Resistance of wild emmer wheat to stem rust: Ecological, pathological and allozyme associations

Abstract

Seedling resistance to wheat stem rust was determined in populations of wild emmer wheat, Triticum dicoccoides, and characterized by means of ecological factors and allozyme genotypes . Reactions to wheat stem rust were studied in 102 single plant accessions of T. dicoccoides from ten populations by inoculation with Puccinia graminis tritici race 14, isolate GSR-739 . Six populations displayed different degrees of response polymorphism with reactions ranging from high resistance to complete susceptibility, whereas four populations contained only susceptible plants . In some of the accessions, unexplained intrasib variation in resistance and intraplant variation of infection-types were found . Resistance to stem rust was negatively correlated with two ecological factors, altitude and number of 'Sharav' (hot-dry) days which are unfavorable to disease development . Variation in stem rust response was shown to exist in ecogeographic regions where climatic variables enhanced the development of the fungus, conceivably maintained by natural selection . Likewise, allozyme genotypes, single or in multiple loci combinations, appeared to be associated with resistance or susceptibility to rust . Such association need to be verified by genetic studies in order to become established as useful markers .

Genotype, environment, and genotype by environment interactions determine quantitative resistance to leaf rust (Coleosporium asterum) in Euthamia graminifolia (Asteraceae)

“…Much of the observed annual variation in overall infection intensity may be the result of stringent weather conditions necessary for growth of the fungal population. Nevo et al (1991) found that significant rust infection of wheat requires a minimum number of degree days with high humidity. These conditions were guaranteed for our potted plant surveys, both of which had high overall infection intensity, because regular watering kept their foliage damp.…”

Molecular Genetic Maps in Wild Emmer Wheat, Triticum dicoccoides: Genome-Wide Coverage, Massive Negative Interference, and Putative Quasi-Linkage

“…Wild emmer wheat is an important genetic resource that could be exploited in breeding for resistance to a broad range of diseases, pests, and for tolerance to poor soil and climatic factors (Nevo 1983(Nevo , 1989(Nevo , 1995. Among many agriculturally important characteristics already found in T. dicoccoides is its resistance to stripe rust (Gerechter-Amitai and Stubbs 1970;Nevo et al 1986;Fahima et al 1998), stem rust (Nevo et al 1991), and powdery mildew (Nevo et al 1985). Wild emmer wheat contains rich and variable genetic resources that will play a major role in future wheat improvement (Nevo 1983(Nevo ,1989(Nevo , 1995.…”

Responses of Israeli wild emmers to selected Australian pathotypes of Puccinia species

“…(1) central (2) xeric marginal (# 16-23) and (3) mesic marginal (# 24-33) . The xeric locations were further subdivided into xeric warm marginal, eastern and southern on the basis of meteorological records (see Nevo & Beiles, 1989 ;Nevo et al ., 1991) .…”