Effects Of Drought,salt And Their Dual Stress On Capsaicin And Related Substances

Dried pepper is an important economic crop in Xinjiang.With the continuous expansion of its planting area,Xinjiang has become an important domestic production base for dried pepper raw materials.Dried chili has a wide range of uses,not only edible,but the capsaicin and capsaicin extracted from it can also be used in the fields of medicine,chemical industry,cosmetics and textiles,with high added value.Xinjiang has a large area of saline-alkali land due to soil parent material and climatic reasons.In actual production,the cultivation of dried peppers often faces dual stresses of salt-alkali and drought.In this study,the key environmental factors restricting the production of dried peppers in Xinjiang are drought and salt as the starting point,and three water gradients are set: W0(soil saturated water content is 100%),W1(soil saturated water content is 65%),W2(soil Saturated water content is 45%);2 salt concentrations: S1(Na Cl=50 mmol/L),S2(Na Cl=120 mmol/L),analysis of capsaicin-related metabolic enzymes and regulation under drought,salt and drought-salt stress Changes in genes,competing substances,and synthetic precursor substances,combined with plant growth and changes in capsaicin content,clarify the difference in response of capsaicin to salt and drought stress,and clarify the influence of environmental factors on capsaicin metabolism and its mechanism.Provide guidance for increasing capsaicin content in cultivation management.The experimental results are as follows:1.The higher the degree of drought,the higher the degree of inhibition of plant height and stem thickness of pepper,but the effect on the fruit shape index is not significant;the accumulation of dry matter under severe drought will be promoted in the green ripening period,and the red ripening period will be affected.Inhibition;under different concentrations of salt,the plant height,stem thickness,and single fruit weight will have low promotion and high suppression;the growth of pepper under dual stress is weaker than that of single stress,and its inhibitory effect on pepper is more significant.2.Under salt and drought stress,the capsaicin in the placenta changes more than the pulp;except for the W1 treatment in the red ripe period,drought,salt and their dual stress caused a significant decrease in the capsaicin content of the fruits at three different developmental stages;color conversion period The capsaicin content of W2 related treatment fruits showed a tendency of double stress lower than single stress.PAL enzyme activity increases with fruit development,and with the extension of the drought stress time,the promotion of PAL enzyme activity becomes more and more significant;drought,salt and drought salt stress will increase the activity of POD,and drought in the early stage of fruit development The higher the degree or the salt concentration,the stronger the POD activity,and the increase in POD activity will cause the reduction of capsaicin.3.The content of total phenols and capsaicin in the color conversion period and the red ripe period showed inconsistent changes.As a whole,with the extension of each stress time,the content of total phenols gradually increased;competing substances such as tannins and flavonoids gradually increased with the development of the fruit However,the overall lignin showed a downward trend.The combined stress of W2S2 significantly promoted tannins and flavonoids;under dual stress,the competitive effect of flavonoids and tannins with capsaicin was obvious.4.The expression of PAL gene continues to increase with fruit development.In the later stage of fruit development,except for W1S1 treatment,PAL gene expression can be promoted.The expression of AT3 in the color transition period was significantly increased,and the S2-related treatment had a significant effect on the promotion of AT3.The C4 H gene was stably expressed in fruits at different stages,but was greatly affected by salt and drought stress: W1S1 stress increased the C4 H expression the most during the three periods,and S1 stress decreased more.The expression of HCT gene during the red maturity period increased significantly.At this time,both salt and drought and its dual stress can promote the expression of HCT.5.Transcription analysis shows that the number of differential genes follows the rule of water stress<single salt stress <double stress;salt and drought stress mainly affects the phenylpropane metabolic pathway,followed by the phenylalanine pathway;salt stress affects the metabolism of each pathway Significant;the analysis of the expression of 43 genes related to capsaicin metabolism showed that the expression of 17 genes such as BCAT,KASIIIb,CCo AOMT were consistent with the capsaicin content,that is,the expression decreased under drought stress.CPR,p AMT2,PAT and other five genes all respond to three kinds of stress,while BCKDH E2,ENRb,ADT and other six genes are expressed under water stress,and CCR,GS2 and other 10 genes are mainly expressed under salt stress.