Qi Xiaolong, Guo Shuwei, Wang Dong, Zhong Yu, Chen Ming, Chen Chen, Cheng Dehe, Liu Zongkai, An Tai, Li Jinlong, Jiao Yanyan, Wang Yuwen, Liu Jinchu, Zhang Yuling, Chen Shaojiang, Liu Chenxu
National Maize Improvement Center of China, Key Laboratory of Crop Heterosis and Utilization (MOE), China Agricultural University, Beijing, 100193, China.
Plant J. 2022 May;110(3):849-862. doi: 10.1111/tpj.15708. Epub 2022 Mar 8.
In higher plants, the generation and release of viable pollen from anthers is vital for double fertilization and the initiation of seed development. Thus, the characterization of genes related to pollen development and anther dehiscence in plants is of great significance. The F-box protein COI1 plays a crucial role in the jasmonate (JA) signaling pathway and interacts with many JAZ family proteins in the presence of jasmonoyl-isoleucine (JA-Ile) or coronatine (COR). The mutation of AtCOI1 in Arabidopsis leads to defective anther dehiscence and male sterility (MS), although COI has not been shown to affect fertility in Zea mays (maize). Here we identified two genes, ZmCOI2a and ZmCOI2b, that redundantly regulate gametophytic male fertility. Both ZmCOI2a and ZmCOI2b are highly homologous and constitutively expressed in all tissues tested. Subcellular localization revealed that ZmCOI2a and ZmCOI2b were located in the nucleus. The coi2a coi2b double mutant, generated by CRISPR/Cas9, had non-dehiscent anthers, delayed anther development and MS. In addition, coi2a coi2b male gametes could not be transmitted to the next generation because of severe defects in pollen germination. The JA content of coi2a coi2b anthers was unaltered compared with those of the wild type, and the exogenous application of JA could not rescue the fertility defects of coi2a coi2b. Transcriptome analysis showed that the expression of genes involving the JA signaling transduction pathway, including ZmJAZ3, ZmJAZ4, ZmJAZ5 and ZmJAZ15, was affected in coi2a coi2b. However, yeast two-hybrid assays showed that ZmJAZs interacted with ZmCOI1s, but not with ZmCOI2s. In conclusion, ZmCOI2a and ZmCOI2b redundantly regulate anther dehiscence and gametophytic male fertility in maize.
在高等植物中，花药产生并释放有活力的花粉对于双受精和种子发育的起始至关重要。因此，鉴定与植物花粉发育和花药开裂相关的基因具有重要意义。F-box蛋白COI1在茉莉酸（JA）信号通路中起关键作用，并且在茉莉酰异亮氨酸（JA-Ile）或冠菌素（COR）存在的情况下与许多JAZ家族蛋白相互作用。拟南芥中AtCOI1的突变会导致花药开裂缺陷和雄性不育（MS），尽管尚未证明COI会影响玉米的育性。在此，我们鉴定了两个基因ZmCOI2a和ZmCOI2b，它们冗余调控配子体雄性育性。ZmCOI2a和ZmCOI2b高度同源，并且在所有测试组织中组成型表达。亚细胞定位显示ZmCOI2a和ZmCOI2b定位于细胞核。通过CRISPR/Cas9产生的coi2a coi2b双突变体具有不开裂的花药、延迟的花药发育和雄性不育。此外，由于花粉萌发存在严重缺陷，coi2a coi2b雄配子无法传递到下一代。与野生型相比，coi2a coi2b花药的JA含量未改变，并且外源施用JA无法挽救coi2a coi2b的育性缺陷。转录组分析表明，在coi2a coi2b中，涉及JA信号转导途径的基因（包括ZmJAZ3、ZmJAZ4、ZmJAZ5和ZmJAZ15）的表达受到影响。然而，酵母双杂交试验表明，ZmJAZ与ZmCOI1相互作用，但不与ZmCOI2相互作用。总之，ZmCOI2a和ZmCOI2b在玉米中冗余调控花药开裂和配子体雄性育性。
