| The potted Paeonia suffruticosa Andr.‘Luoyanghong’ and ‘Wulongpengsheng’ were used as material, the dynamic changes of cell defense enzymes activity, osmotic adjustment substances content and malondialdehyde (MDA) content in the peony leaves in the process of drought stress and re-watering were studied; the dynamic changes of net photosynthetic rate (Pn), stomatal conductance (Cond), intercellular CO2concentration (Ci), transpiration rate (Tr) and water use efficiency (WUE) were also measured and analysed. When tree peony leaves of treatment group appeared phenomenon of permanent wilting and tree peony leaves of treatment group returned to a certain extent after re-watering, selected appropriate leaves of control group and treatment group respectively for transcriptome sequencing and analysis. In order to determine appropriate total RNA extraction stage of tree peony leaf, the Paeonia suffruticosa Andr.‘Luoyanghong’ was used as the test material. CTAB-LiCl improved method was chosen to extract total RNA from tree peony leaves at small bells stage, big bells stage, circular peach stage, flat peach stage, flaw stage, initial bloom stage and fading stage. RNA integrity was detected by agarose gel electrophoresis, RNA purity was detected by ultraviolet spectrophotometer. The main results are as follows:Firstly, activity of superoxide dismutase and catalase of two kinds of tree peony firstly increased, and then decreased. The activity of peroxidase of two kinds of tree peony increased gradually. After re-watering, compared with controls, superoxide dismutase activity of ‘Wulongpengsheng’ increased significantly, peroxidase activity of two kinds of tree peony changed indistinctively, catalase activity of ‘Wulongpengsheng’ increased significantly. Pearson correlation coefficient analysis showed that there was a significant or highly significant positive correlation between superoxide dismutase and peroxidase, catalase of ‘Luoyanghong’. Meanwhile, there was a significant positive correlation between superoxide dismutase and peroxidase of ‘Wulongpengsheng’.Secondly, with the soil water stress increasing, the content of soluble protein of the two kinds of tree peony increased firstly, and then decreased. The content of soluble sugar, proline and malondialdehyde showed an increasing trend. Compared with the severe drought, osmotic adjustment substances content of two kinds of tree peony all dropped, the differences of the other indexes were all significant except soluble protein of ‘Wulongpengsheng’. However, compared with controls, content of osmotic adjustment substances rised, but all the differences were indistinctive. Malondialdehyde content of two kinds of tree peony decreased to a certain degree, and the differences were both significant. However, the differences were indistinctive compared with controls.Thirdly, the net photosynthetic rate, stomatal conductance, intercellular CO2concentration, transpiration rate and water use efficiency of two kinds of tree peony all showed a trend of gradual decrease with the enhancement of drought stress intensity. After re-watering, the indexes all increased to a certain degree compared to control, some indexes even returned to the control level. The comparison of two varieties indicated that in process of the different water treatment, the net photosynthetic rate and water use efficiency of ‘Luoyanghong’ were both higher than ‘Wulongpengsheng’, which illustrated that the drought resistance of ‘Luoyanghong’ maybe stronger.Fourthly, after electrophoresis, the RNA extracted in seven stages all had three bands-28S,18S and5S rRNA, the ratio of A260nm/A280nm ranged between1.8and2.0. The rRNA bands at big bells stage, circular peach stage, flat peach stage, flaw stage, and initial bloom stage were tidy and clear, and the lightness of28S rRNA band was higher than18S rRNA band. The above showed that CTAB-LiCl improved method was suitable for extraction of total RNA from tree peony leaves, and big bells stage, circular peach stage, flat peach stage, flaw stage and initial bloom stage were the optimal five stages for total RNA extraction.Fifthly, the transcriptome sequencing were carry on six groups of tree peony leaves, the total number of each sample of the Clean reads all reached above51M, the number of All-Unigene was81725. The length of all Unigene was not less than200bp, the percentage of length between201bp and300bp was highest, was30.00%.43977Unigene obtained functional annotation when compared with six databases, they were NR database, NT database, Swiss-Prot database, KEGG database, COG database and GO database, the percentage was53.81%. Among them,51.24%of Unigene (the number of Unigene was41876) obtained homologous comparison information when compared with NR protein database. When compared two samples from six samples, the number of differentially expressed genes changed from5500to22000, there was the lowest number when compared WLPS-WT with WLPS-RE, there was the highest number when compared LYH-WT with WLPS-DR. |
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