| Summary: | The biological process of anther development is very complex. It remains largely unclear how the cinnamoyl–CoA reductase (CCR) encoding genes function in the regulation of anther development in plants. Here, we establish that the CCR family gene <i>OsCCR18</i> is essential for maintaining male fertility in rice. The <i>OsCCR18</i> transcripts were greatly abundant in the panicles at the S4 and S5 developmental stages in rice. The subcellular localization of OsCCR18 proteins was in the nucleus of the rice. The knockout of the <i>OsCCR18</i> gene resulted in a severely abnormal degradation of the tapetum as well as the abnormal development of granular Ubisch bodies, leading to the inability to form normal pollen in the mutants. Compared with the wild–type (WT) rice, the <i>osccr18</i> mutants had no visible pollen grains and had entirely male sterility. Furthermore, several anther development–related genes, including <i>OsPDA1</i>, <i>OsDTD</i>, <i>OsC6</i>, <i>OsACOS12</i>, <i>OsTDR</i>, <i>OsWDA1</i>, <i>OsDPW</i>, <i>OsCYP703A3</i>, and <i>OsNOP</i>, were significantly lower expressed in the panicles at the stages from S5 to S8 in the <i>osccr18</i> mutants than in the WT plants. Additionally, hundreds of genes involved in phenylpropanoid biosynthesis, fatty acid synthesis and metabolism exhibited distinct expression patterns between the WT and mutants, which may be crucial for controlling anther development in rice. These findings add a new regulatory role to CCR family gene–mediated male fertility in rice.
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