Regulation of the photochemical reaction of photosystem Ⅱ by extracellular ATP under pathogen infection
In order to explore the changes in extracellular ATP(eATP)levels and regulation of photo-chemical reaction by eATP under pathogen infection,a wild type Col-0 and eATP receptor mutant dorn1-3 of Arabidopsis were used as experimental materials,and it was found that the infection with either virulent pathogen(Pst DC3000)or avirulent pathogen(PstavrB)resulted in a decrease of eATP levels,values of the maximum photochemical efficiency under light adaptation(Fv'/Fm'),actual photo-chemical efficiency of PSⅡ(Y(Ⅱ))and photosynthetic electronic transmission rate(ETR),but an increase in the quantum yield of non-regulated energy dissipation(Y(NO))of the leaves.By a com-parison between wild type Col-0 and eATP receptor mutant dorn1-3 of Arabidopsis seedlings,it was revealed that,under Pst DC3000 infection,the values of Fv'/Fm',Y(Ⅱ)and ETR of dorn1-3 plants were slightly lower than those of the wild type,while the Y(NO)was slightly higher than those of the wild type.Under PstavrB infection,the values of Fv'/Fm',Y(Ⅱ)and ETR of the dorn1-3 plants were signifi-cantly lower than those of wild type plants,while Y(NO)was significantly higher.The results above indicated that the mutation of eATP receptor could exacerbate the inhibition of the pathogen infection on the photochemical reaction of PSⅡunder pathogen infection,and such effect of the mutation of eATP receptor was more significant under PstavrB infection.It was suggested that eATP could play an impor-tant role in regulating the photochemical reaction of PSⅡ under pathogen infection.