Diversity, spatial variation, and temporal dynamics of virulences in the German leaf rust (Puccinia recondita f. sp. secalis) population in winter rye

Abstract

A large collection of German rye leaf rust isolates was analysed to characterize the diversity, spatial variation and temporal dynamics of virulences. Virulence-avirulence phenotypes (=pathotypes) were determined on 23 host differentials. We found 93 pathotypes among 177 single-uredinial isolates in 2000, 201 pathotypes among 437 isolates in 2001, and 125 pathotypes among 213 isolates in 2002. In total, the 827 analyzed isolates represented 317 pathotypes. Frequency of virulences on the individual differentials varied from 2% to 97%. Eight of the differentials showed a high resistance level with virulence frequencies <10%. Virulence complexity of the isolates ranged from 3 to 21 with a mean of nine. The percentages of highly virulent isolates (>14 virulences) increased from 4 to 15% during the sampling period. A high level of virulence diversity was observed within and between individual sampling sites with Simpson indices around 0.9. Evenness indices ranged from 0.88 to 0.92. Four of the five most frequent pathotypes were found in each year but their frequency never exceeded 10%. Isolates with unusual virulence combinations could be clearly separated by principal component analysis. Locationspecific pathotype frequencies were revealed in each year, but the frequency patterns varied across years. On four fields a considerable increase of highly virulent pathotypes occurred within 6 weeks during the epidemic. The high diversity of pathotypes as well as the fast accumulation of highly virulent Eur J Plant Pathol (2012) 132:23-35 pathotypes favour the adaptation of the pathogen to race-specific host resistances. More durable resistance might be achievable by combining new effective racespecific resistances with adult-plant and/or race-nonspecific quantitative resistances.

Assessing new SSR markers for utility and informativeness in genetic studies of brown rust fungi on wheat, triticale, and rye

“…The collection of isolates of Pt and Prs from Poland revealed remarkable differences in virulence to wheat, triticale, and rye, which was contributed mainly by host species specificity among isolates tested, that is, Pt isolates were virulent only to wheat and triticale, whereas Prs isolates could infect only rye, confirming species characteristics (Anikster et al, 1997). Based on the virulence of 15 Prs isolates on eight rye differential lines, we identified seven different pathotypes, proportionally similar to 317 pathotypes observed among 827 Prs isolates collected over 3 years from different sites in Germany (Miedaner et al, 2012). However, very low variation of virulence phenotypes was observed within the Prs collection (KW = 0.03), which could be due to the small numbers of both isolates and differential lines available.…”

Survival of Fusarium graminearum, the causal agent of Fusarium head blight. A review

“…In July, F. equiseti and F. culmorum were isolated in addition to F. graminearum and F. sporotrichioides, while in August, all species were isolated. Although weed removal has been an important part in the control of different fungal plant diseases for many decades (Mantle et al 1977;Miedaner et al 2011), it is clear that the reduction soil tillage and sustainable pesticide use are clearly going to bring about with them a new focus on the role of weeds in Fusarium head blight mediation (Landschoot et al 2011;Postic et al 2012).…”

Identification of Single Nucleotide Polymorphisms Associated with Brown Rust Resistance, α-Amylase Activity and Pre-harvest Sprouting in Rye (Secale cereale L.)

“…Three additional genes, Pr3 , Pr4 , Pr5 , associated with race-specific resistance to brown rust, were identified by Roux et al ( 2004 ). Specific resistance is an effective strategy, often used in breeding, against P. recondita as well as other biotrophic pathogens, but unfortunately its durability is not satisfactory (Miedaner et al 2012 ). An alternate approach focuses on nonspecific resistance.…”