Involvement of Dehydrins in the Response to Drought − Rakyat Biologi

The accumulation of dehydrins in plants is a common feature of the response to drought (Close, 1997). Earlier studies indicated that the accumulation of certain dehydrin proteins in seedlings was associated with drought tolerance in adult plants (Lopez et al., 2003). Overproduction of a wheat dehydrin (DHN5) in Arabidopsis enhanced the tolerance to osmotic stress. When compared to wild type plants, the dehydrin-5 transgenic plants exhibited stronger growth under water deprivation and more rapid recovery (Brini et al., 2007).

Some genes coding for mainly low-molecular weight and some alkaline YnSK-type dehydrins tend to be induced only by drought (Close et al., 2000). Recent results have confirmed that, under water deprivation, white clover synthesized an alternatively spliced Y₂SK transcript, which was absent after recovery of plant upon rehydration (Vaseva et al. 2011).

Two isoforms of YSK type dehydrin gene have been reported in expression studies of Vitis riparia and Vitis vinifera (Xiao and Nassuth 2006), and of winter wheat (Vaseva et al. 2010). Wheat WZY1-2 gene encodes a 262 amino acid alkaline YSK₂-type dehydrin with a predicted molecular weight of 28 kDa. It contains a serine-rich segment that can be phosphorylated and is thought to participate in nuclear localisation (Close, 1997). Quantitative differences in accumulation of WZY2 transcripts have been observed soon after withholding water, in winter wheat cultivars with different drought tolerance (Vaseva et al., 2010). The drought-tolerant variety showed a considerable increase in WZY2 transcript levels, accompanied by the presence of a second, high-density band, absent in the control samples. This alternatively spliced WZY2 transcript occurred only in drought-stressed plants and its expression levels were related to the drought-tolerance of the cultivars. The tolerant variety tends to accumulate WZY2 alternatively spliced transcripts earlier than the less tolerant ones. This makes WZY2 dehydrin a suitable candidate for a molecular marker of drought tolerance.