Physiological Characteristics And Gene Expression Of A Green-Revertible Albino Bamboo-Pseudosasa Japonica F. Akebonosuji H. Okamura

Pseudosasa japonica f.akebonosuji H.Okamura is a rare ornamental bamboo,stalk type tall and straight,leaf color changeable,has important ornamental value.In this paper,the relative leaf SPAD was measured by using no chlorophyll from the leaves of the green leaves of the green leaves,and the leaves of different green degrees were screened.The green degree?SPAD value?was 0,10%,30%,50%,70% and 90% of the control green leaves,which were divided into five stages.The leaf green model was studied.Chlorophyll content,chloroplast ultrastructure,photosynthetic characteristics and albino turn green-related gene expression differences were discussed.The results showed that?1?Compared with the green plant of Pseudosasa japonica f.akebonosuji,the mosaic leaves were smaller and the stalk was lower,but the growth rate and the pumping time were similar.In the mosaic plant,the first 1-3 leaves were white,4-7 leaves were light green and 3-7leaves can reach green..?2?Photosynthetic pigment content in white leaf of Pseudosasa japonica f.akebonosuji was very low.In the process of return-green,the content of photosynthetic pigment in the leaves was decreased,and the contents of chlorophyll a,chlorophyll b,total chlorophyll and carotenoid contents in 90%return-green leaves were 87.02%,98.20%,89.37% and 85.02% of green leaves.Chlorophyll b reached green leaf level,but chlorophyll a,total chlorophyll and carotene contents didn't,which belonged to chlorophyll a deficiency mutation.?3?The ultrastructural changes of chloroplast were significant,and a lot of plastids were found in the white leaves,but the green leaves of the green leaves were clear and uniform.The chloroplast membrane structure of the green leaf changed gradually as follows: the vesicle-like vesicles formed by the intima of the chloroplast were formed into a single layer,and then gradually formed into a base grain,and finally,And the formation of thylakoid membrane system with complete photosynthetic function.The process of complex green is accompanied by the gradual disappearance of osmium particles and the occurrence and increase of starch granules in the middle of complex green.The mumber of the leaf chloroplast 90% complex return-green of was only 51.38% of the control.?4?The net photosynthetic rate and the intercellular CO₂ concentration in the process of return-green leaves was significantly increased,the transpiration rate increased slowly,and the stomatal conductance changed little,indicating that the photosynthetic rate was affected by the non-stomatal factors.The light saturation point rised,and the light compensation point decreases,the dark respiration rate of green leaves was not significantly different between return-green leaves and green leaves.The apparent quantum efficiency of green leaves was only 78.66% of green leaves,indicating that although light energy utilization was improved,electron transfer efficiency of return-green leaves was still lower than green leaves.Vcmax and Jmax increased gradually in the process of return-green,but the change of Jmax / Vcmax was not obvious,indicating that the Rubisco content andthe regeneration rate of RuBP were gradually restored at a closing speed.Fv / Fm,Y?II?and ETR were significantly increased,indicating PSII reaction center was increased when the photosynthetic pigment content increased,Fo,NPQ and Y?NPQ?increased first and then decreased,indicating the light energy and photochemical conversion efficiency are gradually restored.The utilization rate of light energy is low and the heat dissipation capacity of the leaves is weak,which is easy to cause light damage at the early stage of return-green process.Pm and ETR?I?gradually increased in teturn-green leaves and Y?ND?decreased,indicating that the total amount of P700 and the percentage of P700 in the oxidation state gradually increased,and the electron transfer rate was accelerated.The reduction of the ratio of Y?I?/ Y?II?in the process of return-green leaves reflects the gradual recovery of ring electron transport capacity and the enhancement of PSII and PSI.Y?II?,ETR of return-green leaves were still significant different from those of the green leaves,we concluded that the photosynthetic electron transport chain using for carbon fixation existed different between green leaves and complex return-green leaves.?5?The relative expression levels of PjAL1,PjTCD10,PjELIP2,PjASL2,PjClpP5,PjV5 B,PjV1and PjWLP1 in the complex return-green leaves and green leaves were more than 2 times.According to the function of homologous genes,we speculated that PjELIP2 is involved in thylakoid protein assembly,PjASL2,PjWLP1 involved in chloroplast ribosome processing,PjTCD10,PjAL1,PjV1,PjV5 B and PjCLpP5 have a role in regulating the chloroplast structure [140].We Suggested that these genes are involved in the synthesis and degradation of chloroplast proteins during leaf greening.In addition,the expression of PjFtsH1,PjYSA,PjWP1,PjV3 and PjV5 A genes was not significantly different between teturn-green leaves and green leaves,and it is likely that these genes do not have a direct effect on Mosaic maintenance.In summary,different leaves were gradually increased from the leaf base to the leaf tip,and the chlorophyll levels of the different green levels were gradually increased,but chlorophyll a was significantly lower than that of green leaves,so we indicated it a kind of chlorophyll a deficient mutants.In the process of return-greening,the chloroplast endometrial system was reconstructed,which was an important non-stomatal factor.The accumulation of chlorophyll is the direct cause of green-revertible Albino phenomenon.The chloroplast thylakoid membrane system reconstructs the photosynthetic system,making the photosynthetic capacity increasing.The different expression of genes related to chloroplast protein synthesis and degradation may lead to albino leaves can not be completely return to green.