| Peach cultivation has a long history in the Sichuan Hilly Basin.The soil in this area is purple shale rock alkaline soil,which causes peach yellowing and thereby seriously affects the growth and development of peach.In order to identify the difference between resistant material GF677 and common wild peach in photosynthetic capacity in alkaline soil,we took biennial GF677 cutting seedling and wild peach seedling as materials,compared their progresses of chlorophyll biosynthesis precursors at different stages as well as composition variances,emploied Transmission Electron Microscopy(TEM)to examine the ultra-microstructure of chloroplast,and used the LI6400-XT portable photosynthesis measurement system to compare their photosynthesis and chlorophyll fluorescent parameters,to provide a theoretical basis for screening of high-photosynthetic-efficiency and anti-yellowing peach germplasm resources in the future.The results showed:(1)At multiple stages from May to October,the contents of chlorophyll a,chlorophyll b and the total chlorophyll amount contained in the leaves of GF677,as well as Urogen III,Proto IX,the Mg-Proto IX,and original chlorophyllide,were higher than all those of prunus persica.In the leaves of GF677,Proto IX,Mg-Proto IX and original chlorophyllide were interfered by alkaline stress,but it soon recovered from a previous transient drop in these contents and then outdone,whereas peach behaved low performance.Peach chlorophyll b content has been always significantly lower than GF677 at any stages,which could be used to explain leaf chlorosis;The synthesis procedure,including the conversion of PBG into Uro,and Uro into Proto,and the conversion of chlorophyll a into chlorophyll b,the process of chlorophyll circulation,all of those were determinant references to capability estimation of yellowing resistance of peach rootstocks.(2)Whether he plant chlorophyll synthesis of PBG → Uro,Uro → Proto two steps,and the chlorophyll loop transformation between chlorophyll a and chlorophyll b is blocked or not,are three important judgments of peach rootstocks’santi-yellowing indicators(3)GF677 cannot only produce the output of photosynthesis faster under low light and low CO2 concentration,but also use high CO2 concentration conditions to achieve higher net photosynthetic rate.And the photoreactive center of the GF677 is more open than wild peach,with higher electron transfer speed and light energy conversion efficiency.(4)GF677 leaves forming more active chemical energy(ATP and NADPH)than wild peach,able to provide more dark reaction of carbon assimilation energy,so as to promote the efficiency of carbon assimilation and accumulation of organic matter.(5)GF677 could reduce non-chemical energy dissipation and antenna heat dissipation in the PSII reaction center,and apply excess excitation energy to photochemical reaction to increase the yield of chlorophyll fluorescence and protect the photosynthesis organs,so its PSII system has higher thermal stability than wild peach. |
