Comprehensive Genomic Survey, Structural Classification, and Expression Analysis of WRKY Transcription Factor  Family in Rhododendron simsii

Abstract

(1) Rhododendron is one of the top ten traditional flowers in China, with both high ornamental and economic values. However, with the change of the environment, Rhododendron suffers from various biological stresses. The WRKY transcription factor is a member of the most crucial transcription factor families, which plays an essential regulatory role in a variety of physiological processes and developmental stresses. (2) In this study, 57 RsWRKYs were identified using genome data and found to be randomly distributed on 13 chromosomes. Based on gene structure and phylogenetic relationships, 57 proteins were divided into three groups: I, II, and III. Multiple alignments of RsWRKYs with Arabidopsis thaliana homologous genes revealed that WRKY domains in different groups had different conserved sites. RsWRKYs have a highly conserved domain, WRKYGQK, with three variants, WRKYGKK, WRKYGEK, and WRKYGRK. Furthermore, cis-acting elements analysis revealed that all of the RsWRKYs had stress and plant hormone cis-elements, with figures varying by group. Finally, the expression patterns of nine WRKY genes treated with gibberellin acid (GA), methyl jasmonate (MeJA), heat, and drought in Rhododendron were also measured using quantitative real-time PCR (qRT-PCR). The results showed that the expression levels of the majority of RsWRKY genes changed in response to multiple phytohormones and abiotic stressors. (3) This current study establishes a theoretical basis for future studies on the response of RsWRKY transcription factors to various hormone and abiotic stresses as well as a significant foundation for the breeding of new stress-tolerant Rhododendron varieties.

Genome-wide identification and bioinformatics analysis of the WRKY transcription factors and screening of candidate genes for anthocyanin biosynthesis in azalea (Rhododendron simsii)

“…We totally identified 57 RsWRKY gene members, which were further renamed as RsWRKY1 to RsWRKY57 according to their chromosomal positions on Chr1-13 and the order of scaffolds ( Table 1 ). The identification outcomes showed one gene that was different from the study by Wan et al (2022) . Our findings contain the RhsimUnG0199600 gene, while their findings include the Rhsim10G0148600 gene.…”

“…Compared with a previous study (Wan et al, 2022), a better phylogenetic analysis and grouping outcomes was achieved in our study. For instance, the previous research mixed two different clades into group III in phylogenetic tree, which results in a categorization error.…”

Development and application of the TRV-induced gene-silencing system in different Rhododendron species

“…Chen et al 2019; Sajjad et al 2021;Sun et al 2020). In recent years, molecular studies in terms of stress tolerance have also attained increasing attention in Rhododendron, such as WRKY transcription factors, which are crucial candidate genes in response to drought and high temperature(Wan et al 2022), most AP2 genes can respond to cold, salt and drought stresses(Guo et al 2023), key genes such as HSF, DREBs, ZATs and NACs determine heat tolerance(Fang et al 2017), and MADS-box candidate genes play signi cant roles in high temperature and waterlogging(Huo et al 2021). Therefore, the VIGS system in Rhododendron established in this study can be utilized to identify the function of key genes for stress tolerance and provide a solid foundation for improving stress tolerance.…”