Sexual reproduction and soil tillage effects on virulence of Pyrenophora teres in Finland

Abstract

Knowledge of the virulence of a pathogen population and recognition of the risks of changes in the virulence spectrum are essential in breeding crops for disease resistance. Sexual recombination in a pathogen increases the level of genotypic diversity and can influence the virulence spectrum. This study aimed to determine how sexual recombination can change virulence of the barley pathogen Pyrenophora teres and whether the barley cultivation system, no-tillage or normal tillage, influences P. teres virulence. The inheritance of avirulence/virulence in P. teres following sexual reproduction was studied in three artificially created pathogen populations. The first was a product of crossing two net forms of the pathogen, and the second and the third were products of crossing net and spot forms. None of the progeny generated resembled the parents exactly. The average similarity of the progeny isolates of the net by net cross with the parental type, based on avirulence/virulence tests, was 92%. That for net and spot form progenies was 58% in comparison with the net form parents and 73% with the spot form parents. The virulence reactions of the progeny isolates did not correlate with morphological traits of the isolates: growth rate on agar, spore production, spore width, spore length and numbers of septa per conidium. To study the effect of the barley cultivation method on P. teres virulence, 313 single-spore cultures were obtained from barley fields. Two hundred and seventy-six of the isolates represented the spot form and 37 represented the net form of P. teres. No association was established between the tillage method and virulence for either the net form or the spot form isolates.

Predictive Association between Biotic Stress Traits and Eco‐Geographic Data for Wheat and Barley Landraces

“…New epidemics of the net blotch recently have been reported around the world (McLean et al, 2009; Liu and Friesen, 2010). Development of resistant varieties is the most cost‐efficient method for control of net blotch (Jalli, 2010a, b). Silvar et al (2010) reported finding few examples of resistance to net blotch in the Spanish barley core collection.…”

Transposable Element Genomic Fissuring in Pyrenophora teres Is Associated With Genome Expansion and Dynamics of Host–Pathogen Genetic Interactions

“…PTM appears to have spread since, being noted in Australia in 1977 ( Khan and Tekauz, 1982 ) and in Montana, United States in 1981 ( Bockelman et al, 1983 ). Although artificial hybrids can be readily made in the laboratory ( McDonald, 1967 ; Smedegård-Petersen, 1977a ; Campbell and Crous, 2003 ; Jalli, 2011 ), PTT and PTM are considered to be genetically autonomous populations ( Rau et al, 2003 , 2007 ; Bakonyi and Justesen, 2007 ; Bogacki et al, 2010 ; Lehmensiek et al, 2010 ; Leišová-Svobodová et al, 2014 ; Akhavan et al, 2016 ). Natural hybrids appear to be rare and have been suggested by RAPD and AFLP studies ( Campbell et al, 2002 ; Leišova et al, 2005 ; McLean et al, 2014 ), and recently confirmed by Poudel et al (2017) using form-specific markers.…”

“…However, a lack of field hybrids suggests a natural barrier to fertility as found by Smedegård-Petersen (1977a) or a fitness penalty. The significance of such field hybrids is they may potentially increase population genetic diversity, resistance to fungicides and form new virulence combinations ( Campbell et al, 1999 ; Jalli, 2011 ) although their contribution in these respects is unknown.…”

Effects of climate and historical adaptation measures on barley yield trends in Finland

“…Fungicide usage in Finland re mains low compared to other European countries (Heinonen et al 2013). However, a significant im provement in the level of net blotch resistance has been found in the European barley cultivars released during the last 40 yr (Jalli 2011). Net blotch is the most common plant disease found in barley in Finland.…”