Development of Quantitative Real-Time PCR Assays to Quantify Erysiphe pisi and Erysiphe trifolii and Its Implementation for Monitoring Their Relative Prevalence in Pea Crops in Spain and Tunisia

Abstract

E. pisi was thought to be the only causal agent of powdery mildew in peas, with three genes, er1, er2 and Er3, conferring resistance to this pathogen. Recently, E. trifolii has also been found to cause this disease in peas in different countries, but its relevance in pea powdery mildew disease worldwide is unknown. The objective of this study was to develop a method to identify and quantify E. pisi and E. trifolii and use it to analyze the relative prevalence of E. pisi and E. trifolii in pea fields in Spain and Tunisia. We also wanted to discern the effect of the er1, er2 and Er3 resistance genes on the relative amount of E. pisi/E. trifolii. Using the polymorphic sites present between E. pisi and E. trifolii ITS sequences, we developed a qPCR method capable of identifying and quantifying these pathogens. Our results revealed, for the first time, the occurrence of E. trifolii in Tunisia and that the presence of er1, er2 and Er3 genes have a clear effect on the ratio E. pisi/E. trifolii in both countries.

Elucidating the Response of Diverse Faba Bean Genotypes to Powdery Mildew Infection

“…It has also been reported that E. trifolii causes powdery mildew in peas and Lathyrus spp. It is severe only in late-planted nurseries in Cordoba and, normally, in India with higher temperatures during the crop season [24,[32][33][34][35]. This is also what we found on faba beans, with infection only occurring in late-planted nurseries.…”

Breeding for Biotic Stress Resistance in Pea

“…To date, 12 er1 alleles have been identified, including two artificial chemical mutations (er1-5 and er1-10) and ten natural mutations [30]. However, E. trifolii is known to defeat er1 resistance, requiring breeding attention [31,32]. Therefore, pyramiding more than one gene into a single background is desirable.…”

Genetic Diversity Analysis based on the Virulence, Physiology and Regional Variability in Different Isolates of Powdery Mildew in Pea

“…or Erysiphe baeumleri U. Braun and S. Takam., in addition to E. pisi , may affect peas in specific environments [ 3 , 9 ]. However, the symptoms of powdery mildew caused by these pathogenic species are almost too similar to distinguish between them.…”