The homeostasis of gibberellin (GA) is crucial for the normal development of anthers, but its underlying regulatory mechanisms are not clear. The GA induced v-Myb myeloblastosis viral oncogene homolog (MYB) transcription factor LoMYB65 is involved in anther development. In this study, we screened and identified an interacting protein of LoMYB65, Lilium Oriental Hybrids BEL1-Like Homeodomain6 (LoBLH6). LoBLH6 was localized in both the nucleus and cytoplasm, and it interacted with LoMYB65 through its BELL domain, exhibiting transcriptional repression activity. LoBLH6 was continuously expressed during anther development, with particularly high expression in the mid and late stages. In situ hybridization revealed high expression of LoBLH6 in the tapetum and microspores, with the same tissue specificity as LoMYB65. Silencing of LoBLH6 in lilies resulted in abnormal anther development, reduced pollen, and increased GA content. The application of GA induced phenotypes in the anthers and pollen of lily that were similar to the silencing of LoBLH6. Further research showed that LoBLH6 directly binds to the promoter of Lilium Oriental Hybrids GA 20-oxidase1 (LoGA20ox1) to suppress its expression, and co-expression with LoMYB65 enhances this repression. Additionally, GA treatment enhanced the interaction between LoBLH6 and LoMYB65 and their complex's inhibitory effect on downstream target genes. During the transition from microspores to mature pollen grains in lily anthers, GA levels maintain a steady state, which is disrupted by silencing LoBLH6, leading to abnormal pollen development. Overall, our results reveal that the interaction between LoBLH6 and LoMYB65 regulates anther development through feedback regulation of GA synthesis.

中文翻译：

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LoBLH6 与 LoMYB65 相互作用，通过反馈调节百合赤霉素合成来调节花药发育


赤霉素 （GA） 的稳态对花药的正常发育至关重要，但其潜在的调节机制尚不清楚。GA 诱导的 v-Myb 成髓细胞增多症病毒癌基因同源物 （MYB） 转录因子 LoMYB65 参与花药发育。在这项研究中，我们筛选并鉴定了 LoMYB65 的一种相互作用蛋白，即 Lilium Oriental Hybrids BEL1-Like Homeodomain6 （LoBLH6）。LoBLH6 位于细胞核和细胞质中，并通过其 BELL 结构域与 LoMYB65 相互作用，表现出转录抑制活性。LoBLH6 在花药发育过程中持续表达，中晚期表达量特别高。原位杂交显示 LoBLH6 在绒毡层和小孢子中高表达，与 LoMYB65 具有相同的组织特异性。百合中 LoBLH6 的沉默导致花药发育异常，花粉减少，GA 含量增加。GA 的应用诱导了百合花药和花粉中的表型，类似于 LoBLH6 的沉默。进一步的研究表明，LoBLH6 直接与 Lilium Oriental Hybrids GA 20-oxidase1 （LoGA20ox1） 的启动子结合以抑制其表达，与 LoMYB65 的共表达增强了这种抑制。此外，GA 处理增强了 LoBLH6 和 LoMYB65 之间的相互作用及其复合物对下游靶基因的抑制作用。在百合花药从小孢子过渡到成熟花粉粒的过程中，GA 水平保持稳定状态，被沉默 LoBLH6 破坏，导致花粉发育异常。总体而言，我们的结果表明，LoBLH6 和 LoMYB65 之间的相互作用通过对 GA 合成的反馈调节来调节花药发育。