Study On Cross Adaptation Of NaCl Pretreatment To Improve Tomato Low Temperature Resistance

Low temperature leads to poor growth and development of tomato?Solanum lycopersicum?,affecting its yield and quality and causing economic loss.In recent years,people have improved the low-temperature resistance of crops by upgrading gardening facilities,spraying foreign substances,performing low-temperature exercise and cross-adaptation,in order to achieve the effect of stabilizing production.The cold tolerance of many plants is cross-adapted,such as tomato,rice,corn,banana,potato and spinach.A large number of studies have shown that the production of plant cross-adaptation is closely related to plant hormones,osmotic adjustment,active oxygen scavenging system,and heat shock protein.However,the mechanism of tomato salt-low temperature cross-adaptation is not yet clear.In this paper,Na Cl pretreatment of tomato seedlings and low temperature stress was conducted to explore the cross-adaptation approach of Na Cl pretreatment to improve tomato low temperature resistance.The main findings are as follows:1.Na Cl pretreatment significantly improves the photosynthetic capacity of tomato plants at low temperature and alleviates photoinhibition.Compared with the LT group,Na Cl pretreatment significantly alleviated the decrease of Pn,Tr,Ci and Gs of tomato plants at low temperature;the change trend of Fv/Fm and NPQ of Na Cl pretreatment group at low temperature was the same as that of tomato leaf gas exchange parameters.2.Na Cl pretreatment relieves the reduction of pigment content at low temperature.Na Cl pretreatment significantly increased the content of chlorophyll a,b and carotenoids at low temperature.At the same time,the relative expression of chlorophyll synthesis genes CAO1,DVR,HEMA1,and HEMD increased,and the relative expression of chlorophyll decomposition genes EEL,HCAR,NYC1,PIF4,PAO and others The amount of expression decreases.3.Na Cl pretreatment can change the morphology of photosynthetic organs in tomato leaves.Na Cl pretreatment alleviates stomata closure under low temperature stress: under normal temperature,Na Cl treatment tends to close the stomata of tomato leaves,but after low temperature treatment,the stomata opening of tomato in Na Cl pretreatment group is larger than that in LT group;and Na Cl pretreatment can increase ion channel related genes Relative expression of KAT1-1,SLAC1,QUAC1-1,QUAC1-2,KAT1-2 and tubulin genes BEAT-TUBULIN,MAP56-1a,TUB1-1;in addition,low temperature causes chloroplast starch granules to swell Increased number,disordered lamella granules,damaged chloroplast membrane,and Na Cl pretreatment can alleviate the above conditions,indicating that Na Cl pretreatment protects the chloroplast morphology of tomato leaves at low temperatures.4.Na Cl pretreatment enhances the ROS removal ability of tomato leaves at low temperature.The DAB and NBT staining of tomato leaves pretreated with Na Cl at low temperature was lighter than that of LT group,and the H₂O₂ content and O₂.-production rate were also significantly lower than those of LT group.Na Cl pretreatment significantlyenhanced the activity of tomato antioxidant enzymes SOD and POD at low temperature,and related gene expression levels.5.Na Cl pretreatment improves low temperature resistance through ABA metabolism and signal transduction pathways.Na Cl pretreatment increased the relative expression of ABA synthesis-related genes?AAO,ZEP1,NCED1?,ABA decomposition-related genes?CYP707A1,CYP707A1?and ABA signal transduction-related genes ABRE and MYB1 at low temperature;increased CBF1,CBF2,CBF3 and The relative expression levels of upstream related genes Solyc02g090390.3,Solyc01g108280.3,ICE1,ICEa,so as to enhance the low temperature resistance of tomato.