CsBZIP40, a BZIP transcription factor in sweet orange, plays a positive regulatory role in citrus bacterial canker response and tolerance

Abstract

Citrus bacterial canker (CBC) caused by Xanthomonas citri subsp. citri (Xcc) is a systemic bacterial disease that affects citrus plantations globally. Biotic stress in plants has been linked to a group of important transcription factors known as Basic Leucine Zippers (BZIPs). In this study, CsBZIP40 was functionally characterized by expression analysis, including induction by Xcc and hormones, subcellular localization, over-expression and RNAi silencing. CsBZIP40 belongs to group D of the CsBZIP family of transcription factors and localizes in the nucleus, potentially serving as a transcriptional regulator. In wild type (WT) plants CsBZIP40 can be induced by plant hormones in addition to infection by Xcc which has given insight into its involvement in CBC. In the present study, over-expression of CsBZIP40 conferred resistance to Xcc while its silencing led to Xcc susceptibility. Both over-expression and RNAi affected salicylic acid (SA) production and expression of the genes involved in the SA synthesis and signaling pathway, in addition to interaction of CsBZIP40 with CsNPR1, as detected by a GST pull-down assay. Taken together, the results of this study confirmed the important role of CsBZIP40 in improving resistance to citrus canker through the SA signaling pathway by the presence of NPR1 to activate PR genes. Our findings are of potential value in the breeding of tolerance to CBC in citrus fruits.

Genome-Wide Analysis, Characterization, and Expression Profile of the Basic Leucine Zipper Transcription Factor Family in Pineapple

“…People also found that OsbZIP23 plays an important role in ABA signaling and biosynthesis in rice and overexpressed OsbZIP23 shows improved tolerance to salt and drought stress [21], and overexpression of the OsbZIP71 enhances tolerance to drought stress [22]. CsbZIP40 positively regulates SA synthesis, and the expression level of CsNPR1 was also regulated by CsbZIP40 expression in sweet orange [23].…”

Systematic Analysis and Functional Validation of Citrus Pectin Acetylesterases (CsPAEs) Reveals that CsPAE2 Negatively Regulates Citrus Bacterial Canker Development

“…When we assessed these three plants via qRT-PCR, we were able to confirm that they expressed significantly elevated CsPAE2 levels (29-fold, 36-fold, and 26-fold of WT, respectively) ( Figure 5 E). The acupuncture method is used to assess and compare the resistance between OE plants and WT [ 2 , 37 , 38 , 39 ]. We found that these OE plants exhibited much larger lesions and more significant symptoms relative to WT ( Figure 5 F).…”

“…Xcc inducible expression patterns of CsPAEs were measured as in prior reports [ 39 , 54 ]. Briefly, the mature new leaves (approximately 3-month-old leaves) of Calamondin and Wanjincheng (roughly 10-year-old plants) were picked and placed in the culture plates, while keeping the petioles wrapped in cotton that was soaked in ddH 2 O.…”

CitGVD: a comprehensive database of citrus genomic variations

“…Compared to previous databases designed to centralize species genomic variations, such as DoGSD for dog/wolves 16 and SorGSD for sorghum 17 , CitGVD is more powerful due to its combination of phenotypic data, genomic variations and in-depth analysis tools and pipelines which make evolutionary analysis and GWASs possible. Furthermore, CitGVD provides gene blast and annotation sections, which allow to annotate genes or gene families of Citrus species [30][31][32] . For rice, RiceVarMap 18 includes phenotypic data and GWASs that are similar to those in CitGVD.…”