Research area: Application of conventional breeding & selection methodologies to improve drought and salt tolerance in alfalfa. Application of genomic strategies to manipulate forage yield heterosis and to identify key loci controlling drought and salt tolerance in alfalfa.
IMPROVING OSMOTIC STRESS TOLERANCE IN ALFALFA THROUGH MOLECULAR TECHNIQUES AND CONVENTIONAL BREEDING.
We are focusing on three approaches to improve osmotic stress tolerance in alfalfa: 1) metabolic engineering with genes that produce osmoregulatory compounds and reactive oxygen species (ROS) scavenging enzymes, 2) developing genomic strategies to identify key loci controlling drought tolerance, and 3) conventional breeding and selection for improved drought tolerance.
Under salt and drought stress many plants accumulate low molecular weight compounds, such as sugar alcohols, to help cells adjust to low water potentials. Under stress, ROS may damage specific stromal enzymes of the Calvin-cycle. We are evaluating stress tolerance response in alfalfa that has been transformed with multigene cassettes containing enzymes that produce osmoltye compounds and that scavenge ROS.
Genetic characterization of complex crop traits, such as drought tolerance, is now feasible using gene expression profiles based on high density arrays of plant cDNAs. We are initiating a project to rapidly generate a large collection of drought-responsive genes from alfalfa by screening cDNA microarrays that are available in related legume species. Those arrayed cDNAs, from legume species, which hybridize as drought-responsive to control and drought-stressed alfalfa labeled cDNAs will be identified. Our hypothesis is that drought responsive genes are candidate genes for the quantitative trait loci (QTL) influencing drought resistance in alfalfa. Drought-responsive cDNAs will be developed into allele specific markers, mapped, and placed on an AFLP linkage map that we have developed. These markers will subsequently be evaluated for their associations with QTL influencing drought tolerance in tetraploid alfalfa.
We are also actively involved in developing drought tolerant alfalfa cultivars and germplasms and in describing genetic associations between agronomic, morphological, and water-use efficiency traits in alfalfa under irrigated and drought conditions. Our field data indicate that some drought tolerant phenotypes appear to rely on deep rooting mechanisms to escape drought. Others appear to rely on turgor maintenance through osmotic adjustment or stomatal regulation. These different phenotypes provide ideal genetic material for further molecular and physiological characterization of drought tolerance response in alfalfa.
Research Positions and Employment:
Current Research Emphasis:
Genetic characterization and improvement of drought/salt tolerance in alfalfa through molecular techniques and conventional breeding approaches. Courses Taught
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