Morphological and molecular characterization of Neopestalotiopsis vitis associated with leaf blight disease of Manilkara zapota-a new record from India.

Abstract

Sapota is an important horticultural crop grown in India, and Karnataka is a major producer of sapota. A characteristic leaf blight disease was observed in Southern Karnataka during field surveys conducted in 2019 with an incidence of 13-22% in approximately 45ha of sapota field. The leaf blight-associated pathogen was isolated on the potato dextrose agar medium. A total of 12 isolates obtained from each location were identified culturally and morphologically. Based on the morphological and cultural features, the pathogen was identified as Pestalotiopsis or Neopestalotiopsis, which was further confirmed by molecular identification using a representative isolate (MZ03). The ITS rDNA and β-tubulin genes were amplified and sequenced using ITS1/ITS4 and T1/T22 primer pairs respectively. nBLAST search analysis and concatenated (ITS-rDNA and TUB2 loci) phylogenetic analysis confirmed the pathogen identity as Neopestalotiopsis vitis. Pathogenicity tests conducted on detached leaves by inoculation with a conidial suspension of N. vitis produced typical blight symptoms after 4-5days and progressed to cover the entire leaf lamina after 10-12days. The pathogen's identity was confirmed after re-isolation by cultural and morphological features. Although Pestalotiopsis clavispora and Pestalotiopsis versicolor causing diseases on sapota seedlings and trees have been reported, no reports are available for the occurrence of N. vitis to sapota from India. This is the first report of N. vitis associated with leaf blight disease of sapota from India.