ASHS 2024 Conference: Full Schedule

10:30am HST

PB 3 - Leaf Culture and Regeneration in Two Cultivated Strawberries (Fragaria x ananassa)

Thursday September 26, 2024 10:30am - 10:45am HST

Strawberry (Fragaria × ananassa) holds significant commercial importance as a fruit crop. Tissue culture regeneration techniques offer a promising avenue for rapid propagation, genomic study, and biotech breeding, including genome editing and genetic transformation. However, literature reports on cultivated variety-based strawberry regeneration and transformation/genome editing is limited. This study aims to investigate the influence of various tissue culture conditions on the regeneration efficiency of two major cultivated strawberry varieties, 'Chandler' and 'Festival', by assessing the impact of different culture conditions and hormonal treatments on the regeneration of selected varieties' in vitro leaf cultures. The first three open leaves from 4-week-old in vitro cultures were collected and cultured on Murashige and Skoog (MS) medium supplemented with varying concentrations of Thidiazuron (TDZ) (0, 0.5, 1, 2, 4 mg/L) combined with 2,4-dichlorophenoxyacetic acid (2,4-D) (0.2 mg/L). The cultures were maintained in a growth chamber with varying light (dark/light) and photoperiod conditions. Regeneration parameters, including regeneration rate, regeneration number, and root development, were recorded over an 8-week period. Preliminary results indicate a significant influence of TDZ concentrations and light conditions on shoot regeneration rate and number. The combination of TDZ at 1 mg/L and 2,4-D at 0.2 mg/L under a 20-day dark pretreatment followed by a light (16/8-hour) condition resulted in the highest regeneration efficiency. Rooting was observed when the cultures were transferred to a hormone-free MS medium.

Speakers

Kedong Da

North Carolina State University

Director of plant transformation lab at North Carolina State University

Co-authors

Anna Nelson

NC State University

Calyssa Stevenson

North Carolina State University

Ezra Kinsch

North Carolina State University,

Gina Fernandez

NC State University

Huani Leng

North Carolina State University

Keren Molina Morale

NC State University

Sydney McLennan

North Carolina State University

Tianbao Yang

USDA-ARS

Wusheng Liu

North Carolina State University

Thursday September 26, 2024 10:30am - 10:45am HST
Nautilus 1

Oral presentation (Individual talk), Plant Biotechnology 3

SUBJECT Plant Biotechnology

10:45am HST

PB 3 - Leaf Culture and Regeneration in Hydrangea Macrophylla

Thursday September 26, 2024 10:45am - 11:00am HST

Nautilus 1

Hydrangea is a genus of flowering plants that includes a diverse range of species and cultivars. These plants are known for their large, showy flower heads and are commonly grown as ornamental shrubs in gardens and landscapes. Hydrangea macrophylla, commonly known as bigleaf hydrangea, is a popular ornamental shrub in the hydrangeaceae family, well-known for its large, showy flower heads and broad leaves. Tissue culture regeneration techniques offer a promising avenue for rapid propagation, genomic study, and biotech breeding, including genome editing and genetic transformation. However, literature on hydrangea macrophylla regeneration and transformation/genome editing report is limited. This study aims to investigate the influence of various tissue culture conditions on the regeneration efficiency of Hydrangea macrophylla 'Blaumeise,' 'H2020-59,' and 'H15298' by assessing the impact of different culture conditions and hormonal treatments on the regeneration of selected varieties in vitro leaf cultures. The first three open leaves from 4-week-old in vitro cultures were collected and cultured on Murashige and Skoog (MS) medium, supplemented with varying concentrations of 6-Benzylaminopurine (BAP) (0, 0.5, 1, 2 mg/L) combined with 1-Naphthaleneacetic Acid (NAA) (0.01 mg/L). The cultures were maintained in a growth chamber with varying light (dark or light) and photoperiod conditions. Regeneration parameters, including regeneration rate, regeneration number, and root development, were recorded over a 4-week period. Preliminary results indicate a significant influence of BA concentrations and light conditions on shoot regeneration rate and number. The combination of BA at 2 mg/L and NAA at 0.01 mg/L under dark conditions resulted in the highest regeneration efficiency. Rooting was observed when the cultures were transferred to a hormone-free MS medium.

Speakers

Kedong Da

North Carolina State University

Director of plant transformation lab at North Carolina State University

Co-authors

Anna Nelson

NC State University

Callie Nix

North Carolina State University

Huani Leng

North Carolina State University

John Nix

NC State University

Keren Morales

NC State University

Sydney McLennan

North Carolina State University

Thomas Ranny

North Carolina State University

Wusheng Liu

North Carolina State University

Thursday September 26, 2024 10:45am - 11:00am HST
Nautilus 1

Oral presentation (Individual talk), Plant Biotechnology 3

SUBJECT Plant Biotechnology

11:00am HST

PB 3 - Immature Embryo Germination of Camellia sinensis (L) O. Kuntze.

Thursday September 26, 2024 11:00am - 11:15am HST

Nautilus 1

Camellia sinensis (L.) O. Kuntze is a woody perennial, evergreen shrub or small tree native to Southwest China, whose leaves are processed into various types of teas for consumption. Harvesting mature tea seeds typically requires 12 to 14 months, with an additional 2 to 3 months needed for germination using traditional methods. In an effort to expedite this breeding cycle, we conducted aseptic germination experiments on immature embryos of Camellia sinensis fruits collected from different months, spanning from May to September. Visible embryos were observed in immature fruits harvested in late July, exhibiting an average size of 2.17 ± 0.33 cm, and demonstrated germination capabilities only after mid-August. These embryos were excised and cultured on Murashige and Skoog (MS) medium supplemented with 3% sucrose and 0.65% agar. Cultures were maintained in a growth chamber set at 24°C under a 16-hour photoperiod. To enhance the germination process, cultures were kept in darkness for the initial two weeks. Immature embryos initiated germination approximately one to two weeks after the initiation of culture. After two months, plantlets were transplanted into a substrate consisting of peat moss and perlite (1:1 v/v) and acclimatized in a mist system within a greenhouse. Five month post-culture initiation, the average shoot length, root length, and leaf number of transplanted plantlets were recorded as 2.24 ± 0.89 cm, 5.61 ± 4.58 cm, and 8.36 ± 2.84, respectively. Preliminary findings suggest promising outcomes, demonstrating the feasibility of in-vitro embryo germination in tea plants. This methodology holds the potential to mitigate late-term abortion of hybrid embryos and significantly shorten the breeding cycle, critical aspects in breeding triploid tea varieties through crossbreeding diploid and tetraploid tea plants.

Speakers

Sarita Paudel

University of Georgia

Co-authors

Donglin Zhang

University of Georgia

Thursday September 26, 2024 11:00am - 11:15am HST
Nautilus 1

Oral presentation (Individual talk), Plant Biotechnology 3

SUBJECT Plant Biotechnology

11:15am HST

PB 3 - Development of an In Vitro Transformation System for Gene Editing Powdery Mildew Resistance in Gerbera jamesonni

Thursday September 26, 2024 11:15am - 11:30am HST

Nautilus 1

Gerbera is among the significant players in the global cut flower market, valued at 30 billion USD in 2023. Gerbera daisies, along with chrysanthemums are the largest segment of the cut flower market with a share of 40%. The quality and quantity of gerbera cut flower production is negatively impacted by the fungal disease powdery mildew causing a significant loss of revenue. Effects from powdery mildew infection include reduced flower quality, stunted growth, decreased flower longevity, and decreased marketability. Powdery mildew is currently controlled using fungicides which increases the cost of cut flower production and has the potential for the fungus to develop resistance to the fungicides. One strategy is to use gene editing and CRISPR technology to produce gerbera plants resistant to powdery mildew. The gene “mlo” which stands for “Mildew Locus O” plays a crucial role in the plant’s defense against powdery mildew infections. Plants with mutations in the “mlo” gene exhibit a type of broad-spectrum resistance providing protection against various strains of powdery mildew. We developed a tissue culture regeneration and transformation system for the Gerbera jamesonii cultivar ‘Flori Line Maxi Yellow’ which is sensitive to powdery mildew. The Agrobacterium tumefaciens strain GV3101 containing a binary plasmid encoding for an enhanced GFP marker gene and hygromycin selection gene was used to develop the transformation system. Young, 10mm sized in vitro leaves with part of the petiole were used as explants. A sensitivity test with the explants showed hygromycin at 7.5 mg/L was optimal for selection of callus with positive GFP expression. The next step is to regenerate GFP plants to confirm successful transformation and design CRISPR constructs to inactivate the “mlo” gene in the powdery mildew sensitive gerbera cultivar via gene editing.

Speakers

Heather Gladfelter

University of Georgia

Co-authors

Dayton Wilde

University of Georgia

Khuram Tanveer

University of Georgia

Thursday September 26, 2024 11:15am - 11:30am HST
Nautilus 1

Oral presentation (Individual talk), Plant Biotechnology 3

SUBJECT Plant Biotechnology

11:30am HST

PB 3 - Declining Phosphorus Availability Increases Sucrose Synthase Activity and Storage Root Formation in Sweetpotato cv Beauregard Adventitious Roots

Thursday September 26, 2024 11:30am - 11:45am HST

Nautilus 1

Sucrose Synthase (SuSy) plays a crucial role in sugar metabolism mainly in the sink tissues of plants. In sweetpotato, increased SuSy activity has been associated with increased storage root development and correlated with sink strength. However, little is known about the specific variables associated with increased SuSy activity. Evidence from model systems supports the hypothesis that phosphorus (P) starvation is associated with increased accumulation of carbohydrates in roots. In the first study, we measured SuSy gene expression in ‘Beauregard’ sweetpotato grown in a split root system and subjected to the following P treatments: positive control ( / ), negative control (0/0), declining P (-/-), and split P ( /-). The declining P treatment corresponded to 25, 50, 75 and 0% progressive reduction in P and was imposed on days 6, 9, 12, and 15, respectively. A second study was conducted to measure storage root development at 50 days. The (-/-) treatment was associated with increased SuSy activity in developing adventitious starting at 11 days after planting. Moreover, plants grown with the declining P treatment produced storage roots with larger diameter (>2cm) significantly higher than the positive control. Decreased SuSy activity was associated with reduction in storage root number among P-deficient (0/0) plants. Taken together, these results support the hypothesis that P availability in the root zone is associated with sink strength and storage root formation signaling in adventitious roots. These findings can be used to develop tools and management practices to increase P fertilizer efficiency for consistent storage root yields in sweetpotato.

Speakers

Oral presentation (Individual talk), Plant Biotechnology 3

SUBJECT Plant Biotechnology

ASHS 2024 Conference

10:30am HST

Kedong Da

Anna Nelson

Calyssa Stevenson

Ezra Kinsch

Gina Fernandez

Huani Leng

Keren Molina Morale

Sydney McLennan

Tianbao Yang

Wusheng Liu

10:45am HST

Kedong Da

Anna Nelson

Callie Nix

Huani Leng

John Nix

Keren Morales

Sydney McLennan

Thomas Ranny

Wusheng Liu

11:00am HST

Sarita Paudel

Donglin Zhang

11:15am HST

Heather Gladfelter

Dayton Wilde

Khuram Tanveer

11:30am HST

Marissa Barbosa

Arthur Villordon

Cole Gregorie

Don La Bonte

Lisa Arce

Mae Ann Bravo