Germplasm Evaluation Of Low-Phosphorus Tolerance In Maize And The Genetic Dissection Of Its Genetic Basis

Low-phosphorus (LP) stress in maize is a global problem and has been exacerbated by breeding activities that have reduced the genetic diversity of maize. Developing LP-tolerant maize varieties may thus require the introduction of exotic germplasm into modern maize accessions. Meanwhile, it is important to dissect the genetic basis of LP tolerance of maize, which would be helpful for molecular breeding of LP-tolerant maize varieties. In this research, large-scale germplasm evaluation was performed for LP tolerance in maize, and the genetic basis of LP tolerance was also dissected, the main results are as follows:1.826maize accessions (including580tropical/subtropical accessions and246temperate accessions) were evaluated for LP tolerance under both LP and normal-phosphorus conditions in2011and2012. LP-tolerant and sensitive accessions were selected based the relative trait values of all traits using principal component analysis, and all the14traits of the tolerant maize accessions showed less reduction than the sensitive accessions under LP conditions, supporting the reliability of our selection.2. Selection was also performed based on LP tolerance and P response, which would help to select accessions tolerant to LP stress, and accessions that had better performance under both P conditions. The selected lines would not only be useful for dissecting the genetic mechanism of LP tolerance, but also could be used as donors for LP tolerance improvement.3. Nine tolerant and eight sensitive accessions were identified and re-sequenced. By comparing26million SNPs between tolerant and sensitive lines, we identified16250SNPs that were specific in at least eight tolerant lines or seven sensitive lines, with121SNP hotspots identified when the false discovery rate was set at0.10. The hotspot regions contained37genes homologous to those previously identified to be involved in plant LP tolerance.