Progress 10/01/06 to 09/30/07
Outputs
Progress Report Objectives (from AD-416) The objective of this cooperative research project is to enhance the development of mycotoxin-resistant corn hybrids by identifying new resistant genes from world collections and incorporating them into existing breeding programs. Approach (from AD-416) Five steps are proposed for identifying and using new resistant genes. Step One - Select corn accessions for screening. Mr. Mark Millard, Maize Curator at the North American Plant Introduction Center in Ames, Iowa has primary responsibility to select accessions for choosing and securing seed, and for making quarantine arrangements where needed. Initial priority will be given to accessions originating from hot and dry climates where active or passive selection for resistance might have occurred. Three-hundred lines will be screened in 2003, including lines originating from the Carribean, Ethiopia, Guinea, Ghana, Mexico, South Africa, West Texas and Zimbabwe. The intent is to screen 2000 lines in subsequent years. Step Two - Inoculate corn lines in a field nursery. Dr. Steven Moore, LSU corn breeder, will conduct a field nursery at the Dean Lee Research Station in central Louisiana. A randomized complete block design will be used with two replications. Each replication will include resistant checks, including Gt-MAS:gk, Mp313e, Mp420, Mp715, and Tex6. Ears will be inoculated with A. flavus spores 10 to 14 days after anthesis using a hand-held pin bar apparatus dipped in a container containing spores in liquid suspension (90 million spores/ml). Ears will be harvested after physiological maturity and dried below 12% moisture. Harvested ears will be rated for A. flavus growth on a 0 to 9 scale, shelled, and then ground to a coarse meal and rated for bright greenish- yellow fluorescence (BGYF) on a 0 to 9 scale. Samples will then be ground to a fine meal and sent to the USDA-ARS facility at Stoneville, Mississippi for aflatoxin and fumonisin analyses. Step Three - Analyze corn lines for aflatoxin and fumonisin. Dr. Hamed Abbas, USDA Research Pathologist, will analyze corn meal samples for aflatoxin and fumonisin using commercially available assay kits distributed by Neogen Corporation of Lansing, MI (Abbas et al, 1998). Dr. Abbas will also maintain inoculum and provide spore suspensions at the time of anthesis. Resistance will be assessed by Dr. Moore. Step Four - Hybridize resistant lines. Lines showing superior resistance will be hybridized with "B73' or `Mo17' inbreds in a winter nursery to produce F1 hybrid seed to determine breeding value the subsequent year. Approximately 10 ears will be selfed and 10 ears will be cross-pollinated. Step Five - Incorporate resistant lines into breeding programs. Seed from resistant lines and hybrid seed from the same lines crossed to B73 or Mo17 will be sent to Dr, Bazou Guo at Tipton, Georgia, to Dr. Xavier Bertrand at College Station, Texas, and to Dr. Steven Moore at Alexandria, Louisiana. Seed will be tested further for resistance and incorporated into the respective breeding programs. This procedure allows for the most rapid evaluation and utilization of resistant corn germplasm feasible. Significant Activities that Support Special Target Populations This report serves to document research on Screening Global Corn Accessions to find New Genes with Resistance to Aflatoxin and Fumonisin conducted under a Specific Cooperative Agreement between ARS and Louisiana State University. Additional details of the research can be found in the report for the in-house project 6402-42000-003-00D, "Agricultural Practices, Ecological and Varietal Effects on Aflatoxins and Other Mycotoxins in Corn." New genes are needed to develop corn hybrids with resistance to Aspergillus flavus and aflatoxin biosynthesis. The first objective of this research is to uniformly screen accessions from the world collection of maize germplasm until adequate resistance is found. To date, 1900 lines obtained from the North Central Regional Plant Introduction Station in Ames, IA, have been planted at the Dean Lee Research Station in an effort to identify new resistance to aflatoxin biosynthesis. In order to increase ear size, corn lines are first crossed to B73. The F1 seed are screened for aflatoxin in the second season by inoculating ears in two replicated rows. Eleven lines were selected which may have superior resistance. These are �Nigerian Composite B�, �Manio�, �Lancaster Surecrop�, PI 218189, �Haiti 33�, �Saint Croix 1�, �Dominican Republic 309�, PI 506253, �Tx81�, �Tx807�, and PI 595535. These lines were crossed-pollinated to B73 and Mo17 in 2006 in an effort to stabilize resistance in an improved agronomic background. Seed from successful pollinations were planted in a winter nursery facility. If superior resistance is confirmed in the new lines (F4 populations), the next step will be to incorporate the resistance into commercial inbreds, probably using biotechnology tools to develop a resistant isoline. Twenty-one accessions were selected in 2006 that had lower aflatoxin mathematically than resistant checks: �CML91�, �Brazil 1135-AF�, �Brazil 1088-AF�, �BENZ 745�, �Veracruz 59�, �Jalisco 38�, �BENZ 755�, �SE 028�, �31116 G M37W2T/A�, �Veracruz 200�, �Chihuahua 230�, �Brazil 1483�, �Durango 84�, �Brazil 2797�, �Hidalgo 17�, �Veracruz 119�, �Sao Paulo Group 9�, �Chihuahua 75�, �Veracruz 130�, �Brazil 1519� and �Coahuila 21�. Seed from successful crosses and/or self-pollinations of these lines are now being moved forward in a 2007 summer nursery at the Dean Lee Research Station in Alexandria, LA. The work by the cooperator was monitored via e-mail, phone calls, visiting the collaborator by the ARS scientist on June 13 Field Day, and round table discussion at the aflatoxin workshop annual meeting in October in 2006.
Impacts
(N/A)
Publications
|
Progress 10/01/05 to 09/30/06
Outputs
Progress Report 4d Progress report. This report serves to document research conducted under Specific Cooperative Agreement between ARS and Louisiana State University. Additional details can be found in the report for the inhoue research project 6402-42000-002-00D, Agricultural Practices, Ecological and Varietal Effects on Aflatoxins and Other Mycotoxins in Corn. New genes are needed to develop corn hybrids with resistance to Aspergillus flavus and aflatoxin biosynthesis. The first objective of this research is to uniformly screen accessions from the world collection of maize germplasm until adequate resistance is found. To date, 1600 lines obtained from the North Central Regional Plant Introduction Station in Ames, IA, have been planted at the Dean Lee Research Station in an effort to identify new resistance to aflatoxin biosynthesis. In order to increase ear size, corn lines are first crossed to B73. The F1 seed are screened for aflatoxin in the second season by
inoculating ears in two replicated rows. To date, eleven lines have been selected which may have superior resistance. These are Nigerian Composite B, Manio, Lancaster Surecrop, PI 218189, Haiti 33, Saint Croix 1, Dominican Republic 309, PI 506253, Tx81, Tx807, and PI 595535. These lines were crossed-pollinated to B73 and Mo17 in 2006 in an effort to stabilize resistance in an improved agronomic background. F1 seed from successful pollinations are planned to be planted in a winter nursery facility. If superior resistance is confirmed in the new lines (F4 populations), the next step will be to incorporate the resistance into commercial inbreds, probably using biotechnology tools to develop a resistant isoline.
Impacts
(N/A)
Publications
|
Progress 09/12/03 to 06/30/05
Outputs
Progress Report Objectives (from AD-416) The objective of this cooperative research project is to enhance the development of mycotoxin-resistant corn hybrids by identifying new resistant genes from world collections and incorporating them into existing breeding programs. Approach (from AD-416) Five steps are proposed for identifying and using new resistant genes. Step One - Select corn accessions for screening. Mr. Mark Millard, Maize Curator at the North American Plant Introduction Center in Ames, Iowa has primary responsibility to select accessions for choosing and securing seed, and for making quarantine arrangements where needed. Initial priority will be given to accessions originating from hot and dry climates where active or passive selection for resistance might have occurred. Three-hundred lines will be screened in 2003, including lines originating from the Carribean, Ethiopia, Guinea, Ghana, Mexico, South Africa, West Texas and Zimbabwe. The intent is to screen 2000 lines in subsequent years. Step Two - Inoculate corn lines in a field nursery. Dr. Steven Moore, LSU corn breeder, will conduct a field nursery at the Dean Lee Research Station in central Louisiana. A randomized complete block design will be used with two replications. Each replication will include resistant checks, including Gt-MAS:gk, Mp313e, Mp420, Mp715, and Tex6. Ears will be inoculated with A. flavus spores 10 to 14 days after anthesis using a hand-held pin bar apparatus dipped in a container containing spores in liquid suspension (90 million spores/ml). Ears will be harvested after physiological maturity and dried below 12% moisture. Harvested ears will be rated for A. flavus growth on a 0 to 9 scale, shelled, and then ground to a coarse meal and rated for bright greenish- yellow fluorescence (BGYF) on a 0 to 9 scale. Samples will then be ground to a fine meal and sent to the USDA-ARS facility at Stoneville, Mississippi for aflatoxin and fumonisin analyses. Step Three - Analyze corn lines for aflatoxin and fumonisin. Dr. Hamed Abbas, USDA Research Pathologist, will analyze corn meal samples for aflatoxin and fumonisin using commercially available assay kits distributed by Neogen Corporation of Lansing, MI (Abbas et al, 1998). Dr. Abbas will also maintain inoculum and provide spore suspensions at the time of anthesis. Resistance will be assessed by Dr. Moore. Step Four - Hybridize resistant lines. Lines showing superior resistance will be hybridized with "B73' or `Mo17' inbreds in a winter nursery to produce F1 hybrid seed to determine breeding value the subsequent year. Approximately 10 ears will be selfed and 10 ears will be cross-pollinated. Step Five - Incorporate resistant lines into breeding programs. Seed from resistant lines and hybrid seed from the same lines crossed to B73 or Mo17 will be sent to Dr, Bazou Guo at Tipton, Georgia, to Dr. Xavier Bertrand at College Station, Texas, and to Dr. Steven Moore at Alexandria, Louisiana. Seed will be tested further for resistance and incorporated into the respective breeding programs. This procedure allows for the most rapid evaluation and utilization of resistant corn germplasm feasible. Significant Activities that Support Special Target Populations Progress concluded with the 2007 Annual Report, but was not terminated because of financial management reasons. See 2007 Annual Report for last reported progress.
Impacts
(N/A)
Publications
|