J Integr Plant Biol ›› 2024, Vol. 66 ›› Issue (6): 1206-1226.DOI: 10.1111/jipb.13646

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  • 收稿日期:2023-12-15 接受日期:2024-03-01 出版日期:2024-06-01 发布日期:2024-06-25

The transcriptional control of LcIDL1-LcHSL2 complex by LcARF5 integrates auxin and ethylene signaling for litchi fruitlet abscission

Xingshuai Ma1†, Zidi He1†, Ye Yuan2†, Zhijian Liang1, Hang Zhang1, Vilde Olsson Lalun3, Zhuoyi Liu1, Yanqing Zhang4, Zhiqiang Huang1, Yulian Huang1, Jianguo Li1* and Minglei Zhao1*   

  1. 1. State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangdong Laboratory for Lingnan Modern Agriculture, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (South China), Ministry of Agriculture and Rural Affairs, Guangdong Litchi Engineering Research Center, College of Horticulture, South China Agricultural University, Guangzhou 510642, China;
    2. Dongguan Botanical Garden, Dongguan 523128, China;
    3. Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Blindernveien 31, Oslo 0316, Norway;
    4. College of Agriculture, Guangxi University, Nanning 530004, China
    †These authors contributed equally to this work.
    *Correspondences: Jianguo Li (jianli@scau.edu.cn); Minglei Zhao (zml503@scau.edu.cn, Dr. Zhao is fully responsible for the distributions of all materials associated with this article)
  • Received:2023-12-15 Accepted:2024-03-01 Online:2024-06-01 Published:2024-06-25

Abstract: At the physiological level, the interplay between auxin and ethylene has long been recognized as crucial for the regulation of organ abscission in plants. However, the underlying molecular mechanisms remain unknown. Here, we identified transcription factors involved in indoleacetic acid (IAA) and ethylene (ET) signaling that directly regulate the expression of INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) and its receptor HAESA (HAE), which are key components initiating abscission. Specifically, litchi IDA-like 1 (LcIDL1) interacts with the receptor HAESA-like 2 (LcHSL2). Through in vitro and in vivo experiments, we determined that the auxin response factor LcARF5 directly binds and activates both LcIDL1 and LcHSL2. Furthermore, we found that the ETHYLENE INSENSITIVE 3-like transcription factor LcEIL3 directly binds and activates LcIDL1. The expression of IDA and HSL2 homologs was enhanced in LcARF5 and LcEIL3 transgenic Arabidopsis plants, but reduced in ein3 eil1 mutants. Consistently, the expressions of LcIDL1 and LcHSL2 were significantly decreased in LcARF5- and LcEIL3-silenced fruitlet abscission zones (FAZ), which correlated with a lower rate of fruitlet abscission. Depletion of auxin led to an increase in 1-aminocyclopropane-1-carboxylic acid (the precursor of ethylene) levels in the litchi FAZ, followed by abscission activation. Throughout this process, LcARF5 and LcEIL3 were induced in the FAZ. Collectively, our findings suggest that the molecular interactions between litchi AUXIN RESPONSE FACTOR 5 (LcARF5)-LcIDL1/LcHSL2 and LcEIL3-LcIDL1 signaling modules play a role in regulating fruitlet abscission in litchi and provide a long-sought mechanistic explanation for how the interplay between auxin and ethylene is translated into the molecular events that initiate abscission.

Key words: auxin, ethylene, fruit abscission, IDA-HAE/HSL2, litchi

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