Abstract
BackgroundSalinity severely inhibit crop growth, yield, and quality worldwide. Allotetraploid rapeseed (Brassica napus L.), a major glycophyte oil crop, is susceptible to salinity. Understanding the physiological and molecular strategies of rapeseed salinity resistance is a promising and cost-effective strategy for developing highly resistant cultivars.ResultsFirst, early leaf senescence was identified and root system growth was inhibited in rapeseed plants under severe salinity conditions. Electron microscopic analysis revealed that 200 mM NaCl induced fewer leaf trichomes and stoma, cell plasmolysis, and chloroplast degradation. Primary and secondary metabolite assays showed that salinity led to an obviously increased anthocyanin, osmoregulatory substances, abscisic acid, jasmonic acid, pectin, cellulose, reactive oxygen species, and antioxidant activity, and resulted in markedly decreased photosynthetic pigments, indoleacetic acid, cytokinin, gibberellin, and lignin. ICP-MS assisted ionomics showed that salinity significantly constrained the absorption of essential elements, including the nitrogen, phosphorus, potassium, calcium, magnesium, iron, mangnese, copper, zinc, and boron nutrients, and induced the increase in the sodium/potassium ratio. Genome-wide transcriptomics revealed that the differentially expressed genes were involved mainly in photosynthesis, stimulus response, hormone signal biosynthesis/transduction, and nutrient transport under salinity.ConclusionsThe high-resolution salt-responsive gene expression profiling helped the efficient characterization of central members regulating plant salinity resistance. These findings might enhance integrated comprehensive understanding of the morpho-physiologic and molecular responses to salinity and provide elite genetic resources for the genetic modification of salinity-resistant crop species.
Highlights
Salinity severely inhibit crop growth, yield, and quality worldwide
Morphologic responses of oilseed rape to salinity Rapeseed plants were grown in hydroponic solution under 0, 50 mM, 100 mM, 150 mM, 200 mM, and 250 mM NaCl conditions to select the most suitable NaCl concentrations for the rapeseed salinity resistance study
Compared with the control condition, the rapeseed plants started to show obvious growth retardation, including leaf necrosis and root inhibition, when the NaCl concentrations were higher than 100 mM (Fig. 1a, b)
Summary
Salinity severely inhibit crop growth, yield, and quality worldwide. Allotetraploid rapeseed (Brassica napus L.), a major glycophyte oil crop, is susceptible to salinity. Soil salinity inhibits crop growth and development, which in turn reduces yield production, through a two-phase physiological dysfunction: (i) osmotic stresses that declines water potential and (ii) ion toxicity that disturbs ion homeostasis [6]. These stresses are associated with the disorder of a variety of biological processes, including cellular homeostasis imbalance, oxidative stress, essential nutrient dysfunction, protein synthesis disruption, retarded organ growth, and even plant death [7]. Some nonselective cation channels (NSCCs), K+ permeases, and other type transporters allow Na+ influx into plant cells [11]. Enhancing the biosynthesis of compatible osmolytes, antioxidants, and polyamines, and maintaining homeostasis of reactive oxygen species (ROS) and phytohormones are pivotal strategies for plants resistant to salinity stress [14]
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