Location: Corn Host Plant Resistance Research2012 Annual Report
1a. Objectives (from AD-416):
The objectives of this proposal are: (1) to evaluate aflatoxin, yield, and agronomic traits of the new high yielding TAES experimental hybrids for a second year; (2) to conduct large scale strip tests of S2B73BC x BC300 and S1W x CML343 for yield, aflatoxin level, and agronomic traits in TX; (3) to develop and advance new lines toward producing low-aflatoxin corn hybrids; and (4) to participate in SERAT tests. The results from this research will help the seed industry to commercialize the new germplasm and lead to the release of new inbred lines and hybrids with multiple stress tolerance and adaptation to Texas and southern states.
1b. Approach (from AD-416):
Corn hybrids developed by Texas Agricultural Experiment Station and other widely grown hybrids will be grown at locations in Texas and Mississippi under different degrees of drought stress. At some locations the hybrids will be inoculated with Aspergillus flavus. Data will be recorded on flowering date, plant height, lodging, and other agronomic traits. Mature ears will be hand harvested and rated for ear mold and insect damage. Grain will be analyzed for aflatoxin contamination. The proposed research will help to identify multiple stress resistant corn and provide the germplasm and information needed by the seed industry to develop and commercialize hybrids with resistance to aflatoxin contamination.
3. Progress Report:
Aflatoxin contamination of corn by Aspergillus (A.) flavus is a chronic problem in the southern United States where a hot and dry environment stresses the plants and increases aflatoxin production. Aflatoxin is particularly serious in drought-susceptible hybrids under dry and hot environments. Ear damage by corn earworms increases aflatoxin accumulation. Producers need new hybrids that are adapted to southern environments and resistant to aflatoxin contamination. The strategy for breeding aflatoxin resistant corn is to improve drought and heat tolerance, improve corn earworm resistance, and stack the resistance genes from known aflatoxin resistant sources such as MP715 into germplasm adapted to southern environments. The objectives of this study were to (1) develop multiple-stress tolerant corn inbred lines and hybrids to reduce aflatoxin contamination; (2) produce near isogenic lines (NILs) for validating aflatoxin resistance quantitative trait loci (QTLs). A study involving 46 experimental and four commercial hybrids was evaluated for aflatoxin, yield, and agronomic traits in Dumas, Halfway, Lubbock, College Station, Corpus Christi, and Uvalde in Texas and at Mississippi State, MS, in 2011. The experimental hybrids were the testcrosses of the lines derived from the cross between teosinte and corn (Teo-lines). These testcrosses of Teo-lines yielded close to the commercial hybrids. Several of these experimental hybrids had significant low aflatoxin. Six of these experimental hybrids are currently tested by a seed company in multiple locations for potential commercialization. This test is repeated in 2012. The Southeastern Regional Aflatoxin Test (SERAT) was conducted at Halfway, TX, in 2011. Among the 30 entries, nine were from our breeding program. A few entries from this project had low aflatoxin and high yield. Three lines (MP313E, MP715, and MP717) developed by USDA-ARS at Mississippi State, Mississippi, were used as the QTL donor source of aflatoxin resistance. The recurrent parent lines are PHW65 and PHW79 and two Texas AgriLife proprietary lines. The F1 and BC1F1 seeds were produced in 2010. BC1F1 plants were grown and backcrossed to the recurrent parents in Texas and Mississippi, in 2011 to produce BC2F1 seeds. However, the ferocious drought, devilish winds, and unrelenting heat led to poor seed setting, almost all backcrosses' ears did not produce useful seeds. One inbred line identified in previous aflatoxin studies produced high yield and had excellent grain quality. This line is now used for producing commercial hybrids.