The underlying pathway involved in inter-subspecific hybrid male sterility in rice.

f5 locus in rice (Oryza sativa L.) confers significant effects on hybrid male sterility and segregation distortion. BC14 F2 plants with f5-i/i, f5-j/j and f5-i/j genotypes were used to dissect the underlying pathway of f5-caused hybrid male sterility via comparative transcriptome analysis. A total of 350, 421, and 480 differentially expressed genes (DEGs) were identified from f5-i/j vs f5-j/j, f5-j/j vs f5-i/i, and f5-i/j vs f5-i/i, respectively. 145 DEGs were identified simultaneously in f5-i/j vs f5-j/j and f5-i/j vs f5-i/i. Enrichment analysis indicated that stress and cell control related processes were enriched. The expression of ascorbate peroxidase (APX) and most of the heat shock proteins (HSPs) were decreased, which might result in higher sensitivity to various stresses in pollen cells. A model was proposed to summarize the underlying process for f5-caused hybrid male sterility. These results would provide significant clues to further dissecting the molecular mechanism of f5-caused inter-subspecific reproductive isolation.