of the genetic diversity and population structure.

The development of Vitis × Muscadinia (V x M) wide hybrids, combining the disease resistance of muscadines (M. rotundifolia) with the berry quality attributes of V. vinifera grapes has be en a longstanding ambition of breeders. Stenospermocarpic seedless muscadine hybrids and wine grapes carrying powdery and downy mildew resistance introgressed from muscadines have been developed using classical techniques without the assistance of molecular tools through sustained effort over a century. However, progress has been impeded by differences in chromosome number (Vitis=38 chromosomes and Muscadinia=40 chromosomes) and genetic distance between the subgenera. A major objective of the new Vitis x Muscadinia Specialty Crop Research Initiative project is to develop and deploy new genotyping platforms and chromosome painting visualization tools to help grape and muscadine breeders track introgressed chromosomal regions in wide hybrids and accelerate trait discovery and cultivar development in new V x M hybrids. In order to develop a chromosome-painting visualization tool for V x M hybrids, we first conducted a large-scale population diversity analysis using historical data from the rhAmpSeq Vitis core panel. Structure analysis was performed to identify individuals belonging to Muscadinia and five additional subpopulations within subgenus Vitis. Approximately 33,000 marker haplotypes were identified as unique to Muscadinia and 671,000 haplotypes were identified as present only in Vitis. This haplotype information was used to create automated chromosome painting visualizations of introgressed segments in historical and modern V x M hybrids. These visualizations allow us to identify which Vitis-type hybrids carry muscadine introgressions in known resistance loci on chromosomes 12 (Run1/Rpv1), 18 (Run2/Rpv2), and 14 (Ren5) and which Muscadinia-type hybrids have introgressions associated with stenospermocarpy and other fruit-quality alleles from Vitis. This information will assist grape and muscadine breeders in planning crosses and discovering new disease resistance and fruit quality alleles. In the coming months, we intend to extend this strategy to a new low-cost DArTag genotyping panel that has been designed to amplify polymorphic markers in both subgenera. Breeders will then be able to rapidly assess which chromosomal regions and major-effect fruit quality and disease resistance alleles are present in a homozygous or heterozygous state in all new V × M hybrids.

Citrus leaves exhibit remarkable morphological diversity, yet the genetic underpinnings of this variation remain poorly understood. In this study, we investigated the genetic architecture controlling citrus leaf shape by performing genome-wide association studies (GWAS) on over 3,000 digitized leaves collected from 150 citrus varieties across two years (2021 and 2022). Using a 50K SNP Axiom array, we identified consistent genomic regions on chromosomes 2, 3, 5, and 7 that were significantly associated with leaf length, width, and area. Linkage disequilibrium patterns within these regions revealed variability, and gene ontology enrichment indicated that genes involved in cell division, photosynthesis, and transcriptional regulation are overrepresented. Our results highlight the strong and heritable basis of leaf morphology in citrus and suggest that regulatory mechanisms play a major role in shaping these traits. This work provides key insights into the genetic control of leaf form and has potential implications for citrus breeding and functional genomics.