Molecular Identification and Variability of Pestalotiopsis Microspora of Coconut by RAPD Marker

Abstract

Coconut (Cocos nucifera L.) is one of the most important fruit trees in Bangladesh. This tree is susceptible to various pathogens. The present study was conducted to determine the molecular identification and genetic variability of Pestalotiopsis microspora, the causal organism of coconut leaf spot disease.An experiment was conducted with thirteen Pestalotiopsis microspora isolates during the period from January 2021 to January 2022 in the Plant Protection Laboratory of Agrotechnology Discipline, Khulna University, Khulna. The isolates were obtained from infected coconut leaves collected from different locations of Khulna Division. Among the thirteen isolates, three isolates (Pm2, Pm5, and Pm11) were randomly selected for molecular identification. The ITS region of the pathogenic fungi was sequenced, and the tested isolates were identified as Pestalotiopsis microspora. The isolated fungi showed 100% similarity with Pestalotiopsis microspora sequences available in GenBank (Accession Nos. OK254035.1, OK254041.1, and AY681483.1). For molecular variability analysis, a total of seven RAPD primers were used, which generated clearly visible banding patterns. Among the thirteen isolates, the highest genetic dissimilarity (88%) was observed between isolates Pm9 and Pm13. These isolates were collected from Koia Bazar, Harintana and Batiaghata, Dumuria under Khulna Division. Cluster analysis grouped the isolates into two major clusters, Cluster I and Cluster II, each of which was further divided into two sub-clusters. Principal Component Analysis (PCA) revealed a positive correlation among isolates Pm1, Pm2, Pm3, Pm5, Pm6, Pm11, Pm12, and Pm13, whereas a negative correlation was observed among isolates Pm4, Pm7, Pm8, Pm9, and Pm10.