The auxin‐responsive CsSPL9‐CsGH3.4 module finely regulates auxin levels to suppress the development of adventitious roots in tea (Camellia sinensis)

• Published in: The Plant journal : for cell and molecular biology 2024-09, Vol.119 (5), p.2273-2287
• Main Authors: Wang, Wenzhao, Jiao, Mengmin, Huang, Xue, Liang, Wenjuan, Ma, Zhonglian, Lu, Zhanling, Tian, Shenyang, Gao, Xiuhua, Fan, Li, He, Xinyue, Bao, Junhua, Yu, Youben, Zhang, Dong, Bao, Lu
• Format: Article
• Language: English
• Subjects: Acetic acid; adventitious root; auxin; Auxins; Breeding; Breeding methods; Camellia sinensis; Camellia sinensis - genetics; Camellia sinensis - growth & development; Camellia sinensis - metabolism; Cultivation techniques; Cuttings; Gene Expression Regulation, Plant; Gretchen Hagen 3; indole acetic acid; Indoleacetic acid; Indoleacetic Acids - metabolism; Modules; Naphthaleneacetic acid; Naphthaleneacetic Acids - pharmacology; Plant Growth Regulators - metabolism; Plant Proteins - genetics; Plant Proteins - metabolism; Plant Roots - genetics; Plant Roots - growth & development; Plant Roots - metabolism; Promoter Regions, Genetic; Roots; Seedlings; Seedlings - genetics; Seedlings - growth & development; Seedlings - metabolism; squamosa promoter‐binding protein‐like; Tea; transcription factors; Transcription Factors - genetics; Transcription Factors - metabolism
• ISSN: 0960-7412; 1365-313X; 1365-313X
• DOI: 10.1111/tpj.16916

SUMMARY The cutting technique is extensively used in tea breeding, with key emphasis on promoting the growth of adventitious roots (ARs). Despite its importance in tea cultivation, the mechanisms underlying AR development in tea remain unclear. In this study, we demonstrated the essential role of auxins in the initiation and progression of AR and established that the application of exogenous 1‐naphthaleneacetic acid‐enhanced AR formation in tissue‐cultured seedlings and cuttings. Then, we found that the auxin‐responsive transcription factor CsSPL9 acted as a negative regulator of AR development by reducing the levels of free indole‐3‐acetic acid (IAA) in tea plants. Furthermore, we identified CsGH3.4 as a downstream target of CsSPL9, which was activated by direct binding to its promoter. CsGH3.4 also inhibited AR development and maintained low levels of free IAA. Thus, these results revealed the inhibitory effect of the auxin‐responsive CsSPL9‐CsGH3.4 module on AR development by reducing free IAA levels in tea. These findings have significant theoretical and practical value for enhancing tea breeding practices. Significance Statement The cutting technique is extensively used in tea breeding, with key emphasis on promoting the growth of adventitious roots (ARs). Despite its importance in tea cultivation, the mechanisms underlying AR development in tea remain unclear. In present study, we revealed the inhibitory effect of the auxin‐responsive CsSPL9‐CsGH3.4 module on AR development by reducing free IAA levels in tea. These findings have significant theoretical and practical value for enhancing tea and other woody plant breeding practices.