Abstract
Drought, salinity, and cold are the major factors limiting wheat quality and productivity; it is thus highly desirable to characterize the abiotic-stress-inducible promoters suitable for the genetic improvement of plant resistance. The sucrose non-fermenting 1-related protein kinase 2 (SnRK2) family genes show distinct regulatory properties in response to abiotic stresses. The present study characterized the approximately 3000-bp upstream sequence (the 313 bp upstream of the ATG was the transcription start site) of the Triticum aestivum TaSnRK2.8 promoter under abscisic acid (ABA) and abiotic stresses. Four different-length 5′ deletion fragments of TaSnRK2.8 promoter were fused with the GUS reporter gene and transformed into Arabidopsis. Tissue expression analysis showed that the TaSnRK2.8 promoter region from position -1481 to -821 contained the stalk-specific elements, and the region from position -2631 to -1481 contained the leaf- and root-specific elements. In the ABA-treated seedlings, the deletion analysis showed that the TaSnRK2.8 promoter region from position -821 to -2631 contained ABA response elements. The abiotic stress responses of the TaSnRK2.8 promoter derivatives demonstrated that they harbored abiotic-stress response elements: the region from position -821 to -408 harbored the osmotic-stress response elements, whereas the region from position -2631 to -1481 contained the positive regulatory motifs and the region from position -1481 to -821 contained the leaf- and stalk-specific enhancers. Further deletion analysis of the promoter region from position -821 to -408 indicated that a 125-bp region from position -693 to -568 was required to induce an osmotic-stress response. These results contribute to a better understanding of the molecular mechanisms of TaSnRK2.8 in response to abiotic stresses, and the TaSnRK2.8 promoter seems to be a candidate for regulating the expression of abiotic stress response genes in transgenic plants.
Highlights
Plant growth is adversely affected by abiotic stresses such as salinity, drought, and low temperature
Functional analysis of sucrose non-fermenting 1-related protein kinase 2 (SnRK2) genes indicated that the overexpression of TaSnRK2.3, TaSnRK2.4, TaSnRK2.7, or TaSnRK2.8 in Arabidopsis led to enhanced tolerance to abiotic stresses (Mao et al, 2009; Zhang et al, 2010, 2011; Tian et al, 2013)
Previous studies found that TaSnRK2.8 was strongly expressed in the roots, and faintly in the stems and leaves
Summary
Plant growth is adversely affected by abiotic stresses such as salinity, drought, and low temperature. The SnRK2 family is a plant-specific gene family that encodes serine/threonine kinases. It is divided into three distinct subclasses (I, II, and III) based on their functional divergence (Halford and Hardie, 1998). Except AtSnRK2.9, responded to drought and salt stresses, and none was induced by cold stress (Boudsocq et al, 2004, 2007). In rice, these 10 SnRK2 members, named SAPK1–10, were induced by osmotic stresses, and three (SAPK8–10) were induced by ABA treatment (Kobayashi et al, 2004). To date, little research has been conducted on the molecular mechanisms of SnRK2s in response to abiotic stress
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