RAPD analysis of Fusarium Isolates Causing “Mango Malformation” Disease in Pakistan

Abstract

Mango Malformation (MM) disease is a major constraint to mango production. A total of 20 Fusarium isolates from MM-affected mango plants were collected from 14 locations in Pakistan and assessed for genetic diversity using the random amplified polymorphic DNA (RAPD) technique. A total of 393 fragments were amplified after screening with 50 random primers. The amplifications with 45 primers identified scoreable polymorphisms among the isolates. A genetic similarity matrix based on Nei and Li’s index determined coefficients ranging from 46.46% to 92.51%. These coefficients were used to construct a dendrogram using the UPGMA algorithm. The isolates grouped into two main clusters, comprising 13 and 7 isolates respectively, at a genetic relatedness of 52%. Within the clusters, Fusarium isolates were not necessarily related either by geographic origin or by the mango cultivar from which they were isolated. RAPD proved a reproducible and tractable means of differentiating Fusarium isolates. These findings also suggest that some infections originate not from adjacent plants within an orchard but from geographically distant areas; indicating that most probably infection occurs in nurseries prior to plants being transported around the country for subsequent cultivation, and that improved plant hygiene could significantly curb MM infection and spread.