Effect Of Phosphorylation Site Ser-1040 Of Brassinolide Receptor SlBRI1 On Heat Tolerance Of Tomato

Tomato is a kind of widely planted warm vegetable,but it is not resistant to high temperature.In a large number of tomato planting areas in the north and south of China,the high temperature in summer is not conducive to the growth of tomatoes,so that the supply of tomatoes in August to October in autumn is off-season.To study the response mechanism of tomato to high temperature and cultivate varieties with high temperature tolerance can effectively alleviate the damage of high temperature and prolong the growth period of Tomato in summer.Brassinolide signal has an important influence on many aspects of tomato growth and development.The phosphorylation site of brassinolide receptor SlBRI1has been identified,but the function of phosphorylation site and its effect on tomato growth are not clear.In this study,Serine 1040?Ser-1040?,an important phosphorylation site in the activation region of SlBRI1 kinase in tomato,was studied.The plant expression vectors of S1040D and S1040A were constructed,and the weak mutant cu3^-abs1 of SlBRI1 was genetically transformed.The expression of S1040A and S1040D and the change of BR signal pathway of SlBRI1 were detected by using the transgenic material transformed into wild type SlBRI1 as the control.The seed germination,seedling growth,field growth and physiological characteristics of different mutants under high temperature stress were studied.The main results are as follows:1. In this study,SlBRI1 protein expression of S1040A and S1040D mutants was detected and confirmed.The results showed that the protein expression of S1040D was less than that of S1040A.2. BR signal transduction was detected in S1040A and S1040D mutants of SlBRI1.The results showed that there was no significant difference between S1040A and S1040D mutants and wild-type SlBRI1.3. The effect of Ser-1040 locus on the agronomic characters of tomato under high temperature stress was studied in the field.In the field experiment,high temperature stress had a great effect on the flower organs of tomato,among which the corolla and pistil were significantly elongated,the transgenic line of S1040D mutant was the most promoted,and the transgenic line of S1040A mutant was the least;and high temperature stress inhibited the growth of sepals,ovary,the number of flowers per year and the yield per plant,and the transgenic line of S1040D mutant was the most inhibited The transgenic line of S1040A mutant was the smallest.4. It was found that S1040 transgenic line was resistant to high temperature,so the effect of Ser-1040 on tomato seed germination under high temperature stress was studied.The results showed that high temperature stress inhibited the germination of tomato seeds,and the more obvious the inhibition was with the increase of temperature.37?had completely inhibited the germination of all lines of tomato seeds.Among them,S1040D mutant transgenic line was more inhibited than the control wild type,while S1040A mutant transgenic line was the opposite,with the lowest inhibition on seed germination.High temperature inhibited the growth of the underground part of tomato seedlings,but S1040A mutant transgenic line seedlings can alleviate the damage through the increase of proline,so as to improve their own resistance.The effect of Ser-1040 locus on the agronomic characters of Tomato under high temperature stress was studied in the field.In the field experiment,high temperature stress had a great effect on the flower organs of tomato,among which the corolla and pistil were significantly elongated,the transgenic line of S1040D mutant was the most promoted,and the transgenic line of S1040A mutant was the least;and high temperature stress inhibited the growth of sepals,ovary,the number of flowers per year and the yield per plant,and the transgenic line of S1040D mutant was the most inhibited The transgenic line of S1040A mutant was the smallest.5. The effect of Ser-1040 on the redox system was studied by biochemical experiments.Under high temperature stress,MDA content in leaves increased,SOD,POD,CAT and other antioxidant enzyme activities increased first and then decreased.The change range of different lines is different.The antioxidant enzyme activity of S1040A mutant is significantly higher than that of S1040D mutant under high temperature stress,and it can recover quickly after the stress is relieved,which shows that S1040A mutant can improve the antioxidant enzyme activity,effectively remove the active oxygen under high temperature stress,and alleviate the membrane quality caused by high temperature stress to a certain extent Oxidative damage.6. The effect of Ser-1040 on photosynthesis under high temperature stress.Under high temperature stress,the content of chlorophyll and net photosynthetic rate of tomato decreased significantly,and S1040A transgenic strain had the smallest change range and the strongest recovery ability,which indicated that eliminating phosphorylation of S-1040 could alleviate the damage caused by high temperature stress by inhibiting the degradation of chlorophyll and maintaining a high net photosynthetic rate.