The transcription factor WRKY family is one type of key regulatory components of plant development and defense against stress factors. The expression profiles of three AtWRKY genes under abiotic stresses were analyzed by Northern blotting analysis. The expression of AtWRKY25, AtWRKY26, and AtWRKY33 changed during stress treatments including thermal factors, NaCl, abscisic acid (ABA) and osmotic stress, and significantly under NaCl and cold treatments, suggesting a specific role of the three AtWRKYs in adaptation to environmental stresses in plants. We also found that the three AtWRKY genes showed distinct expression patterns under thermal stresses. AtWRKY25 and AtWRKY26 were gradually induced during heat and cold treatments, whereas AtWRKY33 was suppressed by heat treatment and induced rapidly during cold stress, indicating that the three AtWRKYs may play different roles in response to temperature factors. In addition, we analyzed the sequence of the promoters with bioinformatics approach, and some cis-elements involved in abiotic stresses and hormonal responses were revealed. The results provided important information for studying biological functions of three AtWRKY genes.
[1] Zhu JK. Cell signaling under salt, water and cold stresses. Curr Opin Plant Biol, 2001, 4(5): 401–406.
[2] Seki M, Kamei A, Yamaguchi-Shinozaki K, Shinozaki K. Molecular responses to dehydration, salinity and frost: common and different paths for plant protection. Curr Opin Biotechnol, 2003, 14(2): 194–199.
[3] Clarke SM, Mur LA, Wood JE, Scott IM. Salicylic acid dependent signaling promotes basal thermotolerance but is not essential for acquired thermotolerance in Arabidopsis thaliana. Plant J, 2004, 38(3): 432–447.
[4] Yu D, Chen C, Chen Z. Evidence for an important role of WRKY DNA binding proteins in the regulation of NPR1 gene expression. Plant Cell, 2001, 13(7): 1527–1540.
[5] Asai T, Tena G, Plotnikova J, Willmann MR, Chiu WL, Gomez-Gomez L, Boller T, Ausubel FM, Sheen J. MAP kinase signaling cascade in Arabidopsis innate immunity. Nature, 2002, 415(6875): 977–983.
[6] Johnson CS, Kolevski B, Smyth DR. TRANSPARENT TESTA GLABRA2, a trichome and seed coat develop-ment gene of Arabidopsis, encodes a WRKY transcription factor. Plant Cell, 2002, 14(6): 1359–1375.
[7] Luo M, Dennis ES, Berger F, Peacock WJ, Chaudhury A. MINISEED3 (MINI3), a WRKY family gene, and HAIKU2 (IKU2), a leucine-rich repeat (LRR) KINASE gene, are regulators of seed size in Arabidopsis. Proc Natl Acad Sci USA, 2005, 102(48): 17531–17536.
[8] Robatzek S, Somssich IE. Targets of AtWRKY6 regula-tion during plant senescence and pathogen defense. Genes Dev, 2002, 16(9): 1139–1149.
[9] Zhou QY, Tian AG, Zou HF, Xie ZM, Lei G, Huang J, Wang CM, Wang HW, Zhang JS, Chen SY. Soybean WRKY-type transcription factor genes, GmWRKY13, GmWRKY21, and GmWRKY54, confer differential tol-erance to abiotic stresses in transgenic Arabidopsis plants. Plant Biotechnol J, 2008, 6(5): 486–503.
[10] Fowler S, Thomashow MF. Arabidopsis transcriptome profiling indicates that multiple regulatory pathways are activated during cold acclimation in addition to the CBF cold response pathway. Plant Cell, 2002, 14(8): 1675–1690.
[11] Ramamoorthy R, Jiang SY, Kumar N, Venkatesh PN, Ramachandran S. A comprehensive transcriptional profil-ing of the WRKY gene family in rice under various abiotic and phytohormone treatments. Plant Cell Physiol, 2008, 49(6): 865-879.
[12] Wu X, Shiroto Y, Kishitani S, Ito Y, Toriyama K. En-hanced heat and drought tolerance in transgenic rice seed-lings overexpressing OsWRKY11 under the control of HSP101 promoter. Plant Cell Rep, 2009, 28(1): 21–30.
[13] Qiu Y, Yu D. Over-expression of the stress-induced Os-WRKY45 enhances disease resistance and drought toler-ance in Arabidopsis. Environ Exp Bot, 2009, 65(1): 35–47.
[14] Wei W, Zhang YX, Han L, Guan ZQ, Chai TY. A novel WRKY transcriptional factor from Thlaspi caerulescens negatively regulates the osmotic stress tolerance of trans-genic tobacco. Plant Cell Rep, 2008, 27(4): 795–803.
[15] Sanchez-Ballesta MT, Lluch Y, Gosalbes MJ, Zacarias L, Granell A, Lafuente MT. A survey of genes differentially expressed during long-term heat induced chilling tolerance in citrus fruit. Planta, 2003, 218(1): 65–70.
[16] Zou X, Seemann JR, Nemnan D, Shen QJ. A WRKY gene from creosote bush encodes an activator of the abscisic acid signal-ing pathway. J Biol Chem, 2004, 279(53): 55770–55779.
[17] Dong J, Chen C, Chen Z. Expression profiles of the Arabidopsis WRKY gene superfamily during plant defense response. Plant Mol Biol, 2003, 51(1): 21–37.
[18] Ülker B, Somssich IE. WRKY transcription factors: from DNA binding towards biological function. Curr Opin Plant Biol, 2004, 7(5): 491–498.
[19] Andreasson E, Jenkins T, Brodersen P, Thorgrimsen S, Petersen NHT, Zhu SJ, Qiu JL, Micheelsen P, Rocher A, Petersen M, Newman MA,
