LcEIL2/3 are involved in fruitlet abscission via activating genes related to ethylene biosynthesis and cell wall remodeling in litchi

• Published in: The Plant journal : for cell and molecular biology Vol. 103; no. 4; pp. 1338 - 1350
• Main Authors: Ma, Xingshuai, Yuan, Ye, Wu, Qian, Wang, Jun, Li, Jianguo, Zhao, Minglei
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.08.2020
• Subjects: Abscission; Arabidopsis; Biosynthesis; Cell Wall - metabolism; cell wall remodeling; Cell walls; Electrophoretic mobility; Ethylene; ethylene biosynthesis; ethylene production; Ethylenes - biosynthesis; flowers; Flowers - metabolism; Flowers - physiology; Fruit - metabolism; Fruit - physiology; Fruit crops; fruit drop; fruitlet abscission; Fruits; gel electrophoresis; Gene expression; Genes; Genes, Plant - physiology; Homology; LcEIL2/3; litchi (Litchi chinensis Sonn.); Litchi - metabolism; Litchi chinensis; luciferase; Phylogeny; Plant Growth Regulators - biosynthesis; Plant hormones; Plant Proteins - metabolism; Plant Proteins - physiology; Plants, Genetically Modified; Transcription Factors - metabolism; Transcription Factors - physiology; cell wall remodeling; ethylene biosynthesis; fruitlet abscission; LcEIL2/3; litchi (Litchi chinensis Sonn.)
• ISSN: 0960-7412; 1365-313X; 1365-313X
• DOI: 10.1111/tpj.14804

Summary Fruit crops are subject to precocious fruit abscission, during which the phytohormone ethylene (ET) acts as a major positive regulator. However, the molecular basis of ET‐induced fruit abscission remains poorly understood. Here, we show that two ETHYLENE INSENSITIVE 3‐like (EIL) homologs in litchi, LcEIL2 and LcEIL3, play a role in ET‐activated fruitlet abscission. LcEIL2/3 were significantly upregulated in the fruit abscission zone (AZ) during the ET‐induced fruitlet abscission in litchi. The presence of LcEIL2/3 in wild‐type Arabidopsis and ein3 eil1 mutants can accelerate the floral organ abscission. Moreover, the electrophoretic mobility shift assay and dual luciferase reporter analysis illustrated that LcEIL2/3 directly interacted with the gene promoters to activate the expression of cell wall remodeling genes LcCEL2/8 and LcPG1/2, and ET biosynthetic genes LcACS1/4/7 and LcACO2/3. Furthermore, we showed that LcPG1/2 were expressed in the floral abscission zone of Arabidopsis, and constitutive expression of LcPG2 in Arabidopsis promoted the floral organ abscission. In conclusion, we propose that LcEIL2/3 are involved in ET‐induced fruitlet abscission via controlling expression of genes related to ET biosynthesis and cell wall remodeling in litchi. Siginificance Statement Ethylene has been uncovered to act as the main inducer of fruit abscission in many important fruit crops such as apple, citrus and grape. However, the mechanism of ethylene‐induced abscission remains elusive. Here we identified two ETHYLENE INSENSITIVE 3‐like (EIL) homologs in litchi, LcEIL2 and LcEIL3, which act as positive regulators in abscission. We propose that LcEIL2/3 are involved in ethylene‐induced fruitlet abscission via controlling expression of genes related to ethylene biosynthesis and cell wall remodeling in litchi.