CoPIs: Johar Singh (Punjab Agricultural University, Ludhiana, India) and Devinder Sandhu (University of Wisconsin-Stevens Point)
Key Collaborators: Kanwarpal S. Dhugga (Pioneer Hi-Bred International, Inc.), Gurmukh S. Johal (Purdue University), Mustafa Shafqat (COMSATS University, Abbottabad, Pakistan), Harindra S. Balyan and Pushpendra K. Gupta (Meerut University, India), and Madhu Meeta Jindal (Punjab Agricultural University, Ludhiana, India)
Genes influencing plant height have revolutionized agriculture by doubling the wheat and rice production. Under conditions of environmental stress, the most predominantly used wheat semi-dwarf mutants rht1 and rht2 exhibit adverse effects on agronomic traits including coleoptile and first leaf length, root length and biomass, as well as drought tolerance. These adverse effects limit wheat yields under abiotic stress conditions that regularly affect more than 85% of the US and about 50% of the world wheat production area. The main goal of the project is to identify and characterize an alternative dwarfing gene system for wheat and other cereals in order to alleviate adverse effects of the currently used dwarfing genes. Currently used dwarfing gene systems in wheat reduce plant height by interrupting production or signaling of plant growth hormone gibberellins that are particularly important for plants to deal with stressful conditions. Previous studies have shown that mutations in the maize brachytic2 (br2) and the sorghum dwarf3 (dw3) genes that encode P-glycoproteins (PGPs) involved in polar transport of auxin, result in a reduction in plant height without any of the adverse phenotypic effects usually associated with the currently used wheat dwarfing mutants. Based on these observations, this project will test whether the wheat ortholog (TaBr2) of the maize Br2 gene can be used as an alternative dwarfing gene system in wheat. Specific objectives are to clone TaBr2 and to study its expression and function in wheat using various reverse genetics tools including virus-induced gene silencing and RNAi. In addition, mutations in TaBr2 will be isolated using phenotypic as well as by TILLING screens in order to identify the ideal dwarfing mutant.
The benefit of the project, especially to farmers with small land holdings, will come from the introgression of value-added genes, including stripe rust resistance genes as well as newly-developed dwarfing gene mutants, into popular varieties of India, Pakistan, and the US. In addition, the project will provide new insight into the process of auxin signaling and transport in crop plants.
The project will provide highly interdisciplinary and international research training opportunities for undergraduate and graduate students, as well as for research associates/visiting scientists. The PIs are actively involved in outreach activities including farmers' Field Days, talking to grower groups and organizing lab demonstrations and displays to grower groups and the public at large. The project information and findings will be communicated with the public via these efforts as well as through electronic means. A project website will be developed that will serve as a "one-stop" location for access to all resources generated in this project. Links will be provided to this project webpage from each of the investigator's web pages as well. Expression and sequence data will be immediately submitted to GenBank (www.ncbi.nlm.nih.gov/), according to the currently accepted community standard (e.g. Bermuda/Ft. Lauderdale agreement). Real-time expression data of selected genes on various wheat lines will be made freely available first via publications and then by hosting on the project webpage and on Gramene (www.gramene.org/). Mapping data will be available at GrainGenes database (http://wheat.pw.usda.gov/GG2/index.shtml). All VIGS and RNAi constructs and germplasm generated in this project will be maintained in the PIs' lab and will be available to the public. Gene introgression lines developed in India and Pakistan will be released as public varieties after going through variety testing programs of the respective countries. Introgression lines developed in the US will be released as public varieties, possibly through the USDA-ARS National Center for Genetic Resources Preservation and the Plant Variety Protection Office.
