Mating Types Analysis of Magnaporthe oryzae Populations by Molecular Methods

Soma Samanta,Shubhransu Nayak,Urmila Dhua,L Behera,A K Mukherjee

doi:10.2174/1874070701408010006

Abstract

Rice blast is a devastating disease which is caused by the heterothallic fungus Magnaporthe oryzae. Compatible sexual recombination which occurs between two M. oryzae strains of different mating types, can enhance genetic variability. Assessment of mating type alleles is used as a marker to measure population diversity. Forty six isolates of M. oryzae were collected from infected rice leaves from various ecosystems of coastal Odisha, India, and the mating type analysis using molecular markers was carried out. MAT1-1 mating type was dominating in all the ecosystems and MAT1-2 was found to be present in uplands as well as in irrigated fields. Both mating types could be found in the same field in irrigated ecosystem. The disease spread was very fast vertically as well as horizontally in those fields resulting in blast lesions looking as ‘green islands (gi) produced in senescence leaves’, and MAT1-2 was found to be associated with all gi lesions. Consequently, the management of the disease in those plots was very difficult. Interestingly, ribosomal RNA IGS region could not be amplified in MAT1-2 isolates but consistent amplification was obtained in MAT1-1 mating type isolates.

Highlights

Rice (Oryza sativa L.) supplies approximately 23% of the per capita energy for six billion people worldwide [1]
Couch (anamorph Pyricularia oryzae Cavara; synonym Magnaporthe grisea (Hebert) Barr), is a heterothallic fungus, meaning the population comprises of two distinct mating types (MAT1-1 and MAT1-2) and the sexual reproduction is possible only between the two opposite mating types [5, 6]
809 bp amplicon was obtained corresponding to MAT1-1 locus with about 70% of the isolates Fig. (1)

Summary

Introduction

Rice (Oryza sativa L.) supplies approximately 23% of the per capita energy for six billion people worldwide [1]. Couch (anamorph Pyricularia oryzae Cavara; synonym Magnaporthe grisea (Hebert) Barr), is a heterothallic fungus, meaning the population comprises of two distinct mating types (MAT1-1 and MAT1-2) and the sexual reproduction is possible only between the two opposite mating types [5, 6]. This fungus is considered as highly variable and high degree of pathogenic variation (pathotypes) is observed in the field [8, 9]. Assessment of mating type alleles has been used as a marker to measure population diversity in this pathogen [7, 11]

Methods

Results

Conclusion