Progress 10/01/12 to 09/30/13
Outputs
Progress Report 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. 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. Aflatoxin contamination of corn by Aspergillus flavus is a chronic problem in the southern United States where a hot and dry environment stresses plants and increases aflatoxin production. Aflatoxin is particularly serious in drought-susceptible hybrids grown under dry and hot environments. Ear damage by corn earworm also increases aflatoxin accumulation. Producers need new corn hybrids that are adapted to the southern United States and resistant to aflatoxin contamination. The objectives of this study were to develop multiple-stress tolerant corn inbred lines and hybrids to reduce aflatoxin contamination and to produce near-isogenic lines (NILs) for validating aflatoxin resistance quantitative trait loci (QTL). One hundred twenty experimental corn hybrids were evaluated for yield and aflatoxin contamination in several locations in Texas (Dumas, Halfway, Lubbock, College Station, Corpus Christi, Uvalde, and Weslaco) and one location in Mississippi. These hybrids were produced from crosses among Mp715 derived lines, lines derived from a crosses between corn and teosinte, and other advanced lines developed at Texas A&M AgriLife Research Center in Lubbock, Texas. The Mp715 derived lines were developed from breeding crosses involving Mp715, a line with resistance to aflatoxin contamination developed by ARS scientists in the Crop Science Research Laboratory at Mississippi State, Mississippi. Hybrids were entered into the Southeastern Regional Aflatoxin Test (SERAT). The hybrids were evaluated for resistance to aflatoxin contamination, corn earworm damage, and yield at several locations across the southern United States. Results from these tests have shown that several experimental hybrids developed at the Texas A&M AgriLife Research Center not only yielded well but also had significantly lower levels of aflatoxin accumulation than the commercial check hybrids. These lines with tolerance to multiple stresses are ready for public release. Research efforts on reducing pre-harvest aflatoxin contamination were presented at a field day attended by breeders with seed companies. Several lines that have low levels of aflatoxin accumulation and excellent agronomic characteristics are being prepared for release. One of the inbred lines has been licensed to a seed company and is now used as a parental line of a commercial hybrid. This hybrid is currently widely grown in the southern United States. The hybrid produces high grain yield, has excellent grain quality, and low levels of aflatoxin contamination. Additional hybrids made with this line will be launched in the near future.
Impacts
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report 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. 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. 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.
Impacts
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report 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. 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. For the second year, 300 testcrosses produced by crossing a diverse group of germplasm lines with Va35 were evaluated for aflatoxin accumulation, corn earworm damage, and days to mid-silk. This work was conducted in cooperation with ARS at Mississippi State (6406-21000-011-00D) and a cooperator at Texas A&M University (6406-21000-011-10S). Grain samples from all locations and both years were analyzed for aflatoxin concentration at Mississippi State: some germplasm lines appear to be potentially useful sources of resistance to aflatoxin contamination. After genotyping by high throughput sequencing is completed and the results are analyzed, new genes or groups of genes associated with resistance to aflatoxin contamination should be identified. Experimental hybrids were developed from a breeding cross containing Mp715, which is a known source of resistance developed and released by ARS at Mississippi State (6406-21000-011-00D). Aflatoxin concentration was significantly different among the hybrids. The low-aflatoxin hybrids also produced grain yields comparable to the commercial checks across test locations. Evaluations continue to determine which of the newly developed lines will be released as sources of resistance to aflatoxin contamination. One study involving 35 experimental hybrids of Mp715-derived lines was conducted for a second year in Lubbock and Corpus Christi in Texas and Mississippi State, Mississippi, in 2010. Another study involving 50 crosses of teosinte-derived lines was conducted in four locations in Texas and in Mississippi State, Mississippi, in 2011. The goal is to identify low-aflatoxin corn inbred lines with good agronomic traits. Backcross populations are being developed from crosses between resistant lines, Mp313E, Mp715, Mp717, and susceptible lines, PHW65 and PHW79. These populations will be used to confirm quantitative trait loci (QTL) associated with resistance to aflatoxin accumulation. Activities were monitored through a meeting of cooperating scientists at a workshop on diseases of corn, conference calls, e-mails, written reports, and phone calls.
Impacts
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report 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. 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. Contamination of corn grain with aflatoxin, which is produced by the fungus Aspergillus (A.) flavus, is a chronic problem in the southern United States. Hot, dry environments stress corn plants and increase the accumulation of aflatoxin. Producers need corn hybrids with resistance to aflatoxin contamination. Our strategy for breeding corn with resistance to aflatoxin contamination is to improve drought and heat tolerance, increase resistance to corn earworm damage, and stack genes from known sources of resistance such as Mp715 developed and released by ARS at Mississippi State (6406-21000-011-00D) into germplasm adapted to the southern states. Experimental hybrids were developed, 28 from a breeding cross containing Mp715, and evaluated in a randomized complete block design with three replications. The Lubbock and Halfway, TX, locations had optimum and limited irrigation treatments. Plants in Lubbock, TX, and Starkville, MS, were inoculated one week after silking by injecting 3-ml conidia solution of Aspergillus flavus NRRL3357 (1.5 x 106 conidia/ml) into silk channels. Ears from each plot were hand-harvested, rated for corn earworm feeding damages and ear traits, and then threshed for grain yield. Grains were initially ground in a Romer mill at the coarse grind setting. After thoroughly mixing the ground kernels, a 200 g sub-sample was ground again at the finest grind setting on the mill. Aflatoxin B1 assay was done on 50 g sub-samples of the finely ground material for each composite replication using the Vicam immunoassay/fluorometer system. Standard ANOVA was performed to test the difference among hybrids. Natural log transformation of aflatoxin data was made before data analysis. The aflatoxin was significantly different among the hybrids. A susceptible check hybrid exhibited high aflatoxin (416 ppb). Commercial hybrid checks were also susceptible with 1155 and 456 ppb. All crosses of Mp715-derived lines with C2A554-4 generally had low aflatoxin as compared to the crosses with Tx205 and a proprietary line with Bt gene. C2A554-4 is a drought tolerant line. This result indicates that stacking aflatoxin resistant QTLs with drought tolerance can effectively reduce aflatoxin accumulation. The low-aflatoxin hybrids also produced grain yields comparable to the commercial checks across test locations. We are preparing to release these new aflatoxin resistant inbred lines. An association mapping panel consisting of the single-cross testcrosses from 300 diverse corn inbred lines was planted in Lubbock, TX, April 10, 2009, in a randomized complete block design with three replications. The plants were well watered in the entire season with a sub-surface drip irrigation. Detailed data were collected on plants per plot, plant and ear height, pollen shed and silking date, husk coverage, ear length, corn earworm feeding damage, percentage of molded kernels, and grain weight of 10 harvested ears. Activities were monitored through a meeting of cooperating scientists, administrators, producers, and scientists from commercial companies held at Mississippi State, conference calls, e-mails, written reports, and phone calls.
Impacts
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