Genetic studies and identification of QTLs for sheath rot disease resistance in rice (Oryza sativa L.)

Abstract

Rice genotypes BPT5204 and HP14, their direct and
reciprocal F1s (DF1&RF1), F2 populations (DF2&RF2) and
recombinant inbred lines (RILs) were evaluated to study
the genetics of field resistance to sheath rot disease (ShR).
Observed frequencies of resistant and susceptible plants
in DF2 and RILs showed 27R:37S ratio and 1R:7S ratio
indicating involvement of three dominant genes with
complementary gene action. Significant differences
between two crosses were observed between DF1&RF1,
and DF2&RF2for panicle exertion and sheath rot attributing
traits indicating the role of cytoplasm in manifestation of
sheath rot resistance. Plants with anthocyanin pigmentation
recorded significantly higher mean for panicle exertion and
higher level of resistance to sheath rot disease in both F2s
and RILs. Single marker analysis indicated association of
anthocyanin with sheath rot resistance making purple
pigmentation as probable morpholigical marker for it.
Composite interval marker analysis revealed qShR-12
located on chromosome-12 and flanked by SSR markers
RM7315 and RM28118 accounting 11.78% of cumulative
phenotypic variation. This is the first report on genetics,
role of cytoplasm, association of anthocyanin pigmentation
and SSR markers with sheath rot disease resistance.