Genetic analysis of environment-sensitive genic male sterile rice under US environments

Abstract

Two line hybrid rice (Oryza sativa L.) breeding uses environment-sensitive genic male sterile (EGMS) lines to produce sterile or fertile pollen depending on daylength and/or temperature. There is limited information on the performance and genetic control of EGMS lines under U.S. environments. Therefore, genetic characterization of two F2 and four BC1F2 populations derived from EGMS line 2009S was conducted under Louisiana field conditions. Chi squared analyses in the F2 and BC1F2 populations indicated that pollen sterility under high temperature and long daylength field conditions was controlled by a single recessive gene. Sequence comparisons at locus LOC_Os02g12290 between 2009S, CL161 (USDA-AMS 2002) and published sequences of G63S and Nipponbare revealed a single nucleotide polymorphism (SNP) that has been detected previously in several EGMS lines. Due to high GC content, a CEL1 nuclease assay was used to detect SNPs associated with pollen sterility in 177 F2 and 59 BC1F2 sampled individuals. A high percentage of lines (90–100%) across all segregating populations were identified correctly as pollen sterile using the CEL 1 assay. Results from this study suggest that single-gene control of pollen sterility in EGMS line 2009S will be compatible with a two-line system for U.S. hybrid rice development.