Effects of abscisic acid treatment on the expression of cysteine proteinase gene and enzyme inhibitor during wheat cold adaptation

Abstract

The effects of exogenous ABA on the expression of the cysteine proteinase (CP) gene and its inhibitor cystatin (WC3) in the leaves of winter wheat (Triticum aestivum L.) seedlings that were hardened for 7 days at 5°C were studied. Seedling cold-hardiness was judged by the temperature causing death of 50% of palisade cells (LT50) following 5-min freezing at the temperatures from −5 to −10°C. In the initial period of cooling, when seedling cold tolerance increased, the CP and WC3 gene expression increased considerably, but at the highest cold-hardiness the transcript levels of these genes returned to the control level. When ABA was applied exogenously, the CP gene expression grew by the order of magnitude already in 1–5 h from the onset of low temperature treatment and then abruptly dropped, but it was further maintained at a high level. In cold- and ABA-treated seedlings, the WC3 gene expression initially decreased, but it grew considerably in 3–7 days. It is concluded that the development of wheat cold-hardiness is related to ABA-regulated changes in the CP and WC3 gene expression.