J Integr Plant Biol ›› 2024, Vol. 66 ›› Issue (4): 749-770.DOI: 10.1111/jipb.13627

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  • 收稿日期:2023-10-24 接受日期:2024-01-13 出版日期:2024-04-01 发布日期:2024-04-13

SlBEL11 regulates flavonoid biosynthesis, thus fine-tuning auxin efflux to prevent premature fruit drop in tomato

Xiufen Dong1,2,3†, Xianfeng Liu1,4†, Lina Cheng1,4, Ruizhen Li1,4, Siqi Ge1,4, Sai Wang1,4, Yue Cai1,4, Yang Liu1,4, Sida Meng1,4, Cai-Zhong Jiang5,6, Chun-Lin Shi7, Tianlai Li1,4, Daqi Fu8, Mingfang Qi1,4* and Tao Xu1,4*   

  1. 1. College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China;
    2. Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province, College of Horticulture Science, Zhejiang A&F University, Hangzhou 311300, China;
    3. Key Laboratory for Quality and Safety Control of Subtropical Fruits and Vegetables, Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province, Ministry of Agriculture and Rural Affairs, College of Horticulture Science, Zhejiang A&F University, Hangzhou 311300, China;
    4. Key Laboratory of Protected Horticulture of Ministry of Education, Shenyang 110866, China;
    5. Crops Pathology and Genetic Research Unit, United States Department of Agriculture Agricultural Research Service, Washington, DC 20250, USA;
    6. Department of Plant Sciences, University of California, Davis, CA 95616, USA;
    7. ANGENOVO, Oslo 0753, Norway;
    8. Laboratory of Fruit Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
    †These authors contributed equally to this work.
    *Correspondences:Mingfang Qi(qimingfang@126.com);Tao Xu(syauxutao@syau.edu.cn, Dr. Xu is fully responsible for the distributions of all materials associated with this article)
  • Received:2023-10-24 Accepted:2024-01-13 Online:2024-04-01 Published:2024-04-13

Abstract: Auxin regulates flower and fruit abscission, but how developmental signals mediate auxin transport in abscission remains unclear. Here, we reveal the role of the transcription factor BEL1-LIKE HOMEODOMAIN11 (SlBEL11) in regulating auxin transport during abscission in tomato (Solanum lycopersicum). SlBEL11 is highly expressed in the fruit abscission zone, and its expression increases during fruit development. Knockdown of SlBEL11 expression by RNA interference (RNAi) caused premature fruit drop at the breaker (Br) and 3d post-breaker (Br+3) stages of fruit development. Transcriptome and metabolome analysis of SlBEL11-RNAi lines revealed impaired flavonoid biosynthesis and decreased levels of most flavonoids, especially quercetin, which functions as an auxin transport inhibitor. This suggested that SlBEL11 prevents premature fruit abscission by modulating auxin efflux from fruits, which is crucial for the formation of an auxin response gradient. Indeed, quercetin treatment suppressed premature fruit drop in SlBEL11-RNAi plants. DNA affinity purification sequencing (DAP-seq) analysis indicated that SlBEL11 induced expression of the transcription factor gene SlMYB111 by directly binding to its promoter. Chromatin immunoprecipitation-quantitative polymerase chain reaction and electrophoretic mobility shift assay showed that S. lycopersicum MYELOBLASTOSIS VIRAL ONCOGENE HOMOLOG111 (SlMYB111) induces the expression of the core flavonoid biosynthesis genes SlCHS1, SlCHI, SlF3H, and SlFLS by directly binding to their promoters. Our findings suggest that the SlBEL11-SlMYB111 module modulates flavonoid biosynthesis to fine-tune auxin efflux from fruits and thus maintain an auxin response gradient in the pedicel, thereby preventing premature fruit drop.

Key words: abscission, auxin, flavonoid, SlBEL11, tomato

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