Abstract
Dehydration-responsive element-binding protein 1 (DREB1)/C-repeat binding factor (CBF) family plays a key role in plant tolerance against different abiotic stresses. In this study, an orthologous gene of the DWARF AND DELAYED FLOWERING (DDF) members in Arabidopsis, SlDDF2, was identified in tomato plants. The SlDDF2 gene expression was analyzed, and a clear induction in response to ABA treatment, cold, salinity, and drought stresses was observed. Furthermore, two transgenic lines (SlDDF2-IOE#6 and SlDDF2-IOE#9) with stress-inducible overexpression of SlDDF2 under Rd29a promoter were generated. Under stress conditions, the gene expression of SlDDF2 was significantly higher in both transgenic lines. The growth performance, as well as physiological parameters, were evaluated in wild-type and transgenic plants. The transgenic lines showed growth retardation phenotypes and had higher chlorophyll content under stress conditions in plants. However, the relative decrease in growth performance (plant height, leaf number, and leaf area) in stressed transgenic lines was lower than that in stressed wild-type plants, compared with nonstressed conditions. The reduction in the relative water content and water loss rate was also lower in the transgenic lines. Compared with wild-type plants, transgenic lines showed enhanced tolerance to different abiotic stresses including water deficit, salinity, and cold. In conclusion, stress-inducible expression of SlDDF2 can be a useful tool to improve tolerance against multiple abiotic stresses in tomato plants.
Highlights
Abiotic stresses, such as cold, drought, high salinity, and extreme heat have adverse effects on plant growth and development
To identify DELAYED FLOWERING (DDF) orthologous gene in tomato plants, a TBLASTN search was conducted against the annotated ITAG2.3 predicted tomato cDNA sequences database using the full-length amino acids sequence data of the DDF1 gene from Arabidopsis
Subfamily proteins from tomato and Arabidopsis belonging to groups DREB-A1 and DREBA2 revealed the identity of SlDDF proteins, which clustered with DDF1 and DDF2 proteins from Arabidopsis (Figure 1)
Summary
Abiotic stresses, such as cold, drought, high salinity, and extreme heat have adverse effects on plant growth and development. They are considered major constraints for plant production in many areas around the globe. To minimize the negative impact of abiotic stresses on plants, it is necessary to develop new plants that utilize water more efficiently and tolerate such stresses [1]. In this perspective, a basic strategy is based on the cloning of key regulatory genes and the introduction of their active forms into plants so that they can acquire abiotic stress tolerance phenotypes [2]. Plants have developed different defense mechanisms against abiotic stresses that involve the interaction among a group
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