Expression of WRKY Transcription Factor and Stress Protein Genes in Wheat Plants during Cold Hardening and ABA Treatment

Changes in expression of WRKY transcription factor and stress protein genes (Wcor15, Wrah17, Wrab19, and Wcs120) were studied on wheat (Triticum aestivum L., cv. Moskovskaya 39) seedlings exposed to cold hardening for 7 days at 4 degrees C. The high level of WRKY gene expression was noticed already in 15 min after the beginning of cold treatment, but the expression level lowered during longer treatments. Exogenous ABA (0.1 mM) suppressed the WRKY gene expression. The level of Wcor15 gene expression increased gradually, reaching the peak on the second day, and then decreased. Gene expression of Wrab17 remained elevated throughout the period of cold exposure (7 days), and expression of Wrab19 was promoted within the first two days. Exogenous ABA induced expression of Wcor15, Wrab17, and Wrab19 genes both at cold-hardening (4 degrees C) and normal (22 degrees C) temperatures. A significant increase in Wcs120 gene expression during cold hardening was ABA-independent. It is concluded that the increase of wheat plant resistance at the initial stage of cold hardening is related to gene expression of WRKY transcription factor and of stress proteins (Wcor15, Wrab17, Wrab19, and Wcs120), while the resistance increase during prolonged adaptation is related to gene expression of Wcor15 and Wrab17.