Tissue culture studies in tropical japonica and indica rice Oryza sativa L genotypes with fertility restoration genes

Abstract

The 11 rice genotypes containing five tropical japonica lines and six indica lines were screened for Rf3 and Rf4 fertility restorer genes located on chromosome 1 and 10, respectively. Among the 11 genotypes screened Azucena, Palawan, Iguapecateto, Nira, CB174R and CB87R showed the presence for Rf3 gene and the genotypes Palawan, Azucena, Iguapecateto, Nira, Pato, CB174R and CB87R confirmed their presence for Rf4 gene. The genotypes viz., Nira, CB174R and CB87R had the presence of both Rf3 and Rf4 genes, when screened with gene specific markers DRRM-Rf3-10 (Rf3) and RM6100 (Rf4). newlineThe 11 parents and 13 crosses were studied for their field performance, with focus on fertility related characters. Two crosses viz., Nira×CB87R with a standard heterosis of 9.84 and Iguapecateto×CB174R with a standard heterosis of 2.7, showed positive heterosis, denoting the possibility of exploiting heterotic vigour for spikelet fertility. Overall, the average heterosis for thousand grain weight across all hybrids was positive, indicating that the hybrids had higher thousand grain weight than the parents. newlineTo develop in vitro protocol for plantlet regeneration from mature seeds, five rice genotypes viz., Palawan, Azucena and Iguapecateto of tropical japonica and CB174R and CB87R of indica types, with the objective of identifying suitable media for seed culture. In all the five genotypes, the callus induction frequency was low, when supplemented with newline2,4-D and Kn. Addition of optimum NAA to the media, further increased the callus induction frequency. The highest callus induction frequencies of 83.3%, 86.6% and 81.6% were observed on N6 medium containing 2,4-D 2.5 mg/l, Kn 0.5 mg/l, NAA 1.0 mg/l (PSCIM 6) in Palawan, Azucena and Iguapecateto genotypes. The N6 medium supplemented with 2,4-D 2.0 mg/l, Kn 0.25 mg/l, NAA 0.5 mg/l (PSCIM 3) induced maximum callus induction of 66.7% in CB174R and 71.6% in CB87R.