Abstract
Rapeseed (Brassica napus L.) is a very important edible oil crop in the world, and the production is inhibited by abiotic stresses, such as salinity. Plant hormones can alleviate the stress by regulating the physiological processes and gene expression. To study the plant responses to salinity in combination with GR24, a synthesized strigolactone, the oilseed rape variety (Zhongshuang 11) replications were grown in the pots in a controlled growth chamber under three levels of salinity (0, 100, and 200 mM NaCl) and 0.18 μM GR24 treatments at the seedling stage for 7 days. The results showed that salinity depressed the shoots and roots growth, whereas GR24 improved the growth under salt stress. Leaf chlorophyll contents and gas exchange parameters (net photosynthetic rates, stomatal conductance, intercellular CO2 concentration, and transpiration rate) were also reduced significantly with increasing salinity, and these effects could be partially reversed by GR24 application. Additionally, GR24 treatment significantly increased and decreased the photosystem II quantum yield and non-photochemical quenching, respectively, under salinity stress conditions. The activities of peroxidase and superoxide dismutase increased, and lipid peroxidation measured by the level of malondialdehyde reduced due to GR24 application. The transcriptome analysis of root and shoot was conducted. Three hundred and forty-two common differentially expressed genes (DEGs) after GR24 treatment and 166 special DEGs after GR24 treatment under salinity stress were identified in root and shoot. The DEGs in root were significantly more than that in shoot. Quantitative PCR validated that the stress alleviation was mainly related to the gene expression of tryptophan metabolism, plant hormone signal transduction, and photosynthesis.
Highlights
Salinity is recognized as one of the major abiotic stresses that limits plant growth and productivity, in arid and semi-arid climates (Yamaguchi and Blumwald, 2005; Rozema and Flowers, 2008)
The results indicated that the root and shoot biomass increased significantly when Zhongshuang 11 (ZS 11) was treated by GR24 with the concentration of 0.18 μM, 1http://primer3.ut.ee/
In view of the results presented it is quite clear that salinity stress at the seedling stage resulted in a significant decline in root and shoot biomass accumulation
Summary
Salinity is recognized as one of the major abiotic stresses that limits plant growth and productivity, in arid and semi-arid climates (Yamaguchi and Blumwald, 2005; Rozema and Flowers, 2008). Salinity initiates complex responses to inhibit plant growth and physiological processes (Munns et al, 2006; Albacete et al, 2008; Naeem et al, 2012). Acosta-Motos et al (2015) mentioned that the negative impact of salinity stress on the photosynthetic apparatus, especially photosystem II (PSII), could be detected by imaging chlorophyll fluorescence, a non-invasive and quantitative tool (Buschmann et al, 2000; Oxborough, 2004). In addition to these stress effects, oxidative stress may occur
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