Identification and expression of the WRKY transcription factors of Carica papaya in response to abiotic and biotic stresses

The WRKY transcription factor (TF) plays a very important role in the response of plants to various abiotic and biotic stresses. A local papaya database was built according to the GenBank expressed sequence tag database using the BioEdit software. Fifty-two coding sequences of Carica papaya WRKY TFs were predicted using the tBLASTn tool. The phylogenetic tree of the WRKY proteins was classified. The expression profiles of 13 selected C. papaya WRKY TF genes under stress induction were constructed by quantitative real-time polymerase chain reaction. The expression levels of these WRKY genes in response to 3 abiotic and 2 biotic stresses were evaluated. TF(807.3) and TF(72.14) are upregulated by low temperature; TF(807.3), TF(43.76), TF(12.199) and TF(12.62) are involved in the response to drought stress; TF(9.35), TF(18.51), TF(72.14) and TF(12.199) is involved in response to wound; TF(12.199), TF(807.3), TF(21.156) and TF(18.51) was induced by PRSV pathogen; TF(72.14) and TF(43.76) are upregulated by SA. The regulated expression levels of above eight genes normalized against housekeeping gene actin were significant at probability of 0.01 levels. These WRKY TFs could be related to corresponding stress resistance and selected as the candidate genes, especially, the two genes TF(807.3) and TF(12.199), which were regulated notably by four stresses respectively. This study may provide useful information and candidate genes for the development of transgenic stress tolerant papaya varieties. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11033-013-2966-8) contains supplementary material, which is available to authorized users.