Functional Study Of SlatpA Gene In Resisitance Against Botrytis Cinerea And Pseudomonas Syringae In Tomato

Tomato（Solanum lycopersicum）is rich in nutrition and widely cultivated.It is not only one of the main economic horticultural crops,but also an important model plant in plant science research.The study of tomato is of great significance for agricultural production and scientific development.Tomato gray mold disease is caused by Botrytis cinerea,Tomato bacterial leaf spot is caused by Pseudomonas syringae pv.tomato DC3000（Pst DC3000）.They seriously harm the leaves,stems,flowers and fruits of tomato,resulting in reduced or even no yield.Therefore,mining disease resistance genes and their resistance mechanism has important theoretical and practical value.Tomato atp A gene（SlatpA）encodes chloroplast ATP synthase CF1αsubunit,which is an important component of photosynthesis and energy metabolism and participates in plant resistance to pathogens.Previous studies in our laboratory showed that tobacco overexpressing SlatpA showed increased resistance to Botrytis cinerea.Arabidopsis thaliana atp A gene responds to Pst DC3000 infection and plays an important role in the defense response induced by Pst DC3000.In order to study the function of SlatpA in disease resistance,transgenic tomatoes with overexpression of SlatpA were constructed and obtained,and the function of SlatpA gene in preventing tomato gray mold and bacterial leaf spot was explored from phenotypic,physiological and biochemical aspects.The main results are as follows:（1）The overexpression vector of SlatpA gene was cloned and constructed.Through gene cloning,the full-length 1524 bp of SlatpA gene was successfully constructed into p Super1300-GFP overexpression vector.（2）Transgenic tomatoes expressing SlatpA gene were screened and obtained.Using the genetic transformation method mediated by Agrobacterium tumefaciens,the overexpression vector of SlatpA gene was successfully transformed into AC tomato and 16 regenerated tomato plants were selected.11 positive plants were identified in DNA level,and the transformation rate was68.75%.The expression of SlatpA gene was detected by q RT-PCR.The results showed that the expression level of line 3 was the highest.（3）Overexpression of SlatpA gene increased the resistance of tomato to Botrytis cinerea.Under the infection of Botrytis cinerea,the expression of keratinase gene Bc Cut A,average lesion area,incidence and disease index of overexpressed（OE）plants were lower than wild type（WT）plants.The activities of disease defense enzymes（CHI,GLU,PAL,PPO）in OE increased significantly,the accumulations of H₂O₂,O₂^-and MDA in OE were less,and the expression of antioxidant enzyme genes（CAT1,APX2）in OE increased significantly in the later stage of infection.The decrease of photosynthetic parameters（Pn,Gs,Tr）and chlorophyll fluorescence parameters（Fv/Fm,ΦPSⅡ,q P）and the increase of intercellular CO₂ concentration（Ci）of OE were smaller,the non-photochemical quenching（NPQ）of OE increased significantly,and OE had more chlorophyll and ATP content.The SA content of OE increased significantly at 0-2 d after infection,the JA content of OE increased significantly at 3 and 5 d after infection,and the expression of disease resistance related genes（PR1,PR2,NPR1）of OE increased significantly.（4）Overexpression of SlatpA gene increased the resistance of tomato to Pseudomonas syringae.After Pst DC3000 infection,the number of disease spots,bacterial growth and dead cells in OE plants were less than WT.The CHI,GLU,PAL and PPO activity of OE increased significantly,the H₂O₂,O₂^-and MDA accumulation of OE decreased,and the CAT1,APX2expression of OE increased significantly.The decrease of Pn,Gs,Tr,Fv/Fm,ΦPSⅡ,q P and the increase of Ci of OE were smaller,the NPQ of OE increased significantly,and the contents of chlorophyll and ATP of OE were more.From 12 to 24 hours after infection,the SA content of OE increased significantly,while the JA content of OE decreased significantly,and the expression of PR1,PR2 and NPR1 of OE increased significantly.In summary,SlatpA gene enhanced resistance to Botrytis cinerea and Pseudomonas syringae by increasing the activity of disease defense enzymes and the expression level of resistance genes in tomato,participating in the regulation of SA and JA hormones,preventing excessive accumulation of ROS,maintaining the stability of photosynthesis.It provides a theoretical basis for further elucidating the mechanism of SlatpA gene in disease defense.