Cai Zhengzheng, Su Yuanyuan, Kong Lan, Ren Guangxin, Zheng Lili, Zhu Miaomiao, Qiu Bingwen, Hong Zonglie, Ye Yanfang, Xue Yongbiao, Wu Weiren, Duan Yuanlin
Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops and Fujian Provincial Key Laboratory of Breeding by Design of Plant, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Institute of Crops, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, China.
Plant J. 2025 Jul;123(1):e70346. doi: 10.1111/tpj.70346.
JAGGED (JAG) and DROOPING LEAF (DL) are two key regulators of floral organ pattern in rice, but how they work together in establishing reproductive organs and terminating FM remains to be determined. Here, we have analyzed the coordination mechanism in detail. While the floral meristem (FM) determinacy is severely compromised in null-allele jag and dl spikelets, jag dl exhibits a complete loss of FM determinacy, with a large bouquet composed of lemma-like organs sprouting from the center of spikelets replacing the stamen and pistil, indicating that they synergistically determine sexual organ identity and FM termination. Protein-protein interactions revealed that JAG binds to SUPERWOMAN1 (SPW1)/OsMADS16 and DL, forming two heterodimers, JAG-SPW1 and JAG-DL. Expression analysis revealed that JAG binds to the promoters of both DL and SPW1 and directly activates SPW1, while SPW1 and DL do not directly inhibit each other. However, JAG-SPW1 inhibits DL transcription, while JAG-DL inhibits SPW1 transcription, indicating that JAG may mediate the transcription antagonism through these two heterodimers to limit the transcription of DL in stamen and SPW1 in pistil, which is crucial for sexual organ origination in the appropriate location. Meanwhile, JAG and DL can directly inhibit OSH1 and OSH15, individually or synergistically, which is essential for timely termination of FM. These findings reveal the unique synergistic manner of JAG and DL in rice reproductive organ generation, providing insights into the regulatory mechanisms of floral morphogenesis in plants.
锯齿叶（JAG）和垂叶（DL）是水稻花器官模式的两个关键调节因子，但它们如何协同作用以建立生殖器官并终止花分生组织（FM）仍有待确定。在此，我们详细分析了其协调机制。虽然在JAG和DL无效等位基因的小穗中花分生组织（FM）的确定性严重受损，但JAG DL表现出FM确定性的完全丧失，从小穗中心萌发出由类似外稃的器官组成的大花束取代了雄蕊和雌蕊，这表明它们协同决定性器官的特征和FM的终止。蛋白质 - 蛋白质相互作用表明，JAG与超人1（SPW1）/ OsMADS16和DL结合，形成两个异二聚体，JAG - SPW1和JAG - DL。表达分析表明，JAG与DL和SPW1的启动子结合并直接激活SPW1，而SPW1和DL并不直接相互抑制。然而，JAG - SPW1抑制DL转录，而JAG - DL抑制SPW1转录，这表明JAG可能通过这两个异二聚体介导转录拮抗作用，以限制雄蕊中DL和雌蕊中SPW1的转录，这对于性器官在适当位置的起源至关重要。同时，JAG和DL可以单独或协同直接抑制OSH1和OSH15，这对于及时终止FM至关重要。这些发现揭示了JAG和DL在水稻生殖器官生成中的独特协同方式，为植物花形态发生的调控机制提供了见解。
