| Low temperature is an important ecological factor affecting the planting and distribution of tea trees.Anti-cold damage is an important measure to improve the yield and quality of tea trees.At present,it has become a new way to apply exogenous cold-resistant substances to prevent low-temperature injury.In this experiment,potted seedlings and field tea trees were used to test the effects of GABA,Chlorella Powder and Bamboo Vinegar on sucrose related gene expression?SPS,SUS,INV4,INV5?and cold-tolerant related physiological indexes by spraying different concentration of the three kinds of exogenous substances under cold stress.Through the analysis of the expression levels of SPS,SUS4 and INV4 and INV5 of the key sucrose coding genes as well as the physiological indexes related to cold tolerance,the possible physiological and molecular mechanisms of the effect of exogenous substance spraying on the cold tolerance of tea trees were analyzed,In order to provide provided theoretical basis for the screening of cold resistance agents for tea trees.The main research results are as follows:1.In this experiment,tea plant seedling leaves were sprayed with different concentrations of GABA,Chlorella Powder and Bamboo vinegar,and their frost index and relative conductivity were measured after low temperature treatment.It was found that GABA,Chlorella Powder and Bamboo vinegar could significantly reduce the frost index and relative conductivity of tea plant leaves.Further measurement of malondialdehyde content and antioxidant enzyme activity in the leaves showed that the malondialdehyde content was significantly reduced and antioxidant enzyme activity was significantly increased in the leaves of tea plants treated with 10mmol·L-1GABA,0.22mg·mL-1 Chlorella Powder or2.5mg·mL-1 Bamboo vinegar.The results showed that GABA,Chlorella Powder and Bamboo vinegar could alleviate the membrane damage of tea tree under low temperature stress.2.In this experiment,the leaves of tea plant seedling and field Pingyang Tezao,Fuding Dabai were treated with 10mmol·L-1GABA,0.22mg·mL-1 Chlorella Powder or 2.5mg·mL-1Bamboo vinegar under low temperature stress,the chlorophyll content,root activity of tea plant seedling and the net photosynthetic rate of field tea trees were measured.It was found that the chlorophyll a content of tea plant seedling treated with GABA,Chlorella Powder and Bamboo vinegar increased by 7.18%,20.65%and 12.05%,and chlorophyll b increased by13.81%,28.25%and 14.84%,the carotenoids increased by 7.74%,14.91%,and 6.21%,the root activity increased by 56.54%,42.93%,and 39.79%,with significant differences.The net photosynthetic rate of tea trees in the field was significantly increased.3.It was find that the soluble sugar,proline and sucrose contents in the leaves of tea plants were on the increase under low temperature stress.Compared with water treatment,the soluble sugar content of tea plant seedling treated with GABA,Chlorella Powder and Bamboo vinegar after 72 hours of treatment increased by 21.06%,18.34%and 17.66%,proline content increased by 20.18%,26.78%and 23.67%,sucrose content increased by 15.24%,11.39%and5.97%.Soluble sugars and prolines,as small molecule osmotic regulators,are of significant important to improve the frost resistance of tea plant.4.The analysis of key genes of sucrose metabolism in tea plant seedling leaves under low temperature stress showed that the expression of SPS,SUS4,INV4 and INV5 increased significantly under low temperature stress,and the relative expression was further when treatment with GABA,Chlorella Powder and Bamboo vinegar.The relative expression of each gene reached the highest level,at the low temperature treatment for 24-48h.At 48h,the expression of SPS treated with GABA,Chlorella Powder and Bamboo vinegar were increased by 2.20 times,2.26 times and 2.06 times;the expression levels of SUS4 were increased by5.12 times,5.23 times and 5.43 times;the expression levels of INV4 were increased by 3.24times,2.86 times and 2.50 times;the expression levels of INV5 were increased by 4.52 times,5.22 times and 3.66 times;the difference was significant.The results showed the activity of various sucrose related enzymes and the level of expression of the coding gene such as SPS,SUS and INV,were induced treated with GABA,Chlorella Powder and Bamboo vinegar,and respond to low temperature by regulating sucrose metabolism. |
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