Effect Of SlSTN7 On D1 Protein Turnover In Tomato Leaves Under Low Night Temperature

Tomato is an important part of protected vegetable cultivation and production in China.However,protected tomato cultivation and production in winter and spring are often affected by night low temperature,especially in Northeast China.Low temperature at night will seriously damage the growth and development of tomato plants and significantly affect the photosynthetic capacity.In order to adapt to the changing environmental conditions,plants have evolved a series of mechanisms to regulate their physiological and biochemical processes,so as to ensure that they can still ensure high physiological activity in harsh environment.Among them,state transition is an important way for plants to regulate light energy distribution and ensure photochemical activity.Previous studies have shown that STN7 protein kinase can phosphorylate the light harvesting antenna complex of the optical system,make it move between optical system I and optical system II,and regulate the light energy distribution between optical system I and optical system II.However,whether STN7 affects the activity of the optical system through other ways has not been reported.Therefore,it is of great significance to study the mechanism of Sl STN7 on tomato crop photosynthesis at low temperature at night and clarify the effect of Sl STN7 on Tomato photosystem activity,especially the effect of Sl STN7 on D1 protein turnover.The main results of this test are:1.Clear overexpression of Sl STN7 can improve the photosynthetic capacity of tomato leaves under low night temperature.Overexpression of Sl STN7 significantly increased the photosynthetic capacity of tomato leaves at low night temperature,accompanied by the increase of stomatal conductance,transpiration rate and intercellular carbon dioxide concentration.It shows that overexpression of Sl STN7 alleviates the decline of photosynthetic capacity caused by non stomatal factors at low night temperature.2.Clear overexpression of Sl STN7 maintained the photochemical activity of PS Ⅱ in tomato leaves at low night temperature.Under low night temperature treatment,compared with AC wild-type tomato leaves,overexpression of Sl STN7 significantly maintained high levels of Fv / Fm,Y(Ⅱ),Y(NPQ),ETR(Ⅱ),and significantly reduced Y(NO).It is possible to maintain the activity of STN7 by the way of light dissipation.3.It was clear that overexpression of Sl STN7 maintained the photochemical activity of PS Ⅰin tomato leaves at low night temperature.Under low night temperature treatment,compared with AC wild-type tomato leaves,overexpression of Sl STN7 significantly maintained higher levels of p700 m,Y(Ⅰ),ETR(Ⅰ),and significantly reduced Y(ND)and Y(NA).The Y(ND)of tomato plant increased significantly under low night temperature,indicating that the decrease of photosystem I activity caused by low night temperature is mainly caused by the limitation of donor measurement.4.The effect of Sl STN7 on D1 protein turnover was confirmed.STN7 regulates the expression of D1 protein synthesis gene Psb A and degradation gene Deg1 at low night temperature.Through the interaction with Deg1 protein,STN7 regulates the DEG1-mediated D1 protein degradation pathway and the assembly of D1D2 protein complex at low night temperature,promotes the turnover of D1 protein,and plays a photoprotective role in tomato plants at low night temperature.