ASHS 2025 Conference

Powdery mildew, caused by the fungus Erysiphe pulchra, is one of the most serious diseases affecting the popular ornamental tree flowering dogwood (Cornus florida). Employing gene editing techniques such as CRISPR to introduce powdery mildew resistance by inactivating the Mildew Locus O (MLO) gene requires an efficient genetic transformation system. This novel research will fill a critical gap in our knowledge of flowering dogwood biotechnology. Previous research efforts have genetically transformed embryogenic dogwood cultures, now we are aiming to produce transgenic plantlets. Recent research focused on using the RITA® temporary immersion bioreactor system for testing germination of somatic embryos and conversion to plants. The primary test was the impact of the plant growth regulator (PGR) gibberellic acid (GA3). For this experiment, we analyzed the impact of different environmental light exposures on dogwood embryo stress levels by observing anthocyanin production. The starting material was unwashed callus transformed with the GUS reporter gene and subjected to one of three RITA® treatments to examine the influence of varying light levels. Treatments included full darkness, continuous low light, and a combination of both light conditions for different durations of time. Few somatic embryos germinated from the treatment with 60 days of full darkness, but the anthocyanin stress was absent. We observed the same result for constant low light exposure except for exponential growth of the transgenic callus. The treatment in which the somatic embryos were in full darkness for 30 days and switched to low light for another 30 days showed a higher germination rate, but there were increased signs of anthocyanin stress. Implementation of this research will assist in the optimization of the production of plantlets from dogwood cultures transformed with a CRISPR-Cas9 construct that can inactivate the MLO gene to obtain powdery mildew resistance.

Fresh fruits and vegetables are invaluable for human health, but their quality deteriorates before reaching consumers during distribution due to ongoing biochemical processes and compositional changes. The current lack of any objective indices for defining “freshness” of fruits or vegetables limits our capacity to control product quality and leads to food loss and waste. In this work, we undertook interdisciplinary research to address plant science challenges related to food security and human health. This work has leveraged machine learning technologies and multi-omics tools to understand post-harvest senescence and microbial spoilage of fresh produce for the purpose of developing a simple imaging “FreshID” device to evaluate fruit and vegetable quality. In essence, we are proposing a comprehensive research program to identify proteins and compounds as “freshness-indicators” and to aid development of an innovative and easy-to-use accessibility tool to accurately estimate the freshness and/or contamination of produce. The goal of the proposed research will be advances in both basic research and applied science. Such a tool would allow a new level of post-harvest logistics, supporting availability of high-quality, nutritious, fresh produce.

Plant natural promoters are always very long and contain many different promoter motifs, providing complex expression patterns, while synthetic promoters can be constructed to be very short in sequence and very strong in promoter strength. Bioinformatics-assisted de novo promoter motif discovery searches for statistically overrepresented motifs without the inclusion of biological information, leading to limited prediction efficiency. To overcome this limitation, we have developed a novel ensemble approach by mapping the motifs detected by a set of selected bioinformatics tools back to the promoter sequences and looking for overlapping motif regions among the detected motifs. Using this approach, we searched and identified novel constitutive promoter motifs from the soybean genome. Seven user-friendly bioinformatics tools, including BioProspector, CisGenome, HOMER, MEME, MotifSuite, RSAT Plants, and Weeder were employed for the de novo discovery of constitutive motifs among 11 published soybean constitutive promoters. A total of 62 promoter motifs were detected among the 11 soybean constitutive promoters by at least four of the seven bioinformatics tools. A tetramer (4×) of each promoter motif was cloned in front of the minimal 35S promoter driving GUS reporter gene expression, and used for tobacco leaf agroinfiltration and stable Arabidopsis transformation. Quantitative GUS activity assays following transient tobacco leaf agroinfiltration identified 26 of the 62 promoter motifs that drove GUS expression significantly higher than the basal level conferred by the minimal 35S promoter. Histochemical GUS analysis of stable transgenic Arabidopsis seedlings found that 16 of the 26 promoter motifs were 19 ~ 60 bp in length and exhibited constitutive expression with variable promoter strength, and 7 of the 26 promoter motifs showed strong constitutive expression which was comparable to (slightly weaker than) the 35S promoter. Thus, these novel constitutive motifs can be used to drive constitutive gene expression in dicot species.

In sweetpotato (Ipomoea batatas L.), the sink strength of developing adventitious roots limits storage root formation. Sucrose synthase (SuSy) has been identified as a marker for sink strength in developing storage roots. In model systems, declining nitrogen (N) availability has been associated with increased carbohydrate allocation to root systems. To test the hypothesis that N limitation triggers increased SuSy activity that leads to storage root formation, we subjected sweetpotato cv. ‘Beauregard’ to progressively declining N treatments in a split-root system. SuSy expression and root system architecture were evaluated over 15 days, and storage root formation was assessed at 50 days. Declining N availability enhanced SuSy activity in the root base tissue across all time points and was associated with increased lateral root count at 15 days. Previous work has shown that the anatomical cue of the onset of storage root formation, the appearance of anomalous cambia, is initially limited to the root base tissue. The omission of N was associated with decreased root base SuSy activity and an overall reduction in root architectural attributes. These data support the hypothesis that declining N could be a critical switch for storage root formation in sweetpotato. Our findings have profound implications for increasing N fertilizer efficiency and enhancing our understanding of the intrinsic and environmental variables that mediate storage root formation and productivity in this globally important crop.

This talk presents an integrated approach combining metabolomics and proteomics to advance plant research. By connecting metabolic profiles with protein expression and function, we can gain deeper insights into plant function, stress responses, and development, with implications for crop improvement and sustainability. The presentation will highlight recent methodological advances, case studies, and the potential of multi-omics approaches to drive innovation in plant science research.

As a member of Convolvulaceae family, sweetpotato (Ipomoea batatas L.) is an important crop for food security. As one of the top three vegetable crops grown in Mississippi, one major limitation to sweetpotato production is the cumulative effect of virus infection leading to cultivar decline and yield losses. To produce virus-tested sweetpotato seedlings, we developed meristem-tip culture technology combined with heat treatment to provide farmers with healthy propagating materials that are free of detectable viruses. In this study, totally 30 lines of sweetpotato have been collected in Mississippi and beyond. The plants were first examined with the infection of five of the most prevalent viruses by using nucleic acid-based polymerase chain reaction (PCR) and reverse-transcription PCR (RT-PCR) techniques, which showed high sensitivity and confirmation at the genomic level of viral species and strains. Primers targeting to conserved regions of the know sweetpotato viruses were used for this nucleic acid based detection. The effective protocols for sweetpotato viral detection and viral removal were well developed in this study. The optimized protocols have been used for the purpose of viral detection and eradicating from elite sweetpotato lines in Mississippi. Virus-free planting material has been propagated in Agriculture Research Station of Alcorn State University for performance evaluation.

Bigleaf hydrangea, Hydrangea macrophylla, is a popular ornamental shrub beloved worldwide for its large colorful inflorescences. As of 2019, bigleaf hydrangea topped $155 million in total sales in the United States. However, diseases impact the health, appearance and ultimately the salability of bigleaf hydrangea. One such disease is powdery mildew, caused by the fungus Golovinomyces orontii. Powdery mildew is a biotrophic obligate, which means that it will only grow on a living host, making it particularly hard to investigate. Inoculating plants via tapping infected leaves against clean leaves is the most common inoculation method; however, this method results in an unknown amount of inoculum and inconsistent infection. Quantifiable and consistent methods are needed to accurately and reproducibly study powdery mildew disease of bigleaf hydrangea. The purpose of this experiment was to compare two inoculation methods, an inoculation box and spray inoculation method, for inducing powdery mildew disease in bigleaf hydrangea. For the box inoculation, 6 infected leaves per plant were tapped above a 48-micron mesh and gently dusted through to land on the plant surface. A still air chamber was designed to be set over the box so that powdery mildew does not get disturbed by air currents. For the spray inoculation, 6 infected leaves per plant were combined into a spray by rinsing the leaves with deionized water, adding Tween 20 to aid with even dispersion and applied to the plant using a spray bottle. Powdery mildew was then evaluated on a scale of 0-100% and the area under disease progress curve (AUDPC) was calculated. The final disease severity of hydrangea inoculated via the box and spray method after 4 weeks of observation were 10.0 and 20.0%, respectively. These results will provide valuable information on more consistent inoculation methods using powdery mildew.

Blueberry (Vaccinium spp.) is one of the most economically important woody plant species because its fruit is rich in antioxidants such as anthocyanin, which offer beneficial effects on human health. Thus, the demand for blueberry production and for the development of novel elite cultivars has been continuously increasing. Although new blueberry cultivars have been developed by cross breeding for more than a century, the conventional breeding approaches are time-consuming and labor-intensive due to the associated characteristics that hinder efficient breeding such as long juvenile phase, polyploidy, and heterozygosity. Genetic engineering offers a promising approach to confer a desirable trait to elite cultivars. In particular, the recently developed genome editing technology enables precise modifications of plant genomes. We aim to apply genome editing to improve agronomically important traits in blueberry, specifically anthocyanin and sugar content. Towards the development of high anthocyanin blueberry, we targeted an anthocyanin repressor gene, VcMYBC2. So far, we successfully obtained 3 lines with all-alleles of VcMYBC2 were mutated. An increase in anthocyanin content in fruit is expected in the mybc2 mutants. Regarding sugar content, we targeted invertase inhibitor (INVINH) gene that is involved in sugar metabolism. Invertase promotes sucrose unloading in the fruit by maintaining a gradient of sucrose concentration between source leaves and fruits, while INVINH represses this process. Thus, higher sugar accumulation is expected in invinh mutants. Three transgenic lines harboring CRISPR-Cas9 vectors targeting VcINVINH genes that are highly expressed in fruit tissue, were obtained. The mutated allele frequencies of the mutants ranged from 21-67%. Additionally, we generated transgenic blueberries overexpressing FLOWERING LOCUS T (FT), a mobile florigen signal gene that induces flowering. A previous study demonstrated that blueberry scions grafted to FT-overexpressing lines could show early flowering. We thus assume that the mybc2 and invinh mutants may flower earlier when they are grafted onto the FT overexpressing rootstock, which will accelerate our fruit phenotype evaluations. The FT-overexpressing rootstock may also be utilized to facilitate the production of null-segregant mutants.

Agrobacterium-mediated transformation is widely used in plant genetic engineering. This method involves both Agrobacterium infection and plant regeneration. In this context, establishing an efficient plant regeneration system is a critical prerequisite for genetic engineering in plants. This study aims to identify highbush blueberry (Vaccinium corymbosum L.) cultivars suitable for genetic transformation. Furthermore, we seek to elucidate the molecular and genetic factors that determine genotype-dependent shoot regeneration capacity by utilizing the diverse genetic background in highbush blueberries. Additionally, this study explores cultivar-specific differences in Agrobacterium susceptibility, which remain unexplored in highbush blueberries. Regeneration from leaf explants of 15 highbush blueberry cultivars was investigated on media containing 1.0 mg/L TDZ or 1.0 mg/L TDZ and 0.5 mg/L NAA. There was considerable variation in callus formation and regeneration rates, the number of regenerated shoots, the time required for regeneration, indicating that regeneration in highbush blueberry is highly genotype-dependent. The regeneration rate was high (>75%) in ‘Blue Muffin’, ‘Legacy’, ‘Gulfcoast’ and ‘Georgiagem’. However, ‘Georgiagem’ required three additional weeks for shoot regeneration from the time of meristem formation compared to the other three high regeneration cultivars. All four northern highbush cultivars exhibited low regeneration rates (

Protein phosphatases, particularly PP2C families, are vital regulators of cellular activity through the removal of phosphate groups from proteins. Numerous biological processes, such as hormone signaling, reactions to heat and drought stress, and abiotic stress tolerance, are impacted by this dephosphorylation process. This study presents comprehensive genomic analysis, evolutionary assessment and transcript profiling of the PP2C gene family in sweet potato, a crop of major agricultural and nutritional importance. A total of 74 PP2C genes have been identified in sweet potato. Among them, 7 gene pairs were identified as segmental duplication while 5 pairs as tandem duplications. Phylogenetic analysis grouped them into distinct clusters, indicating potential functional divergence. Gene structure analysis provided insights into the arrangement of coding and non-coding regions. Motif and domain analysis highlighted conserved protein sequences aiding functional predictions. Synteny analysis compared genomic regions across species identifying homologous genes and tracing genome evolution. The study of cis-regulatory elements in promoters helped map gene regulations. Gene expression analysis is currently being conducted to determine the transcript levels of PP2C during salinity and drought stress. The results provide a basis for additional validation of the roles of the PP2C gene in sweet potatoes and advance our knowledge of the evolutionary background and functional significance of PP2C in biotic and abiotic stress response.

The origin of the cultivated strawberry traces to the 1700s, when representatives of the octoploids F. chiloensis and F. virginiana – previously brought to Europe from South and North America, respectively – were grown in proximity in European horticultural gardens. Cross-pollination produced hybrids that were quickly recognized for their unique and desirable combinations of morphological and fruit characteristics and were brought into cultivation and breeding (Hancock 1999). Traditional breeding objectives are the following (Rosati 1993): a production of relatively large berry size in order to limit the cost of harvest, a firmer fruit with regular shape and long shelf life, which is easy to harvest, an increase in the total yield, an improvement in fruit appearance (color, shape, brightness), and disease resistances. The recent origin makes F. ananassa one of the youngest of contemporary crop species. Bottle neck existing in strawberry traditional breeding is that it is difficult to manipulate single genes to control strawberry characteristics, modern genetic transformation and genome editing technology provide promising ways for single gene control in strawberry. Diploid strawberry transformation has been reported, limited report was available for transformation of octoploid cultivated strawberry. We report an efficient Agrobacterium mediated strawberry transformation system with the aid of GFP visual selection. First three open leaves from 4 weeks old in vitro plants were harvested, and leaflets were separated from each other and inoculated with Agrobacterium tumefaciens GAV3101 contains a binary vector with GFP and hygromycin resistance genes. Transgenic callus and shoots obtained with GFP visual selection with high efficiency. PCR double check proved transgenes in transgenic plants. Transgenic plants are phenotyping in the greenhouse.

Flowering plays a crucial role in blueberry production since fruits develop from flowers. In plants, FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1), which interact with the bZIP transcription factor FD, are central regulators of flowering. This study investigates the roles of their homologs in blueberries, VcTFL1 and VcFD, using RNA interference (RNAi) to silence these genes. Two RNAi constructs, VcFD-RNAi and VcTFL1-RNAi, were introduced into the northern highbush blueberry (Vaccinium corymbosum) cultivar ‘Aurora’ via Agrobacterium tumefaciens-mediated transformation. Phenotypic analysis of first-generation (T0) transgenic plants accessed flowering time, architecture, fruit and leaf bud development, plant height, and branching. Preliminary results revealed that VcFD-RNAi plants produced fewer shoots, while VcTFL1-RNAi plants exhibited reduced branching per shoot compared to nontransgenic ‘Aurora’ controls. Significant differences in leaf bud number were also observed between nontransgenic and transgenic lines. VcFD-RNAi plants were smaller than nontransgenic ‘Aurora’ plants, whereas no significant size difference was detected between VcTFL1-RNAi and wild-type plants. Transcriptomic comparisons between nontransgenic ‘Aurora’ and transgenic lines revealed differentially expressed genes (DEGs). The VcFD-RNAi vs. nontransgenic ‘Aurora’ identified 2,108 DEGs, including 49 flowering-related genes, 116 genes hormone pathway genes, and 57 sugar metabolism genes. Similarly, the VcTFL1-RNAi vs. nontransgenic ‘Aurora’ uncovered 2,030 DEGs, with 52 flowering-related, 111 hormone-related, and 55 sugar-metabolism-associated genes. Ongoing analyses of these DEGs aim to elucidate the molecular mechanism underlying VcFD- and VcTFL1-mediated flowering regulation of flowering and development in blueberry. This study will reveal the functional roles of VcFD and VcTFL1, offering potential targets for genetic improvement of blueberry architecture and yield.

Botrytis cinerea is the second most economically important fungal phytopathogen causing gray mold disease. Multiple fungicide-resistant B. cinerea strains have also been reported, especially in strawberries, raspberries, grapes, and tomatoes. RNA interference (RNAi) is a post-transcriptional gene silencing mechanism in all known eukaryotes. The exogenous application of dsRNAs to knock down the target organism's essential genes is called spray-induced gene silencing (SIGS). This non-transgenic SIGS-based approach has emerged as an appealing alternative biofungicide. Despite the great potential of sprayable RNAi-based pesticides, this innovative technology encountered challenges. The low stability and the limited uptake efficiency of dsRNA are significant challenges facing SIGS. Nanomaterials-based delivery systems and structured modification of dsRNA molecules could be innovative SIGS approaches for improving its stability, uptake efficiency, and biofungicidal efficacy. This study aims to develop sprayable RNAi (SIGS) solutions by modifying dsRNA structure and using chitosan-based nanoparticles to control fungicide-resistant B. cinerea. Chitosan nanoparticles (CNPs) were generated using ionic gelation, and different forms of double-stranded RNA (dsRNA), either linear or secondary-structured, were loaded into them. The positive charges from the amine groups present in chitosan facilitated the self-assembly of the CNPs-dsRNA complex through electrostatic attraction. The stability of CNPs-dsRNAs complexes was evaluated ex-vivo by incubating naked-dsRNAs and complex-dsRNAs with the RNase A. Gel retardation assay revealed that CNPs-dsRNA complex of either linear or secondary structured-dsRNAs exhibited substantial protection of dsRNA from RNase A degradation for up to 72 hours, suggesting its potential for improving stability and long-lasting efficacy. The CNPs-dsRNAs significantly reduced the mycelial growth of wild-type and fungicide-resistant B. cinerea isolates. The results from this study indicated that chitosan-based polymer could be an effective delivery technology for both linear and secondary-structured dsRNA and hold great promise for the management of gray mold diseases.

Bacterial wilt (BW), caused by the soil-borne vascular bacterium Ralstonia solanacearum (Rs) species complex (RSSC), is one of the most devastating diseases affecting tomato and many other economically important crops. Rs infection leads to quick wilting and eventually plant death. Unfortunately, tomato bacterial wilt resistance genes have not been identified yet. Our previous study identified a candidate resistance gene from Hawaii 7996, a highly resistant tomato cultivar, that appears to be associated with qualitative resistance to bacterial wilt. Overexpression of the allele from Hawaii 7996 resulted in enhanced resistance in Heinz 1706, a model bacterial wilt susceptible cultivar. Gene editing-assisted gene knockout of the allele in Hawaii reduced bacterial wilt resistance. Yeast two-hybrid assay revealed a potential kinase that interacts with this resistance gene. The identification of the resistance gene and its interacting partner provide a better understanding of the resistance mechanisms and can be used for tomato bacterial wilt resistance breeding.

Manipulating the expression of flowering pathway genes holds potential for regulating tomato fruit productivity. SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1) is a MADS-box gene that serves as a key integrator in the flowering pathway. In this study, two full-length SOC1 genes cloned from maize (ZmSOC1) and soybean (GmSOC1), along with a partial SOC1 gene from blueberry (VcSOC1K, containing the K-domain), were individually transformed into tomato for constitutive expression. Phenotypically, the expression of VcSOC1K and ZmSOC1, but not GmSOC1, led to early flowering. Most transgenic lines for all three constructs exhibited a significant increase in fruit number per plant. More importantly, compared to non-transgenic plants, all three constructs resulted in varying degrees of increased fruit production per plant, primarily through enhanced branching. At the transcriptomic level, comparative analysis of GmSOC1 revealed the broader impact of the transformed genes. The increased expression of CLF and EZA1 appears to explain the unchanged flowering time of the GmSOC1 transgenic plants, while the repressed expression of DWARF genes likely contributes to enhanced branching. Additionally, numerous genes associated with biotic and abiotic stress tolerance displayed differential expression. These findings demonstrate that constitutive expression of either full-length or partial SOC1 has the potential to enhance tomato fruit production.

Flowering dogwood (Cornus florida) is a native tree species to the Eastern US that is susceptible to powdery mildew fungus. Genetic transformation of somatic embryogenic tissue in conjunction with gene editing are molecular methods used to breed pathogen-resistant cultivars. This research investigates the most effective germination treatment in regenerating plantlets from genetically transformed somatic embryos of flowering dogwood. From somatic embryogenic callus cultures containing the reporter transgene ß-glucuronidase (GUS), we grew tissue in liquid suspension and size fractioned using sterile metal sieves of different pore sizes. We collected pro-embryogenic masses (PEMs) from the small mesh size sieve, plated PEMS onto nylon supports using vacuum, and placed the nylon supports to semi-solid maturation media for embryo development. We chose somatic embryos elongating beyond the torpedo stage with the best quality and appearance and placed them across the four germination treatments. The germination experiments evaluated four different treatment concentrations of four different plant growth regulators (PGRs), gibberellic acid (GA3), abscisic acid (ABA), 6-benzylaminopurine (BAP), and melatonin. The environmental conditions for the first experiment included fluorescent lighting (10 μmol/m²/sec), temperature at 23 ºC (±1), and a photoperiod of 16h light:8h dark. Somatic embryos growing in germination media supplemented with GA3 (1, 2mg/L) had a higher percentage of embryos showing emergence of the apical shoot meristem between the cotyledons. The next highest percentage of somatic embryos with emerging apical meristems occurred using BAP at the concentrations 0.5 and1mg/L. The second germination experiment assessed the same treatments above except used early- stage torpedo somatic embryos and the light intensity increased to 35 μmol/m²/sec. BAP at 0.5 and 1mg/L showed the highest percentage of greening cotyledons and rooting rates. However, in 60 days, all the somatic embryos died in the GA3, ABA, melatonin, and BAP germination treatments. Although we successfully developed healthy transgenic somatic embryos, converting them into plants was a major challenge. The furthest germination stage we reached was the emerging of apical shoots, where the meristem elongates and continues to primary leaf formation. The difficulty in obtaining complete conversion to plants from these transgenic somatic embryos suggests there may be unintended impacts on growth or germination based on the location of the GUS transgene in the genome. Additionally, the original transgenic embryogenic culture was eight years old prior to the germination experiments, which could have influenced embryo conversion to plants.

Spring frost is a major environmental stressor caused by sub-zero temperatures (≤ 0 °C), often accompanied by freezing dew points, and poses a substantial economic threat to fruit crops. While the frequency of spring frost events may be influenced by climate change, the severity of damage has increased in recent years. This is largely due to elevated early spring temperatures that induce precocious bloom, making developing flower buds more vulnerable to subsequent frost events. Although no bloom-delay plant growth regulator (PGR) has been fully established to date, the use of PGRs to postpone flowering and mitigate frost risk remains a highly sought-after strategy in horticultural production. Our previous research demonstrated that fall applications of ethephon can delay bloom by 3–6 days in peach (Prunus persica). However, this treatment has also been associated with severe gummosis, necrosis, and branch damage. In the present study, we employed a plant hormonomics approach to investigate the relative abundance of endogenous hormones in flower buds of ethephon-treated versus untreated peach trees. Our analysis revealed dynamic profiles of abscisic acid (ABA), auxins (e.g., indole-3-acetic acid, indole-3-acetamide, 2-oxo-indole-3-acetic acid), brassinosteroids (e.g., 28-norcastasterone), cytokinins (e.g., zeatin, kinetin, N6-isopentenyladenosine), jasmonate-related compounds (e.g., cis-12-oxo-phytodienoic acid, dinor-12-oxo-phytodienoic acid, jasmonic acid [JA], JA-phenylalanine), salicylic acid, gibberellins (e.g., GA1, GA3, GA4, GA6), and strigolactones, with distinct accumulation patterns related to chilling and heat accumulation during dormancy and in response to ethephon treatment. Among these, jasmonates exhibited a unique pattern: levels remained low during dormancy and spiked sharply near bud break, but this spike was significantly suppressed in ethephon-treated trees. Based on this observation, we hypothesized that JA biosynthetic inhibitors could serve as effective bloom-delay agents. Indeed, over two consecutive seasons (2023 and 2024), we tested two JA inhibitors—propyl gallate and antipyrine—in two peach cultivars, ‘Sunhigh’ and ‘Redhaven’. Both compounds significantly delayed bloom progression compared to untreated controls. Furthermore, in 2025, antipyrine treatment resulted in a marked reduction in flower mortality following a killing freeze, which caused 100% damage in untreated trees versus approximately 90% in antipyrine-treated trees. To the best of our knowledge, this study represents the first hormonomics-driven translational approach aimed at regulating bloom time in perennial fruit trees to enhance their resilience to climate-related frost events.

The session will feature presentations focused on the development and application of biotechnology in horticultural plants, followed by an open discussion on the topic and Plant Biotechnology Interest Group's business meeting.

Welcome and Opening (5 minutes)
Invited Oral Presentation (30-45 minutes)

• Speaker: Dr. Yosvanis Acanda, Simplot Company

Open Discussion (30 minutes)
Award Session (10 minutes)
Interest Group Business Meeting (30 minutes)

Cornus florida (flowering dogwood) is a valuable tree native to eastern North America and prized for its floral bracts and colorful foliage. However, the tree is highly susceptible to powdery mildew (PM), a common fungal disease that challenges ornamental plant production. There are bioengineering approaches to developing PM resistance that involve the introduction of genes into C. florida cells and the regeneration of plants through somatic embryogenesis (SE). SE is a process by which somatic cells have the capacity to produce embryos without sexual reproduction. In C. florida, the regeneration of transgenic somatic embryos into plants has been problematic. Our work aims to determine the impact of cold treatments on the germination of somatic embryos. We propose that short-term low-temperature treatments will improve embryo germination, considering past research has demonstrated the importance of periodic low temperatures on natural seed germination in woody plant species such as fruit trees. We cultured a transgenic line of C. florida embryogenic callus expressing a visual marker (ß-glucuronidase) and enriched for globular stage embryos. We then introduced these globular embryos into liquid suspension media allowing the embryos to proliferate pro-embryogenic masses (PEMs) needed for mass embryo production. We chose somatic embryos morphologically identical to zygotic embryos of the same stage of development for testing plant regeneration following exposure to four different temperature conditions over four different time periods. The four different temperatures included: (1) 3°C; (2) 4°C; (3) 7°C; and (4) 23°C as the control temperature. The four different time exposures to the different cold periods included 0, 2, 4, and 6 weeks. Following cold exposure for a designated time, we transferred the somatic embryos to germination media, exposing the embryos to fluorescent light at room temperature ( /-) 23°C. Successful germination of the somatic embryos was indicated by taproot elongation with the production of roots, greening of the cotyledons, emergence of the apical shoot, followed by expansion of epicotyl and primary leaves. This research will yield the first transgenic C. florida plants and enable the introduction of PM resistance using bioengineering methods.

Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (FON), remains a major threat to watermelon production worldwide. Effective management depends on accurate race identification, as resistance in commercial cultivars is race-specific. However, current bioassay-based race differentiation is unreliable due to genetic variability within isolates. While molecular identification exists for FON Races 1 and 2, confirming Race 3 has required multiple PCR reactions, making diagnostics cumbersome and inefficient. This study developed and optimized a multiplex PCR assay that simultaneously differentiates FON Races 1, 2, and 3 in a single reaction, significantly improving diagnostic speed and accuracy. FON isolates and related Fusarium species from Georgia, Florida, and South Carolina were tested to assess the assay’s sensitivity (0.5 ng/µL detection limit) and specificity. Results confirmed that the multiplex PCR effectively distinguishes FON from non-pathogenic Fusarium species while accurately identifying all three pathogenic races. This is the first successful multiplex PCR assay for FON race differentiation, providing a rapid, reliable tool for plant pathologists and diagnosticians to track the spread of virulent FON races. Given the increasing prevalence of Race 3, which lacks effective fungicidal control, this tool will support early intervention strategies to mitigate outbreaks and inform resistance breeding programs. Keywords: Fusarium oxysporum f. sp. niveum (FON), multiplex PCR, race differentiation, watermelon wilt.

Dormancy constitutes a critical regulatory mechanism in perennial plants, conferring resilience to winter stress and impacting subsequent reproductive success. While previous investigations have predominantly focused on vegetative and floral buds during the dormancy-regrowth cycle, often neglecting the potential contributions of other plant compartments, this study adopts a comprehensive, whole-tree perspective. Utilizing four-year-old, root-bagged peach (Prunus persica) trees (cv. 'John Boy') we investigated dormancy progression by analyzing carbohydrate metabolism in different tissues relative to accumulated chilling units (CU) and growing degree hours (GDH). Our results demonstrated that roots maintained the highest starch reserves during endodormancy; however, soluble sugar accumulation in roots appeared largely independent of local starch hydrolysis, indicating potential translocation from distal storage tissues. This hypothesis is supported by the concomitant decline in starch content in branches and stems, which coincided with increased soluble sugar accumulation in these tissues. As dormancy progressed, soluble sugars were progressively redistributed, reaching peak concentrations in roots at the onset of ecodormancy and exhibiting a more uniform distribution across tissues during ecodormancy. A significant increase in floral bud soluble sugars preceding budbreak, without a corresponding starch depletion, suggests an enhanced capacity for carbohydrate uptake. Transcriptomic analysis of root tissues across all dormancy stages identified two key gene modules (ME) exhibiting inverse correlations with carbohydrate levels. Genes within ME3, associated with starch accumulation, were significantly enriched in fatty acid metabolism pathways—including SBE2, DBE1, FAD8 and KAS1. Notably, the upregulation of FAD8 during ecodormancy suggests increased membrane fluidity, potentially facilitating carbohydrate transport. Conversely, ME10 genes, associated with soluble sugar levels, displayed enrichment in hormone signaling and carbohydrate metabolism pathways—including SUS3, BAM6, and GH9A1. These findings underscore the coordinated regulation of carbohydrate metabolism and membrane lipid composition during dormancy transitions and bud break. Furthermore, the data indicate that starch catabolism in branches and stems during chilling accumulation serves as a source of soluble sugars for roots, which in turn may sustain metabolic activity and contribute to dormancy release in buds. Future research employing this whole-tree system is warranted to elucidate the comprehensive roles of roots and other storage organs in the regulation of dormancy.

Cucumber (Cucumis sativus L.) is an economically important crop and is widely cultivated throughout the world. Cucumber plants often suffer from biotic and abiotic stresses during the whole development life cycle, which lead to reduction in yield and quality. Improvement of cucumber for disease, insect, or nematode resistance and other horticultural traits with conventional strategy is limited by long breeding cycle, narrow genetic basis, and severe incompatibility barriers in related species. Emerging plant genome editing techniques provide trait specific breeding for enhancement of plant yield, quality, stress tolerance, and disease resistance. Highly efficient regeneration and transformation system is a prerequisite for cucumber genome editing. We report an efficient Agrobacterium mediated cucumber CRISPR-Cas9 transformation system with the aid of GFP visual selection. Cotyledons from 7 days old in vitro seedlings were harvested, and inoculated with Agrobacterium tumefaciens strain GV3101 contains a binary vector with CRISPR-Cas9 gene, GFP visual selection maker and hygromycin resistance genes. Transgenic callus and shoots obtained with GFP visual selection with high efficiency. PCR double check confirmed transgenes in transgenic plants. Transgenic plants are phenotyping in the greenhouse.

A forum for discussion of potential collaborations with regards to technology in horticulture – i.e. biotechnology, UAVs, cameras, sensors, artificial intelligence, etc.