Submitted to: Mycopathologia
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/2002
Publication Date: 10/5/2002
Citation: Guo, B., Luo, M., Dang, P. M., Coy, A. E., Dong, W., Holbrook, Jr., C. C., Lee, R. D., Widstrom, N. W., Niedz, R. P., Lynch, R. E. 2002. Identification and characterization of resistance mechanisms to preharvest aflatoxin contamination and EST/microarray programs in corn and peanut [abstract]. In: Proceedings of the 2nd Fungal Genomics, 3rd Fumonisin Elimination and 15th Aflatoxin Elimination Workshop, October 23-25, 2002, San Antonio, Texas. p. 133 Interpretive Summary:
Technical Abstract: Corn and peanut become contaminated with aflatoxins when subjected to prolonged periods of heat and drought stress. To meet the challenge of prevention of preharvest aflatoxin contamination, it will be necessary to have a more detailed understanding of the organization and function of the genetic material of corn and peanut in response to environmental stresses. The genes that control functions leading to plant reaction to the environmental stress and fungal infection must be identified. Our research studies are focusing on identification of resistance genetic sources and characterization of the resistance mechanisms. Drought tolerance, for example, may be determined by many genetic factors. The "one-gene-at-a-time" approach for analyzing gene function is inadequate. It is now possible to locate multiple genes of plants in responding to environmental stresses. There are several major new molecular tools used for gene functional analysis, such as Expressed Sequence Tag (EST) and Micro-Array technology. Research progress has been made in our laboratories in genetic evaluation and selection for drought tolerant germplasm and gene identification and characterization. Over 600 single crosses of corn made in 2001 have been evaluated for drought tolerance, aflatoxin contamination and yield performance in 2002. Several F1s have been selected for large scale field test in 2003. We have concluded that LCB insect damage significantly increased aflatoxin production in peanut. The drought tolerant peanut lines have higher phytoalexin concentration and lower aflatoxin contamination than the drought sensitive lines. Water activity was higher in Tifton 8, the drought tolerant line, than Georgia Green, the drought sensitive line. Gene expression of PLD has been characterized in relationship with drought tolerance/sensitivity. We have initiated a new EST program in Tifton to acquire expressed gene sequence information in order to rapidly identify genes and understand their functions in whole genome level in response to drought stress and fungal infection. Exciting information has been acquired, such as some plant defense genes identified via EST as gene of small cysteine-rich antifungal protein, Ca2+/H+-exchanging protein, peroxidase, 14-3-3-like protein, glutathione S-transferase, and trypsin inhibitor.