Genome-Wide Comprehensive Survey of the Subtilisin-Like Proteases Gene Family Associated With Rice Caryopsis Development.

Subtilisin-like proteases (SUBs), which are extensively distributed in three life domains, affect all aspects of the plant life cycle, from embryogenesis and organogenesis to senescence. To explore the role of SUBs in rice caryopsis development, we recharacterized the gene family in rice ( ssp. ). In addition, investigation of the was conducted across cultivated and wild rice in seven other diploid species (, , , , , , and ssp. ). Sixty-two were identified in the latest ssp. genome, which was higher than that observed in wild species. The gene family was classified into six evolutionary branches, and SUB1 and SUB3 possessed all tandem duplication (TD) genes. All paralogous in eight plants underwent significant purifying selection. The expansion of in cultivated rice was primarily associated with the occurrence of tandem duplication events and purifying selection and may be the result of rice domestication. Combining the expression patterns of in different rice tissues and qRT-PCR verification, four were expressed in rice caryopses. Moreover, expressed in rice caryopses possessed an earlier origin in , and the gene cluster formed by together with the surrounding gene blocks may be responsible for the specific expression of in caryopses. All the above insights were inseparable from the continuous evolution and domestication of . Together, our findings not only contribute to the understanding of the evolution of SUBs in cultivated and wild rice but also lay the molecular foundation of caryopsis development and engineering improvement of crop yield.