Study On The Light Energy Conversion Performance Of High-quality Japonica Rice Nanjing 505

The good taste quality japonica Nangeng 5055 is cultivated by Jiangsu Academy of Agricultural Sciences.It has the characteristics of high quality,high yield and strong resistance.Through physiological and biochemical methods and protein analysis technologies,we studied the differences of light energy conversion performance between Nangeng 5055 and its parents and the variations of thylakoid membrane photosynthetic proteins during Nangeng 5055’s aging phases,which can provided reliable bases for further tapping its photosynthetic potential,selecting high-quality Parent Resources and improving offspring’s traits.The conclusions of this paper are as follows:（1）Compared with its parents,Nangeng 5055 has a longer growth times.The net photosynthesis rate,transpration rate,stomatal conductance,water use efficiency,chlorophyll（chlorophyll a,chlorophyll b）and carotenoid content,quantum yield(φ_Po,φ_Eo,φ_Ro),heat dissipation capacity（DI₀/RC）and photosynthetic performance index(PI_tot,PI_abs)of Nangeng 5055 were higher than Guandong 194 and slightly lower than Wugeng 13 in the reproductive period.Moreover,the seed-set rate and 1000-grain weight of Nangeng 5055 were higher than Guandong 194 and slightly lower than Wugeng 13 in the full-riping stage.The above results showed that the photosynthetic performance of Nangeng 5055 was close to its female parent of Wugeng 13.Nangeng5055 maintained the stable content of photosynthetic pigment and had high heat dissipation performance to avoid light inhibition in the later growth stage.It is speculated to be Nangeng 5055’s material and metabolic bases for it to maintain an efficient photosynthetic.（2）Blue-native polyacrylamide gel-electrophoresis（BN-PAGE）analysis showed that Nangeng 5055 had higher PSI complexes content than Wugeng 13,and the western blot indicated that Nangeng 5055 had higher Psa B,Lhca1 and Lhca2 protein content than Wugeng 13 in the booting and milk stages,while other complexes such as PSII core,LHCII complexes and theirs sub-units were slightly lower than that of Wugeng 13 but higher than that of Guandong 194.Those suggested that Nangeng5055 maintained the stable content of PSII core and LHCII proteins,and the content of PSI was higher than that of Wugeng 13 in the booting and milk stages.There were differences in the stability between the thylakoid membrane protein complexes of Nangeng 5055 during senescences.The PSI core and LHCI proteins in photosystem I were combined more closer than that LHCII and PSII core proteins in photosystem II.The content of photosynthetic protein complexes in Nangeng 5055 was different:LHCII>PSI>ATPase&Cytb₆/f>PSII core>PSI core,and their degradation rates were asynchronous:LHCII>PSI>ATPase&Cytb₆/f>PSII core>PSI core.The above results indicated that Nangeng 5055 contained high and stable PSI and LHCII protein contents during its aging stages.（3）In the aging processes,the maximum photochemical efficiency（F_v/F_m）,heat dissipation capacity（DI₀/RC）,PSII photosynthetic performance index(PI_abs),comprehensive photosynthetic performance index(PI_tot)and photosynthetic pigment content of Nangeng 5055 were reduced.In addition,Ca²⁺-ATPase and Mg²⁺-ATPase activities of Nangeng 5055 were decreased.The results of Blue-native PAGE with mass spectrometrytandem identification showed that the proteins degraded in the chloroplast of Nangeng 5055 were mainly photosynthetic-related proteins during its senescence stages.These proteins mainly included photosystem I core protein,photosystem II core protein,chlorophyll binding protein and ATP synthase protein.The above results indicated that in the senescence stages,the decrease of photosynthetic pigment content and photosynthetic protein content and heat dissipation capacity（DI₀/RC）of Nangeng 5055 affected its absorption,transformation and transmission of light energy,and resulted in the maximum photochemical efficiency（F_v/F_m）,PSII photosynthetic performance index(PI_abs),comprehensive photosynthetic performance index(PI_tot),Ca²⁺ATPase and Mg²⁺-ATPase activities decreasing,thereby limiting the ability to increase its production.