Abstract：
Calcium (Ca2+) is a second messenger in various physiological processes within plants. The significance of the Ca2+/H+ exchanger (CAX) has been established in facilitating Ca2+ transport in plants; however, disease resistance functions of the CAX gene remain elusive. In this study, we conducted sequence characterization and expression analysis for a sugarcane CAX gene, ScCAX4 (GenBank Accession Number: MW206380). In order to further investigate the disease resistance functions, this gene was then transiently overexpressed in Nicotiana benthamiana leaves, which were subsequently inoculated with Fusarium solani var. coeruleum. Results showed that ScCAX4 overexpression increased the susceptibility of N. benthamiana to pathogen infection by regulating the expression of genes related to salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) pathways, suggesting its negative role in disease resistance. Furthermore, we genetically transformed the ScCAX4 gene into N. benthamiana and obtained three positive T2 generation lines. Interestingly, the symptomatology of transgenic plants was consistent with that of transient overexpression after pathogen inoculation. Notably, the JA content in transgenic overexpression lines was significantly higher than that in the wild-type. RNA-seq revealed that ScCAX4 could mediate multiple signaling pathways, and the JA signaling pathway played a key role in modulating disease resistance. Finally, a regulatory model was depicted for the increased susceptibility to pathogen infection conferred by the ScCAX4 gene. This study provides genetic resources for sugarcane molecular breeding and the research direction for plant CAX genes.
摘要：
钙（Ca2）是植物各种生理过程中的第二信使。Ca2+/H+交换剂(CAX)在促进植物中Ca2+运输方面的重要性已经确立；然而，CAX基因的抗病功能仍然难以捉摸。在这项研究中,我们对甘蔗CAX基因进行了序列鉴定和表达分析,ScCAX4（GenBank登录号：MW206380）。为了进一步研究其抗病功能,然后这个基因在烟草叶片中短暂过表达，随后接种了镰刀菌。蓝藻。结果表明,ScCAX4过表达通过调节水杨酸(SA)相关基因的表达,增加了对病原菌感染的易感性,茉莉酸（JA），和乙烯（ET）途径，提示其在抗病性中的负面作用。此外，我们将ScCAX4基因遗传转化到N.benthamiana中，并获得了三个阳性T2世代系。有趣的是,转基因植物的症状与病原体接种后的短暂过表达一致。值得注意的是,转基因过表达系的JA含量明显高于野生型。RNA-seq显示ScCAX4可以介导多种信号通路,JA信号通路在调节抗病性方面发挥了关键作用。最后,针对ScCAX4基因赋予的病原体感染易感性增加的调节模型进行了描述.本研究为甘蔗分子育种提供了遗传资源,为植物CAX基因的研究提供了方向。
