A novel epistatic interaction at two loci causing hybrid male sterility in an inter-subspecific cross of rice (Oryza sativa L.)

Takahiko Kubo, Yoshiyuki Yamagata, Maki Eguchi, Atsushi Yoshimura

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42 Citations (Scopus)


Postzygotic reproductive isolation (RI) often arises in inter-subspecific crosses as well as inter-specific crosses of rice {Oryza sativa L.). To further understand the genetic architecture of the postzygotic RI, we analyzed genes causing hybrid ste- rility and hybrid breakdown in a rice inter-subspecific cross. Here we report hybrid male sterility caused by epistatic interaction between two novel genes, S24 and S35, which were identified on rice chromosomes 5 and 1, respectively. Genetic analysis using near-isogenic lines (NILs) carrying IR24 (ssp. indica) seg- ments with Asominori (ssp. japonica) genetic background revealed a complicated aspect of the epistasis. Allelic interaction at the S24 locus in the heterozygous plants caused abortion of male gametes carrying the Asominori allele (S24-as) independent of the S35 genotype. On the other hand, male gametes carrying the Asominori allele at the S35 locus (S35-as) showed abortion only when the IR24 allele at the S24 locus (S24-ir) was concurrently introgressed into the S35 het- erozygous plants, indicating that the sterility phenotype due to S35 was depen- dent on the S24 genotype through negative epistasis between S24-ir and S35-as alleles. Due to the interaction between S24 and S35, self-pollination of the double heterozygous plants produced pollen-sterile progeny carrying the S24-irl S24-ir S35-as/S35-ir genotype in addition to the S24 heterozygous plants. This result suggests that the S35 gene might function as a modifier of S24. This study presents strong evidence for the importance of epistatic interaction as a part of the genetic architecture of hybrid sterility in rice. In addition, it suggests that diverse systems have been developed as postzygotic RI mechanisms within the rice.

Original languageEnglish
Pages (from-to)443-453
Number of pages11
JournalGenes and Genetic Systems
Issue number6
Publication statusPublished - 2008

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Genetics


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