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Published on: August 4, 2018
The MAT1 locus is required for microconidia-mediated sexual fertility in the rice blast fungus
Kohtetsu Kita1, Momotaka Uchida1, Tsutomu Arie2
1Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 2788510, Japan.
Abstract:
Rice blast fungus (Pyricularia oryzae) is a heterothallic ascomycete that causes the most destructive disease in cultivated rice worldwide. This fungus reproduces sexually and asexually, and its mating type is determined by the MAT1 locus, MAT1-1 or MAT1-2. Interestingly, most rice-infecting field isolates show a loss of female fertility, but the MAT1 locus is highly conserved in female-sterile isolates. In this study, we performed a functional analysis of MAT1 using the CRISPR/Cas9 system in female- and male-fertile isolates and female-sterile (male-fertile) isolates. Consistent with a previous report, MAT1 was essential for sexual reproduction but not for asexual reproduction. Meanwhile, deletion mutants of MAT1-1-1, MAT1-1-2, and MAT1-1-3 exhibited phenotypes different from those of other previously described isolates, suggesting that the function of MAT1-1 genes and/or their target genes in sexual reproduction differs among strains or isolates. The MAT1 genes, excluding MAT1-2-6, retained their functions even in female-sterile isolates, and deletion mutants lead to loss or reduction of male fertility. Although MAT1 deletion did not affect microconidia (spermatia) production, microconidia derived from the mutants could not induce perithecia formation. These results indicated that MAT1 is required for microconidia-mediated male fertility in addition to female fertility in P. oryzae .
Insights
The MAT1 gene is crucial for sexual reproduction in the rice blast fungus (Pyricularia oryzae). This study reveals MAT1 is essential for both male and female fertility, impacting disease control strategies.
Area of Science:
- Plant Pathology
- Mycology
- Genetics
Background:
- Rice blast fungus (Pyricularia oryzae) causes significant global crop loss.
- Sexual reproduction in P. oryzae is regulated by the MAT1 locus (MAT1-1 or MAT1-2).
- Many field isolates exhibit female sterility despite conserved MAT1 locus.
Purpose of the Study:
- To functionally analyze the role of MAT1 genes in sexual reproduction of P. oryzae.
- To investigate the function of MAT1 in both fertile and sterile isolates.
- To understand the impact of MAT1 deletion on fertility and reproduction.
Main Methods:
- Utilized CRISPR/Cas9 gene editing in P. oryzae isolates.
- Created deletion mutants for various MAT1 genes.
- Assessed phenotypes related to sexual and asexual reproduction, and fertility.
Main Results:
- MAT1 is essential for sexual reproduction but not asexual reproduction.
- Deletion mutants of MAT1-1-1, MAT1-1-2, and MAT1-1-3 showed varied sexual reproduction phenotypes.
- MAT1 genes, except MAT1-2-6, retained function in female-sterile isolates, with deletions impacting male fertility.
- Microconidia from MAT1 mutants failed to induce perithecia formation.
Conclusions:
- MAT1 is indispensable for both female and microconidia-mediated male fertility in P. oryzae.
- Functional differences in MAT1-1 genes may exist among P. oryzae strains.
- Findings provide insights into the genetic control of sexual reproduction for disease management.
