Inheritance of sterility mosaic disease resistance to Bangalore and Patancheru isolates in pigeonpea (Cajanus cajan (L.) Millsp.)

Sterility mosaic disease (SMD), is an important biotic constraint in pigeonpea (Cajanus cajan (L.) Millsp.) in Indian subcontinent. It is caused by a virus and transmitted by eriophyid mites, Aceria cajani Channabasavanna. A comprehensive study of variability in the sterility mosaic pathogen revealed the occurrence of five different isolates in India. Amongst them, three distinct isolates have been characterised, viz., Bangalore, Patancheru and Coimbatore. Studies were conducted at Bangalore and Patancheru to determine the inheritance of resistance to Bangalore and Patancheru isolates of the SMD involving a resistant (ICP 7035) and susceptible (TTB 7) genotypes. Observations in parents, F₁ indicated dominance of susceptibility over resistance. The disease reaction of the individual F₂ plant derived F₃ families for Patancheru isolate was controlled by two genes with dominance epistasis and for Bangalore isolate, absence of resistant plants indicate action of two or more genes in controlling resistance to SMD.