| A hydroponic experiment was conducted to study hydrogen peroxide?H2O2?,super oxide(O2·-)contents in leaves,and the enzymes activities of N metabolism in root,stems and leaves of sour jujube seedlings by different concentrations of CaCl2(0,5,10 and 20 mmol·L-1)under NaCl stress(150mmol·L-1).This experiment also constructed four small molecule RNA libraries in 6h?150 mmol·L-11 NaCl?150 mmol·L-11 NaCl+10 mmol·L-11 CaCl2 treatment?.We compared the length distribution,statistics of count,classification,and annotation of different samples.And the differential expression of miRNA and target genes in the Na treatment,Na and plus Ca treatment were analyzed in order to provide the basis for revealing the regulation mechanism of CaCl2 on the alleviation of jujube seedlings under NaCl stress.Main research results are as follows:1.The results showed that 5 and 10 mmol·L-1 CaCl2 significantly reduced H2O2 and O2·-contents in the leaves of NaCl-stressed sour jujube seedlings.The 5 and 10 mmol·L-11 CaCl2treatment significantly increased GOGAT activity in roots and stems.All of the CaCl2treatments significantly increased GOGAT activity in leaves.Leaf GS and NR activity were significantly increased by all of the CaCl2 treatments.Root GS and NR activity were significantly increased by 10 and 20 mmol·L-1 CaCl2,whereas 5 mmol·L-11 CaCl2 had no significantly effect.Stem GS and NR activity were significantly increased only by 10mmol·L-11 CaCl2.All of the CaCl2 treatments significantly increased protein contents in roots,stems,and leaves.The 10 and 20 mmol·L-11 CaCl2 increased free amino acid contents in roots and stems,whereas only the 10 mmol·L-11 CaCl2 treatments significantly increased free amino acid contents in leaves.The 10 mmol·L-11 CaCl2 treatment significantly increased NO3-N concentrations in roots and stems.All three CaCl2 treatments increased NO3-N concentrations in leaves.The 150 mmol·L-1 NaCl stress treatment caused significantly peroxidative damage to wild jujube seedlings and inhibited N metabolism.Exogenous CaCl2 helped the sour jujube seedlings adapt to NaCl stress by promoting the assimilation of NH4+via the GS/GOGAT cycle in roots and stems and by increasing NR activity and regulating NO3-N transformation rates.The results showed that 10 mmol·L-1 CaCl2 was the most effective treatment for alleviating NaCl stress in sour jujube seedlings.The GOGAT activity,NR activity,and free amino acid concentrations can be used to evaluate the ability of CaCl2 to alleviate NaCl stress in sour jujube.2.Through the analysis of the small RNA sequencing data,we obtained 106,295,326 clean tags.75.54%and 75.83%were perfectly mapped to jujube genome in the Na and NaCa treatment of sour jujube leaves;64.68%and 69.09%were perfectly mapped to jujube genome in the Na and NaCa treatment of sour jujube leaves.The clean reads length of the four samples was mainly distributed in 21nt.There were 318 known differential miRNA,775differential target genes,204 predicted differential miRNA and 625 differential target genes in roots and leaves of jujube seedlings.Compared with Na treatment,the most differentially expressed genes were leaves,with 30 up-regulated and 30 down-regulated genes respectively.There were 64 up-regulated and 56 down-regulated genes in roots and leaves treated with Na.According to the GO functional classification and KEGG pathway annotation in the target genes of miRNA in jujube leaves and roots,there were 2006 target genes differentially expressing miRNAs,and 34 GO conditions were enriched.These target genes were involved in the process of cell and metabolism process.The most significantly KEGG pathway is“signal transduction”.3.miRNA and mRNA in leaves and roots of sour jujube seedlings were verified by qPCR.The results showed that the expression trend of miRNA in four comparison groups was consistent with the result of sequencing.There is a negative correlation between partial miRNA and target gene,the reliability of sequencing data was preliminarily confirmed. |
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