| The arid and semi-arid area of China accounts for more than half of the total land area.Drought stress has become a key factor restricting the growth and development of crops,which seriously affects the physiological characteristics of crops and leads to a decline in both yield and quality.Cabbage is a kind of vegetable which needs a lot of water.It is of great significance to study the drought resistance of cabbage in order to improve its drought resistance and its yield and quality.In this study,the seed germination rate and seedling drought resistance of two cabbage cultivars were analyzed by different concentrations of PEG-6000（10%,20%,30%） to simulate drought stress,and different concentrations of salicylic acid(0.5,1.0,2.0 mmol·L-1) were sprayed to improve their adaptability under drought stress.At the same time,the aquaporins gene family of cabbage was identified by bioinformatics technology,and its related characteristics and gene expression were analyzed.The main results are as follows:（1）The germination rate and germination potential of cabbage seeds were slightly increased by 10%PEG-6000 simulated drought treatment,but there was no significant difference between them and the control 20% PEG-6000 simulated drought significantly reduced the germination potential and germination rate of seeds.（2）Drought-stress reduced the relative water content of the two cabbage varieties,and the 30%PEG-6000 simulated drought treatment was the most significant.At 3d,Qingan78 and Qingan 50 decreased to 64%and 48%,respectively,and both of them returned to similar levels of the control after rehydration.The activity of peroxidase（POD）gradually increased with the deepening of drought stress and the prolongation of drought stress time,and reached the highest when the 30% PEG-6000 simulated drought for 3 days,and then decreased rapidly after rehydration.The activity of superoxide dismutase（SOD）increased rapidly in the fourth day after drought stress treatment and reached the highest value during the whole treatment period,which was significantly higher than that of the control,and decreased in the following periods.The content of malondialdehyde（MDA） increased rapidly at the fourth day after treatment and reached the highest value,which was significantly higher than that of the control.There was a decrease in the later period,but it was all significantly higher than the control.The content of Qingan 78 decreased to the control level after rehydration,and there was no significant difference between Qingan 78 and the control.Qingan 50 also decreased,but 30% PEG-6000 simulated drought treatment was still significantly higher than the control.（3）The study on the effect of exogenous salicylic acid on drought resistance of cabbage showed that different concentrations of exogenous salicylic acid could increase the peroxidase（POD） activity of Qingan 78,and there was no significant difference between the three concentrations.However,the peroxidase（POD）activity of Qingan 50 decreased.In addition,the activity of superoxide dismutase（SOD）in cabbage leaves was increased.In Qingan 78,the three concentrations were significantly higher than the control group,while in Qinggan 50,only 2 mmol·L-1 was significantly higher than the control group.At the same time,the content of malondialdehyde（MDA）increased,and 0.5 mmo·L-1treatment increased the most significantly.（4）Through bioinformatics,36 aquaporins gene family members of cabbage were identified,which were divided into four subfamilies,among which 24 were basic proteins,34 were relatively stable proteins,and 36 were hydrophilic proteins.The genetic structure of the same subfamily members is very conservative.Contains more homeopathic elements related to environment and hormones;And has 30 pairs of collinearity genes with Arabidopsis thaliana.Drought-stress can down-regulate BoPIP2-7,BoTIP1-1,BoTIP1-2,BoNIP2-1,BoNIP5-1,and up-regulate BoPIP2-2 and BoTIP2-2,indicating that these genes are in response to drought stress.The expression of most genes was down-regulated after the application of salicylic acid. |
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