Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: October 28, 2005
Publication Date: October 28, 2005
Citation: Jeffers, D., Krakowsky, M.D., Williams, W.P., Bertran, J. 2005. Response to aflatoxin of CIMMYT germplasm in Southern USA [abstract]. In: Proceedings of the Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop, October 23-26, 2005, Raleigh, NC. p. 82. Interpretive Summary: not required
Technical Abstract: The demand for safe, nutritious corn requires efforts to develop improved hybrids with better food processing and nutritional qualities. Exotic white lines represent a source of genes for quality traits. The International Center for Maize and Wheat Improvement (CIMMYT) has developed germplasm more tolerant to abiotic and biotic stresses, targeting aflatoxin in prone areas in Africa. Our objective was evaluate the response of selected CIMMYT white and yellow corn inbreds and hybrids to aflatoxin contamination in Southern USA and to determine the genetic variability that exists for resistance to Aspergillus ear rot in CIMMYT germplasm for use by US investigators, CIMMYT, and their network of partners to develop maize varieties with improved grain quality and storability. Twenty five CIMMYT yellow hybrids, twenty five white hybrids, twenty four white inbreds and twenty eight yellow inbreds were or are currently being evaluated at Texas, Mississippi and Georgia. These inbreds and hybrids were selected because their low Aspergillus flavus ear rot incidence in field trials under inoculation in Mexico. Evaluations in 2005 in the U.S. were artificially inoculated with Aspergillus flavus isolate NRRL3357 two weeks after flowering using the silk channel method in Starkville, MS and the colonized kernel method in Weslaco, TX. Quantification of aflatoxin was conducted using the Vicam Aflatest (Watertown, MA). There were significant differences for aflatoxin content in both inbreds and hybrids. White and yellow inbreds were evaluated in Starkville, MS. Some of them did not flowered early enough and no aflatoxin data was collected. Average aflatoxin concentration was 608 ng g-1 for white inbreds and 451 ng g-1 for yellow inbreds. White inbred CML142 and yellow inbred CLQ-G2507 had aflatoxin contents below the resistant checks, Mp313E and Mp717, respectively. Average aflatoxin concentrations for white hybrids were 148 ng g-1 in Starkville, MS and 17 ng g-1 in Weslaco, TX. Apparently, environmental conditions were not conducive of aflatoxin production with the colonized kernel method used for inoculation in Weslaco. Several white hybrids (e.g., CML341 x CML254, CML341 x CML495) had lower aflatoxin than the most resistant check. Average aflatoxin concentrations for yellow hybrids were 83 ng g-1 in Starkville, MS and 38 ng g-1 in Weslaco, TX. Yellow hybrids CML-451 x CL-02844 and CL-02450 x CML454 had smaller aflatoxin contents than resistant checks in Starkville, MS. Less variation for aflatoxin was observed in Weslaco, TX. Overall, significant differences for aflatoxin concentration were observed for both CIMMYT white and yellow maize inbreds and hybrids. There is apparent genetic variation for response to aflatoxin among exotic CIMMYT germplasm. Some CIMMYT inbreds and hybrids had aflatoxin concentrations similar to the most resistant checks. Multilocation and multiyear evaluation would be needed to select the most promising germplasm to introduce and introgress in U.S. breeding programs.