Study on salt tolerance with YHem1 transgenic canola (Brassica napus)

Abstract

5-Aminolevulinic acid (5-ALA) has been suggested for improving plant salt tolerance via exogenous application. In this study, we used a transgenic canola (Brassica napus), which contained a constituted gene YHem1 and biosynthesized more 5-ALA, to study salt stress responses. In a long-term pot experiment, the transgenic plants produced higher yield under 200 mmol L(-1) NaCl treatment than the wild type (WT). In a short-term experiment, the YHem1 transformation accelerated endogenous 5-ALA metabolism, leading to more chlorophyll accumulation, higher diurnal photosynthetic rates and upregulated expression of the gene encoding Rubisco small subunit. Furthermore, the activities of antioxidant enzymes, including superoxide dismutase, guaiacol peroxidase, catalase and ascorbate peroxidase, were significantly higher in the transgenic plants than the WT, while the levels of O2 ·(-) and malondialdehyde were lower than the latter. Additionally, the Na(+) content was higher in the transgenic leaves than that in the WT under salinity, but K(+) and Cl(-) were significantly lower. The levels of N, P, Cu, and S in the transgenic plants were also significantly lower than those in the WT, but the Fe content was significantly improved. As the leaf Fe content was decreased by salinity, it was suggested that the stronger salt tolerance of the transgenic plants was related to the higher Fe acquisition. Lastly, YHem1 transformation improved the leaf proline content, but salinity decreased rather than increased it. The content of free amino acids and soluble sugars was similarly decreased as salinity increased, but it was higher in the transgenic plants than that in the WT.

Hydrogen peroxide as a mediator of 5‐aminolevulinic acid‐induced Na+ retention in roots for improving salt tolerance of strawberries

“…Then, the beneficial effect was confirmed in many other species, such as spinach (Nishihara et al ), pak choi (Wang et al ), potato (Zhang et al ), date palm (Youssef and Awad ), sunflower (Akram et al ), Swiss chard (Liu et al ), creeping bentgrass (Yang et al ), watermelon (Chen et al ), strawberry (Wu et al ), Brassica napus L. (Xiong et al ) and asparagus (Al‐Ghamdi and Elansary ). In transgenic plants, excessive biosynthesis of endogenous ALA can also improve salt tolerance in Arabidopsis (Zhang et al ), tomato (Li et al ) and canola (Sun et al ). Thus, the hypothesis that ALA improves salt tolerance in plants is supported by physiological and genetic evidence.…”

“…This hypothesis has been supported by many reports (Akram and Ashraf , Yang et al ). However, in transgenic tomatoes (Li et al ) and canola (Sun et al ), which over‐produce endogenous ALA, strong salt tolerance is always associated with higher H 2 O 2 . Miller et al () reported that Arabidopsis mutants lacking the cytosolic and/or chloroplastic H 2 O 2 ‐removal enzyme ascorbate peroxidase, were more salt tolerant.…”

Molecular response of canola to salt stress: insights on tolerance mechanisms

“…According to these results, transgenic plants are able to survive under the salinity level in which wild-type plants are more sensitive ( Shafeinie et al., 2014 ). Given that 5-Aminolevulinic acid (5-ALA) exogenous application resulted in salt tolerance in treated plants, Sun et al. (2015) transformed canola with 5-ALA-encoding gene, YHem1, and studied the growth of the transgenic canola capable to synthesize more 5-ALA, and wild-type canola under salinity stress.…”

5-Aminolevulinic Acid-induced Salt Tolerance in Strawberry: Possible Role of Nitric Oxide on Interception of Salty Ions in Roots

“…6B). In a transgenic canola (Brassica napus) which can over-produce endogenous ALA, the leaf Clcontent is strictly limited to a very low level, even seedlings were stressed by 450 mM NaCl [51]. Additionally, in the previous study when the ion levels of xylem sap was measured, it was also found that ALA signi cantly depressed [Cl -] xylem under salt stress, which were 2.39, 6.20 and 3.50 μmol L -1 in the control, NaCl stress and NaCl + ALA, respectively.…”