Cloning and Validation Of Pstol1 Homologs In Maize and Sorghum

Crop performance on tropical soils, many of which are acidic, is the result of adaptation to a multiple stress condition, which consists primarily of tolerance to aluminum toxicity, efficient acquisition of phosphorus (P) that is highly unavailable in those soils, being immobilized in aluminum and iron complexes, and tolerance to drought stress. Pup1 is a major QTL located on rice chromosome 12 that underlies phosphorus deficiency tolerance and has the potential to increase P acquisition efficiency in other cereals. The gene underlying Pup1, designated phosphorus starvation tolerance 1 or PSTOL1, was cloned and found to encode a protein kinase. PSTOL1 overexpression significantly improved grain yield under low-P conditions. In addition, this gene acts as an enhancer or early root growth, facilitating P uptake. Here we will describe ongoing efforts to identify and possibly validate sorghum and maize homologs of rice PSTOL1 as bona-fide genes enhancing P acquisition and thus yield performance in soils where P is highly unavailable. Our strategy comprises bi-parental QTL mapping in maize and association analysis in sorghum, which possibly allows for higher resolution analysis of PSTOL1 homologs. In maize, a PSTOL1 homolog on chromosome 8 was colocalized with a QTL for root traits including volume of fine roots and root length. In sorghum, preliminary data suggests that SNPs within PSTOL1 homologs are associated with different root traits such as root diameter and root length. In addition, our preliminary data suggests that PSTOL1 may have a positive effect on agronomic performance in low-P soils.