Expression characteristics of <i>CsESA1</i> in citrus and analysis of its interacting protein

The most damaging disease affecting citrus globally is Huanglongbing (HLB), primarily attributed to the infection by ‘<i>Candidatus Liberibacter</i> asiaticus’ (<i>Ca</i>Las). Based on comparative transcriptome data, two cellulose synthase (CESA) genes responsive to <i>Ca</i>Las infection induction were screened, and one gene cloned with higher differential expression level was selected and named <i>CsCESA1</i>. we verified the interaction between CsCESA1 and citrus exopolysaccharide 2 (CsEPS2) proteins. Subcellular localization in tobacco indicated that both CsCESA1 and CsEPS2 proteins are primarily located in the nucleus and cytoplasm. RT-qPCR analysis indicated that the expression levels of <i>CsCESA1</i> and <i>CsEPS2</i> were associated with variety tolerance, tissue site, and symptom development. Furthermore, we generated <i>CsCESA1</i> and <i>CsEPS2</i> silencing plants and obtained <i>CsCESA1</i> and <i>CsEPS2</i> silencing and overexpressing hairy roots. The analysis of hormone content and gene expression also showed that <i>CsCESA1</i> and <i>CsEPS2</i> are involved in transcriptional regulation of genes involved in systemic acquired resistance (SAR) response. In conclusion, our results suggested that <i>CsCESA1</i> and <i>CsEPS2</i> could serve as potential resistance genes for HLB disease, offering insights into the plant’s defense mechanisms against HLB.