1a.Objectives (from AD-416):
To enhance knowledge of the synthesis and role of diphospho- and tri-phospho inositol phosphates during plant and seed development.
1b.Approach (from AD-416):
Diphospho- and triphospho-inositol phosphates will be characterized in plant and seed tissues during development and in response to abiotic stress. Genes and enzymes that are important to diphospho- and triphospho-inositol phosphate metabolism will be characterized. Work would primarily involve maize, barley and the model system Arabidopsis. Genomic and cDNA sequences encoding a target enzyme would be cloned and recombinant proteins would be expressed using a heterologous system like E. coli. The recombinant proteins would be used to characterize each enzymes’ biochemical properties. This includes substrate specificity and catalytic property/inhibitor-effector analyses. Mutations in selected genes will be isolated using the forward genetics approach called “TILLING”. Plant homozygous for mutations will be studied to determine the role and importance of genes.
This work contributes to National Program 301, Component 3, Crop Biological and Molecular Processes, Problem 3A, Fundamental Knowledge of plant biological and molecular processes. This project is part of an NSF-funded cooperation between the USDA-ARS, North Carolina State University, Virginia Tech and Michigan Tech that focuses on a novel class of compounds in plants, the diphospho- and triphospho-inositol phosphates. These compounds are synthesized from phytic acid, a seed phosphorus storage compound who’s synthesis and metabolism are a major focus of the parent project. A second main objective of the parent project is to increase knowledge of the molecular biology important to phosphorus biology. The diphospho- and triphospho-inositol phosphate compounds that are the focus of this subordinate project derive from phytic acid, are believed to be important to phosphorus sensing and regulation pathways, and are important to “metabolic status sensing” which plays a part in how plants sense and respond to stress such as cold stress or drought stress. Progress has been made in several components of the overall project. The USDA-ARS participant assisted project participants in Virginia and North Carolina in the use of HPLC methods of analysis. The first runs of purification and analyses of these compounds was conducted. Results were analyzed and new plans were made for follow-up work. Progress was made in the isolation of alleles of genes important to these pathways.