Identification of sources of resistance against Aphanomyces root rot in a Pisum germplasm

Root rot caused by the oomycete Aphanomyces euteiches Drechs. is one of the most important diseases affecting to pea production around the world. Breeding for resistance is one of the main effective and environmentally friendly means to control the disease. The aim of this study was to identify new sources of resistance to A. euteiches in a Pisum spp. germplam collection. To this purpose, 324 pea accessions including comercial and wild genotypes were exposed to A. euteiches under controlled conditions. Six seeds of each genotype were sown in 200 ml plastic pots containing a mix of sand and peat (1:1). After 10 days, plants were inoculated applying 5 ml of a zoospores solutions of 103 spores/ml. Once per four days, disease symptoms were evaluated using a scale from 0 (healthy plant) to 5 (dead plant) for 20 days. The related area under the disease progression curve (AUDPC) was also calculated according to the level of symptoms. The results of this screening revealed a large variability in the response of specific pea accessions ranging from highly resistant to susceptible within the collection. Twenty genotypes including P. sativum, P. sativum spp. elatius and P. fulvum showed a potential resistence to Aphanomyces root rot (level of symptoms ≤ 2). This study provides important information for future peas breeding programs based on the resistance of wild genotypes.