Changes in Photosynthetic Traits, Cloning and Characteristics Analysis of KpPetC Gene Involving in Photosynthetic Electron Transfer of Koelreuteria paniculata ‘Jinye’

LU Hailin, WU Ruqian, AN Xinmin*

(State Key Laboratory of Tree Genetics and Breeding, National Engineering Research Center of Tree Breeding and Ecological Restoration, Advanced Innovation Center for Tree Breeding by Molecular Design, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing 100083, China)

Abstract:

The cytochrome b6f complex is a potential limiting factor in plant photosynthetic electron transfer, and increasing the activity of this complex may improve the efficiency of photosynthesis. It is of great scientific significance to investigate key genes involved in photosynthetic electron transfer. In this study, starting from color variation phenotype in Koelreuteria paniculata ‘Jinye’, and using K. paniculata and its mutant K. paniculata ‘Jinye’ as experimental materials. The photosynthetic physiological indicators was measured by Li-COR6800 photosynthetic analyzer during the growth period. Then the PetC gene involved in the photosynthetic pathway was isolated by RT-qPCR, and comprehensive bioinformatics analysis was conducted by online tools. Furthermore, the expression patterns of PetC gene in different tissues and its dynamic expression in leaves of different development stages in K. paniculate were detected using RT-qPCR. Meanwhile, the correlation between KpPetC gene expression and net photosynthetic rate was analyzed. Additionally, an overexpression vector containing tandem KpPetC and eGFP with P2A elements was also constructedand and carried on ectopic genetic transformation in 84K poplar. The results showed that the net photosynthetic rate and transpiration rate of K. paniculata ‘Jinye’ were generally downregulated, while the intercellular CO2 concentration was significantly increased. These results indicated that the decreasing of photosynthetic rate in K. paniculata ‘Jinye’ was mainly caused by non-stomatal limitation. The strong light and high temperature in July might damage the photosynthetic elements of K. paniculata ‘Jinye’, resulting in serious inhibition of photosynthesis, and the tolerance to light of K. paniculata ‘Jinye’ was weakened. The results of RT-qPCR assay revealed that KpPetC presented constitutive expression patterns in different tissues, but high abundant transcripts detected in leaf, and its expression in K. paniculata leaves was significantly higher than that in K. paniculata ‘Jinye’ in different development stages. And there was a positive correlation between the net photosynthetic rate and the expression of KpPetC in K. paniculata and K. paniculata ‘Jinye’. These data suggested that the down-regulation of KpPetC gene expression might be one of the main reasons for the decline of photosynthetic rate in K. paniculata ‘Jinye’. In conclusion, compared with K. paniculata, the photosynthetic capacity of K. paniculata ‘Jinye’ was significantly down-regulated. This might be due to the inhibition of KpPetC gene expression, which impairs some elements in the photosynthetic pathway, and ultimately affects the photosynthetic electron transport rate. These results provide a basis for future studies of PetC gene function and has important scientific significance for the study of photosynthetic electron transport mechanism.

CSTR: 32200.14.cjcb.2024.05.0005