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Journal of Integrative Agriculture  2026, Vol. 25 Issue (1): 118-126    DOI: 10.1016/j.jia.2025.03.018
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SlIDL6–SlHSL1/2/3 ligand-receptor pairs regulate tomato pedicel abscission

Yanyun Tu1, Lina Cheng1, Xianfeng Liu1, Marta Hammerstad2, Chunlin Shi3, Sida Meng1, Mingfang Qi1, Tianlai Li1, Tao Xu1#

1 College of Horticulture/Key Laboratory of Protected Horticulture of Ministry of Education/Modern Protected Horticulture Engineering & Technology Center, Shenyang Agricultural University, Shenyang 110866, China

2 Department of Biosciences, University of Oslo, Oslo 0371, Norway

3 ANGENOVO AS, Oslo 0753, Norway

 Highlights 
We isolated three HAESA-like homologs, SlHSL1/2/3, which are involved in tomato flower abscission.
SlHSL1/2/3 are the receptors of SlIDL6 in pedicel abscission and flower abscission under low light.
Ethylene action inhibitor 1-methylcyclopropene (1-MCP) can significantly depress the expression of SlHSL1/2/3, and the abscission regulated by SlHSL1/2/3 is partially dependent on ethylene.
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摘要  
落花落果使作物产量降低,因此减少花果脱落是一个重要的农业问题。HAESA(HAE)和HAESA-like2(HSL2)受体激酶及其配体IDA小肽是调控拟南芥花器官脱落的核心。我们早期研究表明,SlIDL6是番茄中IDA的同源物,其功能与AtIDA相似,可以调控番茄花器官脱落。在本研究中,我们发现三个与番茄花柄脱落相关的HAESA-like同源物SlHSL1/2/3。SlHSL1/2/3在离区(AZ)高表达。Slhsl1Slhsl2Slhsl3的敲除株系花柄外植体脱落显著慢于野生型(WT)。双突变体Slhsl1Slhsl2Slhsl1Sslhsl3Slhsl2Slhsl比单基因敲除株系进一步抑制了花柄脱落,且三突变体Slhsl1sl1Slhsl2Slhsl3的脱落率更低,表明在番茄花柄脱落过程中SlHSL1/2/3的功能是部分冗余的。用SlIDL6小肽处理番茄花柄外植体显著加速了WT的花柄脱落,但对SlHSL1/2/3敲除系的脱落率影响不大,表明在番茄花柄脱落中SlHSL1/2/3作为SlIDL6的受体发挥作用。乙烯抑制剂1-甲基环丙烯(1-MCP)可显著抑制SlHSL1/2/3的表达。在乙烯处理的情况下,乙烯显著加速WT花柄脱落,而SlHSL1/2/3敲除系的脱落率显著低于WT。综上所述,我们的研究结果表明,SlHSL1/2/3可以作为SlIDL6的受体,正调控番茄花柄脱落,且SlHSL1/2/3调控的脱落部分依赖于乙烯。




Abstract  

Flower and fruit abscission reduce crop yield, so decreasing abscission is a significant agricultural issue.  HAESA (HAE) and HAESA-like2 (HSL2) kinases and their ligand, INFLORESCENCE DEFICIENT IN ABSCISSION (IDA) peptide, have been confirmed to be the core elements regulating floral organ abscission in Arabidopsis thaliana.  Our earlier research revealed that SlIDL6, a homolog of IDA in tomato, functions similarly to AtIDA, regulating the abscission of tomato flower organs.  Here, we further isolated three HAESA-like homologs, SlHSL1/2/3, which are involved in tomato flower abscission.  SlHSL1/2/3 are highly expressed in the abscission zone (AZ).  The knockout mutant lines of Slhsl1, Slhsl2, and Slhsl3 showed lower flower pedicel abscission than wild type (WT).  The double mutant of Slhsl1Slhsl2, Slhsl1Slhsl3, and Slhsl2Slhsl3 further depressed abscission than each of the single mutant lines, while triple mutants Slhsl1Slhsl2Slhsl3 exhibited the lowest abscission, indicating that SlHSL1/2/3 mediated abscission is non-redundancy, at least partially.  Treating tomato pedicel explants with SlIDL6 peptide significantly accelerated pedicel abscission in WT.  However, it had little effect on the abscission rate of SlHSL1/2/3 knockout lines, indicating that SlHSL1/2/3 are the receptors of SlIDL6 in pedicel abscission.  Ethylene action inhibitor 1-methylcyclopropene (1-MCP) can significantly depress the expression of SlHSL1/2/3.  Ethylene can significantly accelerate the abscission of WT, while less abscission was found in SlHSL1/2/3 knockout lines.  Our findings indicate that SlHSL1/2/3 can act as receptors for SlIDL6 to positively regulate tomato pedicel abscission, and the abscission regulated by SlHSL1/2/3 was partially dependent on ethylene

Keywords:  tomato       abscission       SlHSL       SlIDL6       Ethylene  
Received: 04 November 2024   Accepted: 14 February 2025 Online: 22 March 2025  
Fund: 
This work was supported by the Liaoning Science and Technology Innovation Team Project, China (JYTTD2024007).
About author:  #Correspondence Tao Xu, E-mail: syauxutao@syau.edu.cn

Cite this article: 

Yanyun Tu, Lina Cheng, Xianfeng Liu, Marta Hammerstad, Chunlin Shi, Sida Meng, Mingfang Qi, Tianlai Li, Tao Xu. 2026. SlIDL6–SlHSL1/2/3 ligand-receptor pairs regulate tomato pedicel abscission. Journal of Integrative Agriculture, 25(1): 118-126.

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