Start Date: Apr 10, 2006
End Date: Sep 30, 2010
1) Sorghum represents plant species where Al tolerance is a simple trait. We have recently cloned the major sorghum Al tolerance gene, AltSB, and found it is a novel solute transporter. The function of AltSB will be studied using a multifaceted approach including the effect of increased/decreased AltSB expression on the physiology of Al tolerance, association analysis correlating sequence and phenotypic variation of multiple AltSB alleles, and analysis of AltSB transporter properties when expressed in heterologous systems. 2) Maize represents a plant species where Al tolerance is a complex, quantitative trait. We have identified a number of Al tolerance QTL in maize, and will work towards cloning these QTL via a combination of gene and protein expression analysis, high resolution mapping, and analysis of candidate tolerance genes based on homology to Al tolerance genes recently cloned in sorghum and wheat. 3) An investigation of the role of hyperexpression of a suite of micronutrient and heavy metal-related genes in heavy metal hyperaccumulation in Thlaspi caerulescens will involve investigation of cis and trans factors that control micronutrient (Zn) homeostasis in the related non-accumulator, Arabidopsis thaliana, and how these elements are altered in T. caerulescens to contribute to the enhanced metal accumulation and tolerance. 4) We have recently identified several genes that play important roles in the hyperaccumulation phenotype in T. caerulescens, including a heavy metal ATPase and a protein kinase, and the functioning of these genes in heavy metal hyperaccumulation, as well as in micronutrient nutrition will be studied.