Macroscopic and Histological Characterisation of Genes er1 and er2 for Powdery Mildew Resistance in Pea

Abstract

Fondevilla, S., Carver, T. L. W., Moreno, M. T., Rubiales, D. (2006). Macroscopic and histological characterisation of genes er1 and er2 for powdery mildew resistance in pea. European Journal of Plant Pathology, 115, (3), 309-321 Keywords: grain legumes - haustorium - histology - hypersensitive resistanceIn pea, two single recessive genes, er1 and er2, have been identified for resistance to powdery mildew caused by Erysiphe pisi, but little is known about their mode of action. Pea accessions carrying the genes er1 or er2 and other accessions displaying resistance to powdery mildew in the field were studied. In accessions carrying gene er1, epidermal cell penetration was prevented and very few haustoria or colonies were formed. Under controlled conditions, er1 conferred complete or almost complete resistance to the fungal isolates used and this resistance was not associated with macroscopically visible necrosis. Under field conditions these accessions developed a low level of disease. Resistance in line JI2480 (carrying er2) increased with temperature and leaf age, and complete resistance was expressed only at high temperature (25 ?C) or in mature leaves. This resistance was based mainly on post-penetration cell death, complemented by a reduction of percentage penetration success in mature leaves. Combining the resistance provided by gene er1 and by line JI2480 into new cultivars is likely to increase their level of resistance and enhance durability of the protection.Peer reviewe

Identification of a New Gene for Resistance to Powdery Mildew in Pisum fulvum, a Wild Relative of Pea

“…Incubation was initiated under a 6 h light period (250 µmol m −2 sec −1 ), followed by cycles of 12 h darkness/12 h light. This detached leaf method was selected because it had been previously effective for the evaluation of the response to E. pisi in pea (Fondevilla et al 2006(Fondevilla et al , 2007 and had enabled the inoculation of only one leaf of the plant, keeping the rest of the plant free from the disease.…”

“…1. Procedure used to obtain a population segregating for resistance to E. pisi resistance conferred by er2 was only expressed at a high temperature (25°C), whereas the expression of Er3 was independent of the temperature (Fondevilla et al 2006(Fondevilla et al , 2007. However, previous attempts to cross the line P660-4 with pea lines carrying the genes er1 and er2 resulted in rather sterile F 1 plants.…”

Two powdery mildew resistance mutations induced by ENU in Pisum sativum L. affect the locus er1

“…Natural sources of resistance to powdery mildew in pea have been identified in germplasm from all continents, and regardless of their origins all sources of resistance to this disease have shown monogenic recessive inheritance (Harland 1948;Liu et al 2003;Sharma 2003;Fondevilla et al 2006). Moreover, one single locus-referred to as er1 by Heringa et al (1969)-seems to be responsible for most of the powdery mildew resistances (PMR) identified so far (Sharma 2003).…”

“…This monogenic recessive resistance was shown to be partially or totally broken depending on biotic and abiotic stress factors such as (leaf) age, field versus glasshouse/growth cabinet growing conditions (Heringa et al 1969;Tiwari et al 1997;Fondevilla et al 2006) and temperature (Heringa et al 1969;Fondevilla et al 2006).…”

Herança da resistência a oídio em ervilha e aspectos relacionados à patogênese

“…O gene er2 tem provado ser menos duradouro, promovendo somente uma resistência foliar, podendo esta ser superada com uma elevada pressão de inóculo ou de acordo o ambiente de cultivo (TIWARI et al, 1997a;HERINGA et al, 1969). Essa instabilidade é devido a influência da temperatura e idade da folha na expressão do gene (FONDEVILLA et al, 2006). Ambos os genes são herdados independentemente e a combinação destes em uma cultivar, pode aumentar a durabilidade dessa resistência (TIWARI et al, 1997b).…”