Effects of alien cytoplasm substitution on the response of wheat cultivars to Septoria nodorum

Abstract

SUMMARYThe effects of alien cytoplasm substitution on the response of wheat to Septoria nodorum were studied, using alloplasmic series of two cultivars, Chris and Selkirk. In general, cytoplasmic substitution caused unidirectional effects on Septoria‐response, alloplasmic lines of both cultivars expressing lower levels of partial resistance (in leaf and head tissue) but higher levels of yield tolerance than the corresponding euplasmic line. The reduced resistance in alloplasmics was closely associated with reduced incubation periods of Septoria infection in both leaf and head tissue. Cytoplasmic substitution resulted in increased yield tolerance to Septoria‐infection in both the non‐tolerant Selkirk and the relatively tolerant Chris. Unlike their effects on partial resistance, specific cytoplasms exerted similar effects on tolerance in the two parental cultivars, several cytoplasms of the D plasmatype being particularly effective in increasing Septoria‐tolevance. The potential for the development of Septoria‐toterant cultivars by the incorporation of alien cytoplasms is discussed, in view of the observed neutral effects of D plasmatype cytoplasms on other agronomic traits.