Day 2 :
Time : 09:05-09:35
Dr. Rajasekaran is a senior Research Biologist with the USDA-ARS. He obtained his B.S and M.S. from Tamil Nadu Agricultural University, India. After receiving his Ph.D. from The University of Sydney, Dr. Rajasekaran has continuously worked on the application of recombinant DNA technology towards genetic improvement of food, feed and fiber crops. He has published 135 full length publications plus 12 U.S. patents, >50 international patents, and 168 national/international conference abstracts. He serves as an Adjunct Professor in five universities. Currently his research focus at USDA-ARS is on effective control or elimination of preharvest aflatoxin contamination caused by Aspergillus spp through biotechnological means in cotton and maize .
The fungus Aspergillus flavus infects maize, cottonseed, peanut, and tree nut crops and produces aflatoxin, a highly toxic and carcinogenic secondary metabolite. Development of transgenic crops that resist fungal infection is difficult because of the complexity of the host-plant-pathogen interactions and it is more difficult to control saprophytic/opportunistic pathogenic fungi such as A. flavus. We have demonstrated in our laboratory several means of controlling the fungal growth and toxin production in transgenic cotton and maize. These include expression of a heterologous antifungal protein or synthetic peptides. For example, maize transformed with the α-amylase inhibitor protein from hyacinth bean showed reduced fungal growth and aflatoxin levels in kernel screening assays. We have also demonstrated significant anti-flavus activity with several synthetic, lytic peptides such as cecropin-based D4E1 or tachyplesin-based AGM peptides. Transgenic maize lines expressing one of these synthetic peptides AGM 182 showed significant reduction in fungal growth and toxin production (>65%). Transgenic cotton expressing D4E1 also showed antifungal properties and several field tests are being conducted for evaluation. We are currently employing host-induced gene silencing (HIGS) in which the pathogen (A. flavus) is directed by the host plant to down regulate the expression of its own gene(s) affecting its growth, invasion and/or toxin production. Significant reduction in both fungal growth and aflatoxin levels was observed in several transgenic maize lines compared to control. In this presentation examples of various transgenic approaches to control A. flavus growth and aflatoxin contamination in food and feed crops will be summarized.
Rothamsted Research, UK
Time : 09:35-10:05
Harrie Van Erp has completed his PhD from Michigan State University and Post-doctoral studies from Washington State University. He is currently a Research
Scientist at Rothamsted Research where he’s involved in research focused on “Tailoring plant lipid metabolism for nutritional and industrial purposes”.
For diverse reasons, there is a growing demand for infant formula. Traditionally infant formula is produced using vegetable
oils, which have a diff erent TAG structure than human milk fat. Th is causes digestive problems in infants. In plant oils,
16:0 is at the sn-1 and sn-3 position of the glycerol backbone, but in human milk fat, the majority (70%) of 16:0 is at the sn-2
position. In the infant’s intestine, a pancreatic lipase hydrolyses 16:0 from the sn-1 and sn-3 positions leading to the formation
of calcium soaps. Th is causes constipation and reduced uptake of nutrients and Ca2+. In recent years, several companies have
addressed this problem by using chemical technologies to change the TAG structure of plant oils. However, producing a human
milk fat substitute in plants is cheaper and better for the environment. We are using a synthetic biology approach to rationally
redesign seed lipid metabolism in order to produce vegetable oils with a similar composition and structure as human milk fat.
In my presentation, I will present data showing the progress we made in the engineering of a human milk fat substitute in crop
U.S. Department of Agriculture, USA
Time : 10:20-10:50
Dr. Grace Chen obtained her Ph.D from University of Wisconsin at Madison, and did her postdoctoral studies from University of California ̶ Plant Gene Expression Center. She has published more than 44 papers in reputed journals is globally recognized as an expert on oilseed biotechnology
Hydroxy fatty acids (HFA) from plant seed triacylglycerols (TAGs, oil molecule) are wildly used in manufacturing industrial products, such as lubricants, plasticizers and surfactants. Castor oil has 90% HFA which occupies all three sn positions of most TAGs, while lesquerella oil contains 60% HFA mostly located at sn-1 and sn-3 of TAGs. In order to improve HFA levels in lesquerella seeds, a castor lysophosphatidic acid acyltransferase 2 gene (RcLPAT2) capable of acylating HFA to the sn-2 position of TAGs was introduced into lesquerella under the control of the seed specific napin promoter from Brassica napus. Analysis of transgenic lesquerella seed TAGs showed that RcLPAT2 was able to incorporate HFA to the sn-2 position of TAG and consequently, oil accumulated more of TAGs with all three sn positions occupied by HFA. The results enhanced our understanding of plant lipid metabolism and provided invaluable guidance for future research not only for enhancing HFA content in lesquerella, but also for HFA production in other oilseed crops.