Identifying the role of cellulase gene CsCEL20 upon the infection of Xanthomonas citri subsp. citri in citrus.

IF 2.6 3区农林科学 Q1 AGRONOMY

Molecular Breeding Pub Date : 2025-01-06 eCollection Date: 2025-01-01 DOI:10.1007/s11032-024-01531-3

Yi Li, Huijie Lou, Hongyan Fu, Hanying Su, Chenxing Hao, Jianming Luo, Nan Cai, Yan Jin, Jian Han, Ziniu Deng, Yunlin Cao, Xianfeng Ma

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Abstract

Citrus canker is a devastating disease caused by Xanthomonas citri subsp. citri (Xcc), which secretes the effector PthA4 into host plants to trigger transcription of the susceptibility gene CsLOB1, resulting in pustule formation. However, the molecular mechanism underlying CsLOB1-mediated susceptibility to Xcc remains elusive. This study identified CsCEL20 as a target gene positively regulated by CsLOB1. Cell expansion and cell wall degradation were observed in sweet orange leaves after Xcc infection. A total of 69 cellulase genes were retrieved within the Citrus sinensis genome, comprising 40 endoglucanase genes and 29 glucosidase genes. Transcriptomic analysis revealed that expression levels of CsCEL8, CsCEL9, CsCEL20, and CsCEL26 were induced by Xcc invasion in sweet orange leaves, but not in the resistant genotype Citron C-05. Among them, CsCEL20 exhibited the highest expression level, with an over 430-fold increase following Xcc infection. Additionally, RT-qPCR analysis confirmed that CsCEL20 expression was induced in susceptible genotypes (Sweet orange, Danna citron, Lemon) upon Xcc invasion, but not in resistant genotypes (Citron C-05, Aiguo citron, American citron). A Single-Nucleotide Polymorphism (SNP) at -423 bp was identified in the CEL20 promoters and exhibits a difference between eight susceptible citrus genotypes and three resistant ones. Moreover, CsCEL20 expression was upregulated in CsLOB1-overexpression transgenic lines compared to the wild type. Dual-luciferase reporter assays indicated that CsLOB1 can target the -505 bp to -168 bp region of CsCEL20 promoter to trans-activate its expression. These findings suggest that CsCEL20 may function as a candidate gene for citrus canker development and may be a promising target for biotechnological breeding of Xcc-resistant citrus genotypes.

Supplementary information: The online version contains supplementary material available at 10.1007/s11032-024-01531-3.

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纤维素酶基因CsCEL20在柑橘黄单胞菌感染中的作用。柑橘中的柑橘。

柑橘溃疡病是由柑橘黄单胞菌引起的一种破坏性疾病。citri （Xcc）分泌效应物PthA4进入寄主植物，触发易感基因CsLOB1的转录，导致脓包形成。然而，cslob1介导的Xcc易感性的分子机制尚不清楚。本研究发现CsCEL20是受CsLOB1正调控的靶基因。Xcc侵染后甜橙叶片细胞扩增，细胞壁降解。在柑橘基因组中共检索到69个纤维素酶基因，包括40个内切葡聚糖酶基因和29个葡萄糖苷酶基因。转录组学分析显示，CsCEL8、CsCEL9、CsCEL20和CsCEL26的表达水平在Xcc侵染的甜橙叶片中受到诱导，而在抗性基因型香橼C-05中不受影响。其中CsCEL20表达量最高，感染Xcc后表达量增加430倍以上。此外，RT-qPCR分析证实，在Xcc入侵时，CsCEL20在易感基因型（甜橙、丹纳香橼、柠檬）中被诱导表达，而在抗性基因型（香橼C-05、爱国者香橼、美洲香橼）中未被诱导表达。在CEL20启动子中发现了-423 bp的单核苷酸多态性（SNP），该多态性在8个易感柑橘基因型和3个抗性柑橘基因型之间存在差异。此外，与野生型相比，cslob1过表达转基因系中CsCEL20的表达上调。双荧光素酶报告基因实验表明，CsLOB1可以靶向CsCEL20启动子的-505 bp至-168 bp区域，以反式激活其表达。这些发现表明，CsCEL20可能是柑橘溃疡病发生的候选基因，可能是柑橘抗xcc基因型生物技术育种的一个有希望的靶点。补充资料：在线版本提供补充资料，网址为10.1007/s11032-024-01531-3。

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来源期刊

Molecular Breeding 农林科学-农艺学

CiteScore

5.60

自引率

6.50%

发文量

审稿时长

1.5 months

期刊介绍： Molecular Breeding is an international journal publishing papers on applications of plant molecular biology, i.e., research most likely leading to practical applications. The practical applications might relate to the Developing as well as the industrialised World and have demonstrable benefits for the seed industry, farmers, processing industry, the environment and the consumer. All papers published should contribute to the understanding and progress of modern plant breeding, encompassing the scientific disciplines of molecular biology, biochemistry, genetics, physiology, pathology, plant breeding, and ecology among others. Molecular Breeding welcomes the following categories of papers: full papers, short communications, papers describing novel methods and review papers. All submission will be subject to peer review ensuring the highest possible scientific quality standards. Molecular Breeding core areas: Molecular Breeding will consider manuscripts describing contemporary methods of molecular genetics and genomic analysis, structural and functional genomics in crops, proteomics and metabolic profiling, abiotic stress and field evaluation of transgenic crops containing particular traits. Manuscripts on marker assisted breeding are also of major interest, in particular novel approaches and new results of marker assisted breeding, QTL cloning, integration of conventional and marker assisted breeding, and QTL studies in crop plants.