WRKY transcription factors are known to play important roles in the regulation of various aspects of plant growth and development, including germination, stress resistance, and senescence. Nevertheless, there is little information about the WRKY genes in Hibiscus hamabo Sieb. et Zucc., an important semimangrove plant. In this study, HhWRKY genes in H. hamabo were identificated based on Illumina RNA-sequencing and isoform sequencing from salt-treated roots. Then phylogenetic analysis and conserved motif analysis of the WRKY family in H. hamabo and Arabidopsis thaliana were used to classify WRKY genes. Sixteen HhWRKY genes were selected from different groups to detect their expression patterns using real-time quantitative PCR in different organ (root, old leaf, tender leaf, receptacle, petal, or stamen) from 10-year-old H. hamabo plants grown in their natural environment and in seedlings with 8 to 10 true leaves challenged by phytohormone (salicylic acid, methyl jasmonate, or abscisic acid) and abiotic stress (drought, salt, or high temperature). As a result, the identified 78 HhWRKY genes were divided into two major groups and several subgroups based on their structural and phylogenetic features. Most transcripts of the selected 16 HhWRKY genes were more abundant in old than in tender leaves of H. hamabo. HhWRKY genes were regulated in reaction to abiotic stresses and phytohormone treatments and may participate in signaling networks to improve plant stress resistance. Some of HhWRKY genes behaved as would be predicted based on their homology with A. thaliana WRKY genes, but others showed divergent behavior. This systematic analysis lays the foundation for further identification of WRKY gene functions, with the aim of improving woody plants.
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References
1.
BaiY., WuD., LiuF., LiY., ChenP., LuM., et al. (2017). Characterization and functional analysis of the poplar Pectate Lyase-like gene PtPL1–18 reveal its role in the development of vascular tissues. Front Plant Sci 8,1123.
2.
BaileyT.L., WilliamsN., MislehC., and LiW.W. (2006). MEME: discovering and analyzing DNA and protein sequence motifs. Nucleic Acids Res, 34, W369–W373.
3.
BanerjeeA., and RoychoudhuryA. (2015). WRKY proteins: signaling and regulation of expression during abiotic stress responses. ScientificWorldJournal 2015,807560.
4.
BrandL.H., FischerN.M., HarterK., KohlbacherO., and WankeD. (2013). Elucidating the evolutionary conserved DNA-binding specificities of WRKY transcription factors by molecular dynamics and in vitro binding assays. Nucleic Acids Res, 41, 9764–9778.
5.
ChenL., YuS., LiS., ZhangL., ZouC., and YuD. (2012). The role of WRKY transcription factors in plant abiotic stresses. Biochim Biophys Acta, 1819, 120–128.
6.
DevaiahB.N., KarthikeyanA.S., and RaghothamaK.G. (2007). WRKY75 transcription factor is a modulator of phosphate acquisition and root development in Arabidopsis. Plant Physiol, 143, 1789–1801.
7.
EulgemT., RushtonP.J., RobatzekS., and SomssichI.E. (2000). The WRKY superfamily of plant transcription factors. Trends Plant Sci, 5, 199–206.
8.
HeC., JaT.D.S., TanJ., ZhangJ., PanX., LiM., et al. (2017). A genome-wide identification of the WRKY family genes and a survey of potential WRKY target genes in Dendrobium officinale. Sci Rep 7,9200.
9.
HeX., LiJ.J., ChenY., YangJ.Q., and ChenX.Y. (2019). Genome-wide analysis of the WRKY gene family and its response to abiotic stress in buckwheat (Fagopyrum tataricum). Open Life Sci, 14, 80–96.
10.
HinderhoferK., and ZentgrafU. (2001). Identification of a transcription factor specifically expressed at the onset of leaf senescence. Planta, 213, 469–473.
11.
HuangY., FengC.Z., YeQ., WuW.H., and ChenY.F. (2016). Arabidopsis WRKY6 transcription factor acts as a positive regulator of abscisic acid signaling during seed germination and early seedling development. PLoS Genet 12,e1005833.
12.
IshiguroS., and NakamuraK. (1994). Characterization of a cDNA encoding a novel DNA-binding protein, SPF1, that recognizes SP8 sequences in the 5′ upstream regions of genes coding for sporamin and β-amylase from sweet potato. Mol Gen Genet, 244, 563–571.
13.
JiangY., and DeyholosM. (2009). Functional characterization of Arabidopsis NaCl-inducible WRKY25 and WRKY33 transcription factors in abiotic stresses. Plant Mol Biol, 69, 91–105.
14.
JiangY.J., and DiqiuY.U. (2015). WRKY transcription factors: links between phytohormones and plant processes. Sci China Life Sci 58,501.
15.
JiangJ., MaS., YeN., JiangM., CaoJ., and ZhangJ. (2016). WRKY transcription factors in plant responses to stresses. J Integr Plant Biol 59,86.
16.
JoshiR., WaniS.H., SinghB., BohraA., DarZ.A., LoneA.A., et al. (2016). Transcription factors and plants response to drought stress: current understanding and future directions. Front Plant Sci 7,1029.
17.
KaranjaB.K., FanL., XuL., WangY., ZhuX., TangM., et al. (2017). Genome-wide characterization of the WRKY gene family in radish (Raphanus sativus L.) reveals its critical functions under different abiotic stresses. Plant Cell Rep, 36, 1–17.
18.
KumarS., StecherG., and TamuraK. (2016). MEGA7: molecular evolutionary genetics analysis version 7.0 for bigger datasets. Mol Biol Evol 33,1870.
19.
LangfelderP., and HorvathS. (2008). WGCNA: an R package for weighted correlation network analysis. BMC Bioinformatics 9,559.
20.
LiD., LiuP., YuJ., WangL., DossaK., ZhangY., et al. (2017a). Genome-wide analysis of WRKY gene family in the sesame genome and identification of the WRKY genes involved in responses to abiotic stresses. BMC Plant Biol 17,152.
21.
LiJ., LiaoJ., GuanM., WangE., and ZhangJ. (2012). Salt tolerance of Hibiscus hamabo seedlings: a candidate halophyte for reclamation areas. Acta Physiol Plant, 34, 1747–1755.
22.
LiL., MuS., ChengZ., ChengY., ZhangY., MiaoY., et al. (2017b). Characterization and expression analysis of the WRKY gene family in moso bamboo. Sci Rep 7,6675.
23.
LiW., WangH., and YuD. (2016). Arabidopsis WRKY transcription factors WRKY12 and WRKY13 oppositely regulate flowering under short-day conditions. Mol Plant, 9, 1492–1503.
24.
LiaoY.L., XuF., ZangW.W., ChengS.Y., ShenY.B., and ChangJ. (2016). Cloning, characterization and expression analysis of GbWRKY11, a novel transcription factor gene in Ginkgo biloba. Int J Agric Biol, 18, 117–124.
25.
LiuQ.N., LiuY., XinZ.Z., ZhangD.Z., GeB.M., YangR.P., et al. (2017). Genome-wide identification and characterization of the WRKY gene family in potato (Solanum tuberosum). Biochem Syst Ecol, 71, 212–218.
26.
MiaoY., LaunT., ZimmermannP., and ZentgrafU. (2004). Targets of the WRKY53 transcription factor and its role during leaf senescence in Arabidopsis. Plant Mol Biol, 55, 853–867.
27.
NiL., WangZ., LiuL., GuoJ., LiH., and GuC. (2019). Selection and verification of candidate reference genes for gene expression by quantitative RT-PCR in Hibiscus hamaboSieb.et Zucc. Trees 31,1591.
28.
PhukanU.J., JeenaG.S., and ShuklaR.K. (2016). WRKY transcriptionfactors: molecular regulation and stress responses in plants. Front Plant Sci 7,760.
29.
PnueliL., Hallak-HerrE., RozenbergM., CohenM., GoloubinoffP., KaplanA., et al. (2002). Molecular and biochemical mechanisms associated with dormancy and drought tolerance in the desert legume Retama raetam. Plant J, 31, 319–330.
30.
RadićS., Radić-StojkovićM., and Pevalek-KozlinaB. (2006). Influence of NaCl and mannitol on peroxidase activity and lipid peroxidation in Centaurea ragusina L. roots and shoots. J Plant Physiol, 163, 1284–1292.
31.
RobatzekS., and SomssichI.E. (2010). A new member of the Arabidopsis WRKY transcription factor family, AtWRKY6, is associated with both senescence- and defence-related processes. Plant J, 28, 123–133.
SchluttenhoferC., and YuanL. (2015). Regulation of specialized metabolism by WRKY transcription factors. Plant Physiol, 167, 295–306.
34.
ShenH. (2007). A preliminary study on the molecular mechanism of WRKY family in regulating plant stress resistance signaling pathway (Fudan University, Shanghai).
35.
SilkeR., and SomssichI.E. (2002). Targets of AtWRKY6 regulation during plant senescence and pathogen defense. Genes Dev, 16, 1139–1149.
36.
SongA., LiP., JiangJ., ChenS., LiH., ZengJ., et al. (2014). Phylogenetic and transcription analysis of chrysanthemum WRKY transcription factors. Int J Mol Sci, 15, 14442–14455.
37.
SunX.-L., YuQ.-Y., TangL.-L., JiW., BaiX., CaiH., et al. (2013). GsSRK, a G-type lectin S-receptor-like serine/threonine protein kinase, is a positive regulator of plant tolerance to salt stress. J Plant Physiol, 170, 505–515.
38.
WangF., HouX., TangJ., WangZ., WangS., JiangF., et al. (2012a). A novel cold-inducible gene from Pak-choi (Brassica campestris ssp chinensis), BcWRKY46, enhances the cold, salt and dehydration stress tolerance in transgenic tobacco. Mol Biol Rep, 39, 4553–4564.
39.
WangX., SunH., LiuY., ChenY., FengD., and LiS. (2012b). Effects of treating with concentrated sulfuric acid on the seed germination of ten Hibiscus hamabo provenance families. Chin J Appl Ecol, 23, 2968–2974.
40.
WangZ., XuX., NiL., GuoJ., and GuC. (2019). Efficient virus-induced gene silencing in Hibiscus hamabo Sieb. et Zucc. using Tobacco rattle virus. PeerJ 7,e7505.
41.
WuJ., ChenJ., WangL., and WangS. (2017). Genome-wide investigation of WRKY transcription factors involved in terminal drought stress response in common bean. Front Plant Sci 8,380.
42.
XiaoY., ZhouL., LeiX., CaoH., WangY., DouY., et al. (2017). Genome-wide identification of WRKY genes and their expression profiles under different abiotic stresses in Elaeis guineensis. PLoS One 12,e0189224.
43.
XieT., ChenC., LiC., LiuJ., LiuC., and HeY. (2018). Genome-wide investigation of WRKY gene family in pineapple: evolution and expression profiles during development and stress. BMC Genomics 19,490.
44.
XueC., LiH., LiuZ., WangL., ZhaoY., WeiX., et al. (2019). Genome-wide analysis of the WRKY gene family and their positive responses to phytoplasma invasion in Chinese jujube. BMC Genomics 20,464.
45.
YanH. (2013). GhWRKY17, a WRKY Transcription Factor from Cotton (Gossypium hirsutum L.) Is Involved in aba Signaling and Drought, Salt Stress Response. (Shandong Agricultural, University, Taian).
46.
YanY., YuanZ., ChiY., FanB., and ChenZ. (2017). Characterization of soybean WRKY gene family and identification of soybean WRKY genes that promote resistance to soybean cyst nematode. Sci Rep 7,17804.
47.
YangG., WangC., WangY., GuoY., ZhaoY., YangC., et al. (2016). Overexpression of ThVHAc1 and its potential upstream regulator, ThWRKY7, improved plant tolerance of cadmium stress. Sci Rep 6,18752.
48.
ZhangY., and WangL. (2005). The WRKY transcription factor superfamily: its origin in eukaryotes and expansion in plants. BMC Evol Biol 5,1.
49.
ZhangZ.L., XieZ., ZouX., CasarettoJ., HoT.D., and ShenQ.J. (2004). A rice WRKY gene encodes a transcriptional repressor of the gibberellin signaling pathway in aleurone cells. Plant Physiol, 134, 1500–1513.
50.
ZhaoP., WangD., WangR., KongN., ZhangC., YangC., et al. (2018). Genome-wide analysis of the potato Hsp20 gene family: identification, genomic organization and expression profiles in response to heat stress. BMC Genomics 19,61.
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