A novel <i>Arabidopsis</i> gene <i>RGAT1</i> is required for GA?mediated tapetum and pollen development

The phytohormone gibberellin (GA) is critical for anther development. RGA, a member of the DELLA family proteins that are central GA signalling repressors, key regulator male fertility in plants. However, downstream genes GA–RGA-mediated development remain to be characterised. We identified RGA Target 1 (RGAT1), novel Arabidopsis gene, functions as an important RGA-regulated target pollen RGAT1 predominantly expressed tapetum and microspores during stages 8–11, can directly activated by suppressed inflorescence apices. Both loss function gain led abnormal development, resulting abortive short siliques. In RGAT1-knockdown overexpression lines, abortion occurred at stage 10. Loss induced premature degeneration tapetal cells with defective ER-derived tapetosomes, while delayed degeneration. TUNEL assay confirmed participates timely programmed cell death. Moreover, reducing expression partially rescued developmental defects GA-deficient ga1-3 mutant. Our findings revealed direct plays essential role GA-mediated