Abstract
Soil salinization is one of the main stress factors that affect both growth and development of plants. Hylotelephium erythrostictum exhibits strong resistance to salt, but the underlying genetic mechanisms remain unclear. In this study, hydroponically cultured seedlings of H. erythrostictum were exposed to 200 mM NaCl. RNA-Seq was used to determine root transcriptomes at 0, 5, and 10 days, and potential candidate genes with differential expression were analyzed. Transcriptome sequencing generated 89.413 Gb of raw data, which were assembled into 111,341 unigenes, 82,081 of which were annotated. Differentially expressed genes associated to Na+ and K+ transport, Ca2+ channel, calcium binding protein, and nitric oxide (NO) biosynthesis had high expression levels in response to salt stress. An increased fluorescence intensity of NO indicated that it played an important role in the regulation of the cytosolic K+/Na+ balance in response to salt stress. Exogenous NO donor and NO biosynthesis inhibitors significantly increased and decreased the Na+ efflux, respectively, thus causing the opposite effect for K+ efflux. Moreover, under salt stress, exogenous NO donors and NO biosynthesis inhibitors enhanced and reduced Ca2+ influx, respectively. Combined with Ca2+ reagent regulation of Na+ and K+ fluxes, this study identifies how NaCl-induced NO may function as a signaling messenger that modulates the K+/Na+ balance in the cytoplasm via the Ca2+ signaling pathway. This enhances the salt resistance in H. erythrostictum roots.
Highlights
Soil salinization is one of the main environmental stressors for plants, and one of the main factors that restrict agricultural and forestry production
The volcano plots of differentially expressed genes (DEGs) between samples are shown in Supplementary Fig. S4A, and the DEGs were identified between two samples by comparing T0 and T5, T5 and T10, and T0 and T10 (Supplementary Fig. S4B)
This study identified several unigenes that were annotated to Na+ and K+ transporters in H. erythrostictum roots, including salt overly sensitive 1 (SOS1), AKT1, NHX1, and NHX2, the expressions of which were enhanced in response to salt stress
Summary
Soil salinization is one of the main environmental stressors for plants, and one of the main factors that restrict agricultural and forestry production. Nitric oxide (NO) is an important gaseous signal molecule, which plays a key role in a number of physiological processes in plants These include root formation, seed germination, seedling growth, stomatal closure, maturation, flowering, senescence, programmed cell death, as well as biotic and abiotic stress responses[19,20,21]. After treatment with 200 mM NaCl for 0 (T0, control), 5 (T5), and 10 (T10) days, RNA-seq was performed to identify the potential candidate genes related to ion transportation and NO biosynthesis that have differential expressions in the roots of hydroponic H. erythrostictum seedlings. This study provides important information toward discovering the salt-resistance mechanisms in the roots of CAM plants This information is used to explore the pathways for enhancing the salt-resistance of other horticultural plants to utilize and improve high-salinity soil
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