DIFFERENTIATION AND CLASSIFICATION OF PARENTAL LINES AND FAVORABLE GENIC INTERACTIONS AFFECTING F1 FERTILITY IN DISTANT CROSSES OF RICE (ORYZA-SATIVA L.)

This study was intended to investigate the extent of genetic different iation in parental lines of rice hybrids and to analyze the genetic ba sis underlying the fertility phenomenon in distant crosses, Two subset s of rice material (111 entries in total) were used, including XI. dou bled-haploid (DM) lines and 30 Indica and Japonica I-ice varieties or lines (as a control). The DH lines was derived from a heterotic Indica /Japonica cross (Gui630/02428) by anther culture. The materials in the control represent a broad spectrum of the Asian cultivated rice gene pool including landraces, primitive cultivars, historically important cultivars: modern elite cultivars, super rice and parents of superior hybrids, In accordance with the NC II design, 57 out of the DH lines w ere test-crossed to two important wide compatibility lines: photoperio d-sensitive genetic male sterile (PGMS) line N422s and thermo-sensitiv e genetic male sterile (TGMS) line Peiai64s. The F(perpendicular to)s and their parents. 182 entries in total, were examined for the perform ance of seven traits in a replicated field trial. All the rice materia ls was surveyed for polymorphisms using 92 RFLP markers selected from two published molecular marker linkage maps. Genotypes of the FI hybri ds at the molecular-marker loci were deduced from the parental genotyp es. The analysis showed that there were two types of genetic different iation in the two subsets of rice material; that is, qualitative diffe rentiation in the control and quantitative differentiation in the DH l ines. In addition, favorable genic interactions (both intra-or inter-l ocus) contributed to better increase the fertility in hybrids of dista nt crosses through incorporation of a wide-compatibility line as the f emale parent. Favorable genic interactions can be applied in hybrid ri ce breeding programs by selecting parents with an appropriate extent o f genetic differentiation.