Isolation and identification of Cladosporium tenuissimum causing leaf blight on garden pea (Pisum sativum L.) in Telangana from southern India

Abstract

Garden pea (Pisum sativum L.), is an important legume grown worldwide as a source of proteins and carbohydrates. Since pea crop is cultivated globally in cool temperate climatic conditions, increasing temperatures accompanied by high humidity favors fungal infections. A fungal infection causing leaf blight symptoms was frequently observed on the leaves of pea plants grown in greenhouse and field conditions. The blight symptoms showed a water-soaked and wilting appearance with curly leaf edges accompanied by greyish mycelial growth and chlorotic lesions. The disease incidence in field conditions ranged between 5 and 10 %, whereas in the controlled greenhouse conditions, it ranged from 40 to 45%. Two isolates of the fungus, Gp03 and Gp04 were isolated from Arkel pea leaves and purified from a single conidium each. According to Koch's postulates, the pathogenicity tests with these isolates using detached leaf assay and whole plant leaf assays confirmed the pathogen. Morphological and molecular analysis of nucleotide sequences of the D1-D2 region, translation elongation factor-1α (TEF) and actin (ACT) genes confirmed these isolates as members of the genus, Cladosporium. The phylogenetic relatedness of these isolates with other members of the Cladosporium genus revealed them as fungal strains of Cladosporium tenuissimum. Further, these isolates were also confirmed as C. tenuissimum by Microbial Type Culture Collection and Gene Bank (MTCC), Chandigarh in India, and provided the accession nos. MTCC 13581 and MTCC 13582 to the C. tenuissimum strains, Gp03 and Gp04 respectively. This is the first report of Cladosporium tenuissimum infecting garden pea in Telangana, India.