Tagging of Temperature-Sensitive Genic Male Sterility (TGMS) Gene in Mutant Nemat Cultivar

In rice, the use of male sterility is a prerequisite for the commercial exploitation of heterosis. Two well established male sterility systems in rice are cytoplasmic genetic male sterility (CMS), a three-line system, and environmentally sensitive genic male sterility (EGMS). EGMS has two types of mechanisms: PGMS and TGMS. TGMS lines are sterilized when they are at a temperature above 25-30°C during the cluster and flowering stages. In order to accelerate the development of TGMS lines in various genetic fields, marker-assisted selection (MAS) can increase the speed and accuracy of this transmission. The aim of this study was to identify the chromosomal location of the gene controlling the sterility trait TGMS and the SSR marker associated with this gene in Nemat TGMS cultivar.

 For this study, Nemat TGMS cultivar was crossed with Fajr cultivar to obtain F2 and BC1 populations for genetic studies. After DNA extraction from 142 genotypes and PCR, the results observed in F1, F2 and BCF1 generations clearly indicated that the TGMS trait in TGMS is controlled by a recessive gene. For this study 14 SSR markers were used to determine the marker correlated with TGMS gene. The frequency of recombination between markers and TGMS locus was estimated using maximum likelihood, assuming that all individuals were completely sterile in terms of TGMS homozygous location. Linkage between marker loci and TGMS QTL was tested by chi square (χ2) test and LOD score.

Among the markers, RM110 and RM29 primers had a high correlation with TGMS gene (5.74 and 11.63 cM, respectively). Various markers have been reported by researchers for the TGMS gene on chromosome 2.

The use of mutation in sterilization (TGMS) and variation in cultivar genotype has led to different markers being reported even for a particular gene. The use of markers that have a high correlation with this trait (MAS) can facilitate the transfer of TGMS gene to other cultivars.