Heterogeneity of Powdery Mildew Resistance Revealed in Accessions of the ICARDA Wild Barley Collection

Abstract

The primary genepool of barley comprises two subspecies – wild barley (Hordeum vulgare subsp. spontaneum) and cultivated barley H. vulgare. subsp. vulgare. The former originated 5.5 million years ago in southwest Asia and is the immediate ancestor of cultivated barley, which arose around 10,000 years ago. In this study, the specific resistance of a set of 146 wild barley accessions, maintained by the International Center for Agriculture Research in the Dry Areas (ICARDA), to 32 isolates of barley powdery mildew caused by Blumeria graminis f. sp. hordei was evaluated. The set comprised 146 heterogeneous accessions of a previously tested collection. Seed was obtained by single seed descent and each accession was usually represented by five single plant progenies. In total, 687 plant progenies were tested. There were 211 phenotypes of resistance among the accessions, 87 of which were found in single plants, while 202 plants contained the eight most common phenotypes. The most frequent phenotype was found in 56 plants that were susceptible to all pathogen isolates, whereas the second most frequent phenotype, which occurred in 46 plants, was resistant to all isolates. The broad resistance diversity that was revealed is of practical importance and is an aid to determining the extent and role of resistance in natural ecosystems.

Evaluating barley landraces collected in North Africa and the Middle East for powdery mildew infection at seedling and adult plant stages

“…Progeny of these accessions should be selected according to the resistance trait before further testing. Previous reports showed the mixed reaction of barley landraces against Bgh (Dreiseitl 2017b). In the present research, postulation of resistance genes was feasible for seven landraces (Table 3), whereas possible resistance to Avr Table 2 B. graminis f. sp.…”

“…According to Dreiseitl (2017b) searching for and detecting new resistance is desirable for its utility in breeding programs, for easier identification of minor resistance genes frequently masked by major genes and for improving knowledge of resistance. New resistance genes can be useful by combining them with other known genes or partial Mlo resistance in barley cultivars.…”

A novel resistance against powdery mildew found in winter barley cultivars

“…Most European spring barleys carry the mlo gene of non‐specific resistance (Dreiseitl, ), which is fully effective. For breeding winter barley cultivars, an option is pyramiding genes with minor effect (quantitative resistance) (Niks, Xiaoquan, & Marcel, ) derived from cultivars, landraces (Silvar et al, ) and wild barley (Dreiseitl, ). Such a method has proved effective in breeding the resistance to B .…”

“…Directional selection can lead to differences locally and intercontinentally (Dreiseitl, 2014;Jensen, Dreiseitl, Sadiki, & Schoen, 2013;Komínková, Dreiseitl, Malečková, Doležel, & Valárik, 2016) (Dreiseitl, 2017c), which is fully effective. For breeding winter barley cultivars, an option is pyramiding genes with minor effect (quantitative resistance) (Niks, Xiaoquan, & Marcel, 2015) derived from cultivars, landraces (Silvar et al, 2013) and wild barley (Dreiseitl, 2017b). Such a method has proved effective in breeding the resistance to B. graminis f.sp.…”

“…Many new resistances found through such phenotyping have been detected in cultivars (Dreiseitl, 2011b(Dreiseitl, , 2011c(Dreiseitl, , 2011d(Dreiseitl, , 2018 and more commonly in wild barley, H. vulgare subsp. spontaneum (Dreiseitl, 2017a(Dreiseitl, , 2017b).…”