To support the Society’s vision to encourage education and scientific informational exchange and recognize outstanding post docs, the Plant Biotechnology Section held a Plant Biotechnology Post-doctoral Oral Presentation Competition on Sunday June 11th. A panel of judges evaluated the presentations using the following criteria: experimental design, data analysis, proper interpretation of the results, originality of the study, technical difficulty, appearance and ability of the post-doctoral candidate to present it. The judges were Dr. Nirmal Joshee from the Fort Valley State University, Dr. Prakash Kumar from the National University of Singapore and Dr. Geny Anthony from Dow Agrosciences. Dr. Zhifen Zhang from the Department of Horticulture, UGA Tifton Campus received the first prize for his talk Improving Agrobacterium-mediated Transformation of Cowpea (Vigna unguiculata L.)” followed by Dr. Tianhong Yang (second prize) from Arkansas Biosciences Institute, Arkansas State University for his talk “Enhanced Production of Prenylated Stilbenoids and Elucidation of Their Biosynthetic Pathway in Hairy Root Cultures of Peanut”.

Submitted by Piero Barone

First PLACE AWARD

Improving Agrobacterium-mediated Transformation of Cowpea (Vigna unguiculata L.)

Cowpea is an important dietary protein source for millions of people in Africa, South Asia, and South America. Use of genetic transformation can help to develop new cowpea varieties by introducing new genetic diversity or synthesizing new biological pathways. However, production of transgenic cowpea plants remains inefficient and inconsistent. This study aims to improve the cowpea transformation method so that biological engineering of this important crop will become facile. Two regeneration methods were evaluated. Use of cotyledonary-node explants from 4-d-old seedlings could produce 3.8 shoots per explant after 2-wk culture on a shoot induction medium (SIM) containing 1.67 mg/l 6-benzylaminopurine (BA). When seeds were germinated on media containing BA, cotyledon explants from 4-d-old seedlings could produce nearly twice as many shoots per explant as those without preconditioning. Shoot organogenesis was also obtained by using cotyledonary nodes from mature seeds imbibed in sterile water overnight, producing 3.3 shoots per explant after 2-wk culture on SIM. Sonication, vacuum infiltration, needle injection and incision with scalpels at the shoot-forming region were evaluated in order to enhance Agrobacterium-mediated transformation at the target tissue. Using cotyledonary nodes from imbibed seeds, sonication for 20 s and 40 s increased the number of explants showing transformed cells at the shoot-forming region, with over 45% of explants having cells or sectors expressing a fluorescent protein transgene at the target region. The increased number of transformed cells at the shoot-forming region is being tested for improved recovery of transgenic shoots. After over 1-mo selection on 5 mg/l phosphinothricin, 0–1.4% of explants were able to produce transgenic shoots, varying among experiments. Efforts to improve shoot regeneration from transformed cells are continuing.

Zhifen Zhang, NESPAL/University of Georgia, 2356 Rainwater Rd, Tifton, GA 31793. In Vitro Cellular and Developmental Biology, 53:S33-34, 2017

 

Second Place Award

Enhanced Production of Prenylated Stilbenoids and Elucidation of Their Biosynthetic Pathway in Hairy Root Cultures of Peanut.

Peanut (Arachis hypogaea), a species from the Fabaceae (Leguminosae) family, is currently grown around world as an economically important oil and food crop. This species is capable of producing prenylated stilbenoids as phytoalexins to protect itself against various pathogens. In addition to their plant defense mechanisms, these prenylated stilbenoids are associated with a variety of biological activities which have attracted increasing interest in the field of medicine and nutrition for their potential applications in the prevention and treatment of human diseases. Despite their importance to plant and human health, the availability of prenylated stilbenoid is limited and their biosynthetic pathways remain to be elucidated. In this study, hairy root cultures of peanut were induced to produce peanut stilbenoids upon treatment with various elicitors. Co-treatment with methyl jasmonate (MeJA) and methyl-β-cyclodextrin (CD) led to sustained high levels of stilbenoids in the culture medium when compared to other elicitor treatments. Real-time quantitative PCR results showed that MeJA and CD had a synergistic effect on resveratrol synthase gene expression. This elicitor-controlled hairy root bioproduction system was further used to study the biosynthetic pathway of prenylated stilbenoids. Using metabolic inhibitors, it was demonstrated that the prenyl moiety on the prenylated stilbenoids derives from a plastidic pathway. Furthermore, the characterization, for the first time, of a membrane-bound stilbenoid-specific prenyltransferase activity from the microsomal fraction of peanut hairy roots was achieved. The characteristics of this enzyme provide important information for subsequent cloning and comprehensive definition of the prenyltransferase gene(s) of peanut.

Tianhong Yang, Arkansas Biosciences Institute, Arkansas State University, Jonesboro, AR, 72467. In Vitro Cellular and Developmental Biology, 53:S34, 2017