The tomato WRKY-B transcription factor modulates lateral branching by targeting BLIND, PIN4, and IAA15

Abstract

Lateral branching is a crucial agronomic trait that impacts crop yield. In tomato (Solanum lycopersicum), excessive lateral branching is unfavorable and results in substantial labor and management costs. Therefore, optimizing lateral branching is a primary objective in tomato breeding. Although many genes related to lateral branching have been reported in tomato, the molecular mechanism underlying their network remains elusive. In this study, we found that the expression profile of a WRKY gene, WRKY-B (for WRKY-BRANCING), was associated with the auxin-dependent axillary bud development process. Wrky-b mutants generated by the CRISPR/Cas9 editing system presented fewer lateral branches, while WRKY-B overexpression lines presented more lateral branches than did wild-type plants. Furthermore, WRKY-B can directly target the well-known branching gene BLIND (BL) and the auxin efflux carrier gene PIN4 to activate their expression. Both the bl and pin4 mutants exhibited reduced lateral branching, similar to the wrky-b mutant. The IAA contents in the axillary buds of the wrky-b, bl, and pin4 mutant plants were significantly higher than those in the wild-type plants. In addition, WRKY-B can also directly target the AUX/IAA gene IAA15 and repress its expression. In summary, WRKY-B works upstream of BL, PIN4, and IAA15 to regulate the development of lateral branches in tomato.

Acknowledgements

We acknowledge financial support from the Special Postdoctoral Funding from Heilongjiang Province (LBH-TZ2306); the National Natural Science Foundation of China (32002059), (32372705); the Key Research and Development Program of Ningxia (Special Talents) (2023BSB03024).

Author contributions

H.Y., J.J., and M.D. conceived and supervised the research. X.H., B.P., H.W., W.Y., X.X., and X.J. performed the experiments. H.Y., Q.W., K.Z., P.L., T.H., and L.L. conducted data analysis and drafted the manuscript. M.D., J.J., and J.L. revised the manuscript. The final version of the manuscript was reviewed and approved by all authors.

Data availability

The raw RNA-seq data have been deposited in Gene Expression Omnibus (GEO) of NCBI (https://www.ncbi.nlm.nih.gov/) under the accession number GSE164382. Other data analysed during the study was included in this article.

Conflict of interest statement

The authors all attest that there are no conflicts of interest, whether they be financial or personal in nature.

Supplementary data

Supplementary data is available at Horticulture Research online.

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