Pathogenic and molecular characterization of Fusarium moniliforme Sheld, the incitant of Fusarium maize stalk rot in the Punjab State of India

Abstract

Fifty six isolates of Fusarium moniliforme collected from different maize cultivars grown in various regions of Pun- jab were characterized for their pathogenic variation and molecular diversity. Based on the multivariate cluster analysis of pathogenicity data, seven clusters were formed, each representing a specific disease reaction to a par- ticular maize hybrid/inbred line used in this study. The isolate Fm 10 was found the most virulent with an average disease index (ADI) of 66.6% whereas, Fm 45 was found least virulent with ADI of 42.5%. The sub-mountaneous undulating region of Punjab represented maximum percentile of least virulent isolates, however, undulating plain region of Hoshiarpur and Shaheed Bhagat Singh Nagar district of the State represented the most virulent zone of F. moniliforme isolates. Genetic diversity in the Punjab populations of F. moniliforme was studied using twenty random amplified polymorphic DNA (RAPD) markers, out of which 18 showed amplification with a total of 220 amplified fragments. Primer OPT-12 was found to be highly polymorphic with PIC value of 0.913 while OPT-9 was least polymorphic. The size of amplified DNA fragments ranged from 0.1-2.0 kb. Dendrogram based on molecular data generated by 18 RAPD primers showed six clusters with similarity percentage ranging from 36 to 96% and one independent lineage with 26% similarity coefficient. No correlation was obtained between the genetic diversity and pathogenic variation; however the latter was influenced by agro-climatic zones of north-western India. This was the first attempt to study the genetic diversity of F. moniliforme causing Fusarium stalk rot of maize in Punjab.