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Journal of Integrative Agriculture  2025, Vol. 24 Issue (8): 3040-3054    DOI: 10.1016/j.jia.2025.03.022
Horticulture Advanced Online Publication | Current Issue | Archive | Adv Search |
CaBBX9, an interaction partner of autophagy-related protein CaATG8c, negatively regulates the heat tolerance of pepper

Li Zhang1, Yuling Guo1, Sitian Wang1, Zhenze Wang1, Qiaomin Yang1, Ying Li1, Yue Zhao1, Haiyan Li1, Lijun Cao2, 3, Minghui Lu1#

1 College of Horticulture, Northwest A&F University, Yangling 712100, China

2 Department of Biology, Duke University, Durham, NC 27708, USA

3 Howard Hughes Medical Institute, Duke University, Durham, NC 27708, USA

 Highlights 
Pepper zinc-finger protein CaBBX9 interacts with autophagy-related protein CaATG8c and exhibits a transcriptional activity.
Silencing and overexpression of CaBBX9 indicate that it negatively regulates heat tolerance of pepper plants.
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摘要  

为了探索自噬对辣椒耐热性贡献的分子机制,在之前的研究中,我们鉴定了锌指蛋白B-BOX 9/CONSTANS-LIKE 13(CaBBX9/CaCOL13)作为自噬调节蛋白(ATG)CaATG8c的相互作用伴侣,其中CaATG8c是自噬的核心组分之一。然而,CaBBX9在自噬和耐热性中的作用尚不清楚。在这项研究中,我们进一步证实了CaBBX9与CaATG8c之间的相互作用,并定义了CaBBX9的相互作用区域是CCT结构域以及特定片段区域。热处理可以诱导CaBBX9的表达,并发现CaBBX9与CaATG8c在细胞核中共定位且表现出转录活性。当沉默CaBBX9时,辣椒的耐热性增强,表现为MDA含量、H2O2、死细胞和相对电解质渗漏的减少以及叶绿素含量和热胁迫相关基因表达水平的增加。在番茄中过表达CaBBX9则显示出相反的效果。综上所述,我们的研究表明,CaBBX9通过加剧氧化损伤和抑制热相关基因的表达来负向调节辣椒的耐热性。我们的发现为指导作物对不利环境的耐受性育种提供了新的线索。



Abstract  

To explore the molecular mechanisms by which autophagy contributes to pepper’s heat tolerance, we previously identified the zinc-finger protein B-BOX 9/CONSTANS-LIKE 13 (CaBBX9/CaCOL13) as an interaction partner of the autophagy related protein (ATG) CaATG8c, a core component in autophagy.  However, the involvement of CaBBX9 in both autophagy and heat tolerance remains unclear.  In this study, we further confirmed the interaction between CaBBX9 and CaATG8c and defined the interaction regions of CaBBX9 as CONSTANS, CONSTANS-Like, and TOC1 (CCT) domain and the fragment region.  The expression of CaBBX9 can be induced by heat treatment.  CaBBX9 is co-localized with CaATG8c in the nucleus and exhibits a transcriptional activity.  When the expression of CaBBX9 is silenced, the heat tolerance of pepper is enhanced, shown by the decrement of MDA content, H2O2 and dead cells accumulation, and relative electrolyte leakage, along with the increment of chlorophyll content and expression level of heat-tolerance-related genes.  Overexpression of CaBBX9 in tomatoes displays the opposite effects.  Taken together, we demonstrate that CaBBX9 negatively regulates the heat tolerance of peppers by exacerbating oxidative damage and inhibiting the expression of heat-related genes.  Our findings provide a new clue for guiding crop breeding for pepper tolerance to heat stress.


Keywords:  pepper       CaBBX9        CaATG8c        Heat tolerance        Autophagy  
Received: 15 March 2024   Online: 27 March 2025   Accepted: 11 March 2025
Fund: This work was supported by a grant from the National Natural Science Foundation of China (32172552, 31572114) and the earmarked fund for the China Agriculture Research System (CARS-23-G22).
About author:  Li Zhang, E-mail: zl236426@163.com; #Correspondence Minghui Lu, E-mail: xnjacklu@nwsuaf.edu.cn

Cite this article: 

Li Zhang, Yuling Guo, Sitian Wang, Zhenze Wang, Qiaomin Yang, Ying Li, Yue Zhao, Haiyan Li, Lijun Cao, Minghui Lu. 2025. CaBBX9, an interaction partner of autophagy-related protein CaATG8c, negatively regulates the heat tolerance of pepper. Journal of Integrative Agriculture, 24(8): 3040-3054.

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