Global incidence of wheat rusts and powdery mildew during 1969–2010 and durability of resistance of winter wheat variety Bezostaya 1

Abstract

Disease incidence and severity was studied for winter wheat variety Bezostaya 1 and susceptible checks based on data from international nurseries from 1969 to 2010 and from 51 countries across major winter wheat production regions totalling 1,047 reports. The frequency of leaf rust and stripe rust occurrence was stable over time with marked increases in severity in 2001-2010 especially in Europe and Central and West Asia. Substantial global reductions in stem rust occurrence were recorded and attributed primarily to use of resistance genes although the recent emergence of race Ug99 makes wheat more vulnerable. The occurrence of powdery mildew remained globally stable over time. It was the most important foliar disease in Western and Southern Europe, where the frequency was very high for all time periods coupled with slight increases in severity during 2001-2010. The durable resistance of variety Bezostaya 1 to all four diseases was demonstrated in the study using comparisons of disease severities of Bezostaya 1 and the most susceptible entries. The Lr34/Yr18/Pm38 pleiotrophic set possessed by Bezostaya 1 is currently an important target for selection because it is now amenable to molecular selection. Increased use of genes like Lr34 combined with strategies to minimize Eur J Plant Pathol (2012) 132:323-340

In Turkish wheat cultivars the resistance allele of LR34 is ineffective against leaf rust

“…Increased infection rates were also reported for stripe rust during the same time periods (Morgounov et al 2012). The severity of this rust species increased from 14% in 1969-1981 to 17% in 1988-2000 and 26% in 2001-2010.…”

“…Contrary to leaf and stripe rust, Morgounov et al (2012) observed a reduction of 38% in the occurrence of stem rust from 1969 to 1981, and of 7% from 2001 to 2010. Despite this decrease in disease incidence, in Bezostaya 1 disease severity increased from 28% in 1969-1981 to 42% in 2001-2010.…”

“…Interestingly, incidences of powdery mildew remained stable during 42 years. Apparently, resistance of Bezostaya 1 to this disease remained at sufficient levels (Morgounov et al 2012).…”

“…Morgounov et al (2012) indicated an erosion of this resistance during the last 40 years in Turkey. In that study, the response of Bezostaya 1 and of the most susceptible cultivars were compared based on the data collected in 51 countries from 1969 to 2010.…”

Localization of the powdery mildew resistance gene Pm07J126 in wheat (Triticum aestivum L.)

“…Powdery mildew (Pm), caused by Blumeria graminis f. sp. tritici (Bgt), is a severe and globally significant disease of common wheat, with an occurrence of about 54 % in crops worldwide during 2001-2010(Morgounov et al 2012. Yield losses caused by the disease range from 13 to 34 %, but if the disease is severe losses can exceed 50 % (Griffey et al 1993).…”