LoBLH6 interacts with LoMYB65 to regulate anther development through feedback regulation of gibberellin synthesis in lily

Abstract

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 coexpression 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.

Acknowledgements

This research was supported by the National Key Research and Development Program of China (2022YFD1200500), the `JBGS' Project of Seed Industry Revitalization in Jiangsu Province (JBGS[2021]093), and the Project for Crop Germplasm Resources Conservation of Jiangsu Province (2021-SJ-011).

Author contributions

N.T., J.Y., Z.W., and J.L. conceived this project and designed all research; J.Y. performed the experiments together with X.L., Q.F., and X.P. under the supervisor of N.T.; J.Y. performed data processing; S.X. provided bioinformatics analysis technology; M.H. cultivated plant materials; J.Y. wrote the first draft of the article; all authors read and revised the article.

Data availability

The data and figures in this study can be found in the article and its supporting materials.

Competing interest statement

All authors disclosed no relevant relationships.

Supplementary Data

Supplementary data is available at Horticulture Research online.

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