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Osmotic stress is affecting crop growth, development and production of one of the most serious abiotic stress. For a long time, improve crops for osmotic stress resistance has always been the efforts goal of breeding scientists. However, due to osmotic stress response is a very complicated process, through conventional breeding success is very limited. In recent years, due to the development of molecular biology and osmotic stress related genes found ceaselessly, molecular mechanism of plant osmotic stress resistance has a deeper understanding, which people laid a foundation for genetic engineering of plant osmotic stress resistance (Jie Li, Lihua & Chen, Yanming, 2005).
Some studies have reported that osmotic stress inhibits the growth of crops (Deguang Yang, Yongxi Liu, & Qian Zhang, 2015; Munns R, 2002). As found in wheat research, osmotic stress decreased the relative water content of wheat seedlings, inhibited the growth of seedlings (Lei, Yin & Ren, 2007). In the research of Phaseolus found that osmotic stress can inhibit the accumulation of dry matter and quality, resulting in destruction of chlorophyll components, leaves changed yellow, and the photosynthetic efficiency decreased. It was also found that the inhibition to the stem being more intense than the root suffered (Aydi, Aydi & Gonzalez, 2008). In addition, osmotic stress destroyed the balance of active oxygen metabolism, which resulted in oxidative stress. In the experiment of tomato, it was found that the excessive reactive oxygen species could cause oxidative damage to tomato leaves (Nasibi & Kalantari, 2009). Under osmotic stress, the increase of superoxide radical can induce ethylene biosynthesis in mung bean (Ke & Sun, 2004). The results showed that superoxide radicals could be used as catalysts for the conversion aminocyclopropane carboxylic acid to ethylene, which resulted in the increase of ethylene content and finally resulted the aging of pea seeds.
Abiotic stresses seriously affect plant growth and development, reduce crop yields. Plant have a variety of ways to resist or tolerate abiotic stress, mainly is the expression of a variety of abiotic stress resistance gene. Gene expression is regulated by its promoter and transcription factors, the current study of abiotic stress-inducible promoter cis-acting elements and transcription factors has become a hot issue (Guo, Zhan, & Yang, 2015). Many plant gene expressions are subject to the stress induced by stress, stress resistance gene expression is to rely on its upstream promoter regulation to achieve. Figure 1 shows the specific process of induction of genes by abiotic stress.
Higher plants promoter belongs to the type II promoter, different type of promoter has a relatively conserved sequence block, between closely related species, the promoter has some versatility, so using Arabidopsis as experimental model crop to with the phylogenetic relationships of plants of the same genome mining is feasible (Stockinger & Gilmour, 1997).
Many biology experts through the biological experiment of osmotic stress response genes in higher plants to forecast and digging, part shown in the Table 1.
In addition, the drought can induce hypothermia in Arabidopsis CBF1 (JASMONATE,2008)and DREB1 / 2 gene (Guo, He & Liu, 2005), JAZ family genes (Guo, Jiao & Di, 2009), JERF gene (Xie, Zhang & Zou, 2005), WRKY gene (Eulgem & Somssich, 2007; Zheng, Guo & Zhang, 2011) and MYB gene (Xu, Zhang & Wangang, 2006).