1a.Objectives (from AD-416):
The goal of this research is to identify the major genes involved in Al tolerance in rice and provide a better understanding of the physiological mechanisms of Al tolerance. Our preliminary work demonstrates that as a species, rice is capable of growing at Al3+ activities that are between 5-15 times higher than that for maize, sorghum, and wheat, leading us to hypothesize that rice may be a source of novel Al tolerance genes.
1b.Approach (from AD-416):
1) Fine scale mapping of a novel and major rice Al tolerance QTL we have recently identified, with the goal of cloning the tolerance gene responsible for this QTL.
2) Whole genome association mapping of rice Al tolerance will be conducted via phenotyping our rice association panel for Al tolerance and genotyping the panel with the 44k rice SNP chip developed in the McCouch lab.
3) Investigate the role of cell wall proteins in rice Al tolerance via studying the effect of Al on rice cell wall properties (extensibility) using rice root cell wall preparations reconstituted with isolated rice wall proteins.
In FY 2013, the final year of the grant, we used map-based cloning techniques to clone the gene underlying a major rice aluminum tolerance QTL we had previously identified. This gene turned out to be ART1, which encodes a transcription factor, which is a type of protein that controls the expression of other genes. ART1 turns on expression of other rice Al tolerance genes when the plant is stressed by Al such as the Nrat1 gene we studied and reported on in other annual reports this year. We went on to use molecular breeding techniques to make near-isogenic lines expressing the Al tolerant and sensitive versions of the ART1 gene in both parents of the mapping population where the ART1 QTL was identified. These near isogenic lines will be useful materials for the molecular breeding of the most Al tolerant versions of ART1 to improve the Al tolerance for rice lines used for agricultural production on upland acid soils.