Role of the WRKY Gene Family in Dioscorea alata L. in Response to Nematode Stress Response and Hormonal Signal Regulation

doi:10.13560/j.cnki.biotech.bull.1985.2025-1287

Abstract

Abstract:

Objective Systematic identification and characterization of WRKY gene family members in greater yam (Dioscorea alata) were performed to establish a foundation for subsequent research on their functions in response to root-knot nematode stress. Method Based on the whole-genome data of Dioscorea alata, we conducted a genome-wide identification of the DaWRKY gene family using bioinformatics methods. The analyses included physicochemical properties of the encoded proteins, phylogenetic relationships, gene structures, chromosomal locations, and promoter cis-acting elements. The expression patterns of the DaWRKY gene were analyzed using a combined approach of transcriptome data and RT-qPCR experiments across various tissues, under Meloidogyne incognita stress, and in response to treatments with plant hormones (ABA, MeJA, and SA). Result A total of 70 DaWRKY genes were identified in D. alata. The encoded proteins, ranging from 127 to 651 amino acids in length, were all predicted to be hydrophilic and localized to the nucleus. Phylogenetic analysis classified them into three groups (I, II, and III), with group II being the largest proportion (65.71%). Chromosomal location analysis revealed that these genes were unevenly distributed across 15 chromosomes. Expression profile analysis indicated that DaWRKY genes were significantly enriched in roots and microtubers. Under M. incognita stress, eight DaWRKY genes were up-regulated at 7 d post-infection, among which DaWRKY2 exhibited the highest fold change in up-regulation. During ABA treatment, only DaWRKY33 was down-regulated from 1 to 5 d, while DaWRKY26 showed the most significant up-regulation. JA treatment induced an initial decrease followed by an increase in the expression of DaWRKY33 and DaWRKY69, and eight genes were all up-regulated at 12 h post-treatment. Under SA treatment, all genes except DaWRKY16 were up-regulated at 12 h. Conclusion A total of 70 DaWRKY transcription factors were identified in D. alata. Among them, members such as DaWRKY2, DaWRKY33, and DaWRKY46 showed significant responses to root-knot nematode infection as well as treatment with defense-related hormones including ABA, JA, and SA. These results indicate that the DaWRKY gene family plays crucial roles in the response of D. alata to biotic and abiotic stresses, providing a foundation for elucidating the stress resistance mechanisms of this crop.

Key words: Dioscorea alata, WRKY gene family, transcription factor, nematode stress, hormone induction, gene expression

WANG Ming-zhu, SUN Lin-tao, CHANG Ying-ying, ZHANG Jiang-li, GAO Jin, WANG Rui-fei, ZHANG Hao, LI Ming-jun, YANG Qing-xiang. Role of the WRKY Gene Family in Dioscorea alata L. in Response to Nematode Stress Response and Hormonal Signal Regulation[J]. Biotechnology Bulletin, doi: 10.13560/j.cnki.biotech.bull.1985.2025-1287.

Figures/Tables 8

Fig. 1 Phylogenetic tree of WRKY gene family in D. alata and A. thaliana

Fig. 2 Motif distribution (A), conserved domain (B), and gene structure (C) analysis of DaWRKYFor typesetting purposes, longer genes have been partially truncated (indicated by \). The schematic diagram only shows the relative positions of motifs, domains, and CDS regions, and does not indicate their absolute locations in the gene or protein

Fig. 3 Analysis of the cis-acting elements of the DaWRKY geneThe central panel is a heatmap displaying the enrichment levels of cis-acting elements. The stacked bar chart on the right illustrates the abundance of cis-acting elements: blue rectangles represent light-responsive cis-acting elements; green rectangles, hormone-responsive cis-elements; yellow rectangles, stress-responsive cis-elements; while cyan rectangles denote cis-elements associated with growth and development

Fig. 4 Chromosomal location (A) and collinearity analysis (B) of DaWRKY gene family in D. alataA: Colored rectangular bars represent the chromosomes of D. alata; Chr1-20 indicate the corresponding chromosomes; the red thick outlines indicate gene tandem duplications, and the scale bar of 0-40 Mb represents the chromosome length. B: Red lines indicate segmental duplications, and the two genes connected by red lines are homologous. Gene density is represented by heatmap (inner circle), the outer circle shows the chromosome length, and the black line segments on the outermost circle indicate the gene locations on the chromosomes

Fig. 5 The collinearity analysis of WRKY genes in D. alata, D. rotundata, O. sativa, and A. thaliana

Fig. 6 Relative expression of DaWRKY in different tissuesDifferent lowercase letters indicate significant differences among groups (P<0.05). The same below

Fig. 7 Relative expression of DaWRKY genes at different stages after M. incognita inoculation

Fig. 8 Relative expression of the DaWRKY gene at different time under various hormonal treatmentsA: Treatment with ABA. B: Treatment with MeJA. C: Treatment with SA

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