Identification of suitable fertility restorer lines for development of hybrid rice (Oryza sativa L.)

One of the main priorities of using heterosis for development of hybrid rice is to identify the suitable fertility restorer lines. Therefore, to identify suitable fertility restorer lines and evaluate rice hybrids, 36 F1 hybrids developed from crossing of two cytoplasmic male sterile lines, JelodarA and NedaA, together with 13 lines from local cultivars and four foreign fertility restorer lines as paternal lines as well as JelodarA and NedaA, as second crop, using randomized complete block design in three replications in the research farm of Tabaristan Genetics and Agricultural Biotechnology Research Institute, Sari, Iran, in 2019 and 2020. Mean comparison of morphological traits of F1 hybrids showed that the highest fertility and grain yield belonged to H28, H27, H33, H30 and H29 hybrids, which was mainly due to high fertile tiller number, 1000-grain weight and high panicle fertility. Using SSR molecular markers including RM 171, RM 490 and RM 3148 associated with the fertility restorer genes Rf3 and Rf4 for selection of superior hybrids revealed that RM 3148 marker could identify superior hybrids resulted from crossing of paternal lines IR68078-15-2-1-2-2-R, IR65622-151-1-2-2-2R and IR86403-5-5-2-1-1-1-1-1R with male sterile JelodarA which had similar band as fertility control restorer line and H27, H29 and H33 hybrids. These hybrids had both bands i.e. heterozygous, and based on this marker they carry Rf4rf4 alleles. RM 171 marker also showed the likely presence of Rf4 gene in IR 68078-15-2-1-2-2-R and IR 65622-151-1-2-2-2-R lines and hybrids developed from them. The F1 hybrids had both alleles in heterozygous from Rf4rf4. The results of this experiment showed that IR65622-151-1-2-2-2R was the suitable fertility restorer line for NedaA cytoplasmic male sterile, and IR68078-15-2-1-2-2-R and IR86403-5-5-2-1-1-1-1-1R were suitable fertility restorer lines for JelodarA cytoplasmic male sterile. These fertility restorer lines and cytoplasmic male sterile genotypes can be used in hybrid rice development programs.