Submitted to: Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation
Publication Type: Abstract Only
Publication Acceptance Date: September 10, 2004
Publication Date: October 1, 2004
Citation: Guo, B., Liang, X. Q., Luo, M., Wang, M. L., Holbrook, Jr., C. C. 2004. Progress in peanut functional genomics, a strategy to mitigate aflatoxin contamination and improve other important traits. In: Proceedings of the 17th Aflatoxin Elimination Workshop, October 25-28, 2004, Sacramento, California. Technical Abstract: The peanut genome (2,800 Mb) is large in comparison to the current plant models, Arabidopsis (128 Mb), rice (420 Mb), and Medicago (500 Mb). A. thaliana was estimated to have 27,000 genes; rice is predicted to have 30,000 to 50,000 genes; and soybean is about 60,000 genes. While the peanut genome probably has a similar number of genes as the small-genome species, the large genome size makes it unrealistic to completely sequence the peanut genome in the near future. By partially sequencing large numbers of expressed genes, it is possible to obtain enough information to access genome of peanut and thus ensure continued advance in the biology of this important crop species. This project focuses solely on the expressed component of the peanut genome. The National Center for Biotechnology Information's (GenBank) dbEST database contains (June 25, 2004) 22,165,266 ESTs. There are 5,643,076 human ESTs, and 4,191,008 ESTs for mouse and rat. Among plants, Triticum aestivum (wheat) has the most ESTs deposited with 552,245 in the NCBI, and Zea mays (maize) is second with 397,515. Glycine max (soybean) has 334,668, Oryza sativa (rice) has 284,006, Arabidopsis thaliana has 258,825, and Medicago truncatula has 187,763. Peanut (Arachis hypogaea) is dramatically low on the list for such an important crop, with only 1,366 ESTs. We have generated about 2000 ESTs from two cDNA libraries constructed using mRNA prepared from leaves of peanut line C34-24 (resistant to leaf spots and tomato spotted wilt virus) and immature pods of peanut line A13 (tolerant to drought stress and preharvest aflatoxin contamination), and 1345 ESTs have been released to GenBank (CD037499 to CD038843). Four hundred unigenes have been selected from these ESTs and arrayed on glass slides for gene expression analysis, and 44 EST-derived SSR markers have been characterized for cultivated peanut, in which over 20% of the SSRs produced polymorphic markers among 24 cultivated peanut genotypes. The microarray data have been validated using real-time PCR. In the laboratory screening of the germplasm from China and India, the differences of peanut kernel infection by A. flavus were significant. Several Chinese and Indian lines had lower A. flavus colonization than Georgia Green, and this resistance has been tested in the field in 2003 and 2004. The 2003 field test supported the resistance detected in the laboratory. The protein profiles (2-D) have revealed the differences in protein contents, which may be related to the resistance observed in the laboratory and the field.