# Analysis of the Mating-Type Distribution and Fertility Variation in Magnaporthe oryzae Populations in China

## TL;DR

This study examines the mating-type distribution and fertility of a rice pathogen in China, finding imbalances and low fertility linked to climate and asexual reproduction.

## Contribution

The study reveals mating-type imbalances and fertility deficiencies in M. oryzae populations across China, linked to temperature and asexual reproduction.

## Key findings

- MAT1-2 mating type dominated (79.21%) over MAT1-1 (20.79%) in M. oryzae isolates.
- Mating-type distribution correlated with effective accumulated temperature (≥10 °C).
- MAT1-2 isolates showed significantly higher fertility than MAT1-1 isolates.

## Abstract

Magnaporthe oryzae exhibits significant genetic polymorphism in paddy fields. This study collected and isolated 832 single-spore isolates from major rice-producing areas of 17 provinces in six geographical regions across China, analyzing their mating-type distribution, fertility variation, and underlying mechanisms. Polymerase chain reaction (PCR) assays revealed a significantly higher proportion of the MAT1-2 mating type (79.21%) than MAT1-1 (20.79%), with severely skewed ratios in some regions. Correlation analysis indicated that mating-type distribution was significantly associated with effective accumulated temperature (≥10 °C). MAT1-1 was predominantly concentrated in regions with 4500–7000 degree-days, whereas MAT1-2 was mainly found in regions with 2500–5000 degree-days. Cross-culture fertility tests yielded an average fertility rate of 36.54% and mean perithecia production of 25.7 per isolate, suggesting generally low fertility, with MAT1-2 isolates showing significantly higher fertility than MAT1-1. This study demonstrates that regional M. oryzae populations in China exhibit both mating-type imbalances and fertility deficiency, suggesting rare genetic recombination in natural populations and evolution primarily driven by asexual reproduction.