Postulation of resistance genes to barley diseases in heterogeneous varieties

Abstract

Resistance to causal agents of diseases is an important varietal characteristic that influences the management practice of crop plants and thus production costs of commodities. At present, almost all European barley varieties possess at least one major gene for resistance to powdery mildew. After hybridizing selected parental varieties, resistance genes often segregate in subsequent generations and, therefore, some varieties comprise lines that differ in the number or combinations of resistance genes. The objective of this research was to describe the various methods available for postulating resistance genes to pathogens in heterogeneous varieties using resistance to powdery mildew of barley as an example. Four spring barleys ('Orbit', 'Malva', 'Tocada' and CLE 233), and a six-row variety of winter barley, F 12872, were screened. For postulating resistance genes, several testing procedures and many Blumeria graminis f.sp. hordei isolates were used. Minimum amounts of seed were determined and different methods of obtaining homogeneous seed samples from heterogeneous varieties were compared. It was found that 'Orbit' and 'Malva' are composed of three and 'Tocada', CLE 233 and F 12872 of two lines with different resistances to powdery mildew. Problems of postulating resistance genes in heterogeneous varieties and the advantages of testing leaf segments instead of young plants are discussed.

Powdery mildew resistance genes in barley varieties grown in Australia

“…However, heterogeneity is also often caused by mechanical admixtures with other varieties. To postulate resistance genes in heterogeneous varieties, homogeneous component lines or a specific method of testing are usually required (Dreiseitl 2011f). If the number of homogeneous samples tested is low, the probability of detecting all lines constituting the given variety decreases.…”

Susceptibility of spring barley varieties to fungal diseases and their economic value under chemical control

“…Norėdami pagerinti augalų produktyvumą ir produkcijos kokybę, selekcininkai kuria veisles, kurios yra vis atsparesnės ligoms ar kenkėjams (Sleper, Poehlman, 2006). Atsparumas ligų sukė lėjams yra reikšminga veislės savybė, turinti įtakos pasėlių auginimo ir priežiūros praktikai, produk cijos gamybos sąnaudoms ir yra svarbi daugelio žemės ūkio sistemų augalų apsaugos programų dalis (Dreiseitl, 2011). Veislių ūkinis vertingumas gali skirtis: kai kurios veislės tiek įprastomis, tiek ekologiškomis auginimo sąlygomis gali duoti gana gerą ir stabilų derlių (Kokare et al, 2014).…”