2012 Annual Report
1a.Objectives (from AD-416):
Make publicly available a predictive computer program for mycotoxin levels in Midwest corn and adapt as necessary for a wider range of human food use corn varieties. Use molecular biological approaches to discover, introduce, and evaluate new insect resistance genes (producing bioactive proteins and secondary metabolites), alone and in combination. Use molecular biological approaches to discover, introduce, and evaluate plant-derived selectable markers for transgnic plant production.
1b.Approach (from AD-416):
As part of the process of making the program publicly available, feedback on the
present state of the program will be sought and utilized as appropriate. An
economic module to assist in making control decisions will be developed and
incorporated. The program will be tested for utility in food grade corn by
comparing actual field collected data with predicted levels and correcting as
necessary empirically. Genes identified in the prior project that are potentially
useful in combination will be examined in model systems and further evaluated. New genes of potential use will be identified through functional targeting of cDNA, array-based technology. Molecular evolution of genes coding for resistance proteins will be utilized to further optimize efficacy against insects, while at the same time minimizing vertebrate effects. Gene product efficacy will be examined in model systems and in regenerated corn. Plant-derived genes involved in toxin resistance will be the ultimate focus of the investigation, although genes from other sources will initially be examined if appropriate plant-derived gene sequence information is not yet sufficient for cloning. Efficacy of target gene products as selectable markers and against insects, alone and in combination with insect-active genes, will be investigated.
This report documents progress for the bridging Project 3620-42000-041-00D and continues research from Project 3620-42000-040-00D which terminated in October of 2010. Progress achieved during FY12 will benefit researchers in allied fields from academia, government, and industry and will facilitate the development of corn lines with reduced levels of insect damage and fungal toxins in kernels. ARS Researchers in Peoria, IL, discovered new insect resistance mechanisms that can be integrated into corn to control corn ear insect pests and associated fungi that produce toxins. As part of studies to determine which genes are involved in lowering mycotoxin levels in popcorn, ears were collected from popcorn fields, rated for insect and mold damage, and analyzed for mycotoxins. Damaged ears were stored for future use in gene expression analysis. As part of studies to determine which insect resistance genes may be added or lost when breeding for higher yields, leaves were collected from a second series of corn inbred parent and progeny and found to have different levels of insect resistance. The leaves are being evaluated for differential gene expression in order to determine which genes may be involved in increased insect resistance. In studies designed to discover novel chemicals that defend against insects, extracts from range plants, and extracts and pure compounds from novel fungi were found to be active against agriculturally important pest caterpillars. Characterization of these compounds is ongoing. This research addresses National Program 301, Component 2: Crop Informatics, Genomics, and Genetic Analysis, Problem Statement 2C: Genetic Analyses and Mapping of Important Traits.
New protein to protect corn plants against insect pests and diseases. Identifying insect resistance genes in corn is of the utmost importance in order to maximize yield and reduce losses. However, methods for identifying such genes are laborious and time-consuming, usually taking many years to accomplish. ARS researchers in the Crop Bioprotection Research Unit, National Center for Agricultural Utilization Research, Peoria, IL, designed a protein molecule to be toxic to caterpillar and beetle pests of corn. When introduced into experimental lines of corn, it was found that the protein also enhanced resistance to fungal and bacterial diseases. The methods developed by the researchers can be used to design new resistance molecules active against both insects and plant pathogens, thereby promoting more effective and economical crop production.
Bioenergy friendly sorghum lines with altered lignin levels have enhanced resistance to pest insects. Costly energy is an impediment to the economic well being of the U.S. Production of energy sources, such as ethanol, from plant biomass has potential. ARS researchers in the Crop Bioprotection Research Unit, National Center for Agricultural Utilization Research, Peoria, IL, evaluated insect damage for two sorghum lines with low lignin levels suitable for bioenergy production compared to a genetically similar line with normal lignin. Under controlled conditions, smaller plants showed similar levels of resistance to caterpillar pests regardless of lignin levels, but larger plants from the low lignin lines had less leaf damage and their pith was more toxic to caterpillars. This information provides incentive to produce altered lignin lines for bioenergy use, ultimately resulting in reduced dependence on foreign oil and lower energy prices for industry, business, and consumers.
New insect resistance genes identified for corn. Insect damage causes hundreds of millions of dollars of losses to the corn industry in the U.S. alone. Identifying resistance genes in corn, and selectively breeding for these genes, is an economical means to mitigate yield losses. However, most of the genes that impart insect resistance are unknown. ARS researchers in the Crop Bioprotection Research Unit, National Center for Agricultural Utilization Research, Peoria, IL, identified genes in corn that contribute to resistance to caterpillars, including one gene whose function was previously unknown. This knowledge will aid breeders in developing new lines of insect-resistant corn varieties to enhance yield and quality.