Transcriptome Analysis On Response Of Photosynthetic Capacity Of Larix Gmelinii Needle To Climate Warming

Tree photosynthesis is the basis for energy flow and material cycling in terrestrial ecosystems.It is important for the physiological process of temperature response and adaptation.Larix gmelinii is an important plantation tree species in China and a dominant tree species in boreal forests.It grows in climate change-sensitive areas,making it an ideal tree species for studying the response mechanism of trees to climate change.In this study,larch saplings from were transplanted from four locations at different latitudes(Tahe,Songling,Heihe and Dailing from north to south)to a common garden(Maoershan)at the southern edge of the distribution area for the purpose of simulating climate warming.High-throughput sequencing technology was used to determine the transcriptome of larch leaves,to study the differences of leaf photosynthesis-related genes among four sites,and to analyze the effects of different degrees of warming on leaf photosynthesis-related genes.The main results are as follows:Transcriptome sequencing analysis of four original sites of larch leaves showed that in the photosynthesis pathway,the expression genes was up-regulated with the increase of the annual average temperature of the sites.Those included the genes encodeing photosystem II-related protein subunits(Psb B,Psb K,Psb O,Psb P,Psb Q,Psb S,Psb W,Psb27,and Psb28)and genes encoding the protein subunits of F-type ATPases(ATPF1A,atp A,ATPF1 G,atp G and ATPF1 D,atp H)were significantly upregulated,which was helpful enhancement of photosystem performance in the leaves of larch.In the nitrogen metabolism pathway,the genes encoding Glutamine synthetase,Nitrate reductase,Carbonic anhydrase,Glutamate dehydrogenase and Glutamate synthase was significantly up-regulated with the increase of the annual mean temperature of the sites,which helped to promote the nitrogen use efficiency of trees.In the photosynthesis-antenna protein pathway and the porphyrin and chlorophyll metabolism pathway,the genes encoding light-harvesting chlorophyll protein complexes(LHCA2,LHCB1,LHCB2,LHCB4,LHCB5,LHCB7)and encoding Chlorophyllase,Chlorophyll b reductase and Ferredoxin oxidoreductase showed a significant up-regulated trend,which contributes to the process of light absorption and chlorophyll metabolism and promotes photosynthesis.This indicates that after long-term adaptation to the local environment,the genes expression of photosynthetic capacity-related pathways such as light energy capture,carbon fixation,nitrogen synthesis,and chlorophyll synthesis in larch.And with the increase of temperature between sites,genes up-regulated expression was obvious,which led to intraspecific differences in leaf photosynthetic capacity.After transplanting and warming treatment,the part of genes expression related to leaf photosynthesis were changed,and the genes encoding photosystem II(Psb B、Psb D、Psb K、Psb O 、 Psb P 、 Psb Q 、 Psb S 、 Psb W 、 Psb27 、 Psb28)were significantly up-regulated.Differentially expressed genes related to nitrogen metabolism,photosynthesis-antenna protein,porphyrin and chlorophyll metabolism pathways encoded Glutamine synthetase,Nitrate reductase and Carbonic anhydrase,light-harvesting chlorophyll protein complex(LHCA2,LHCB1,LHCB2,LHCB4,LHCB5,LHCB7),Chlorophyllase,Chlorophyll b reductase and Ferredoxin oxidoreductase genes were all significantly up-regulated.We analyzed the differentially expressed genes between 4 sites before and after warming treatment that a total of 58 genes related to photosynthetic capacity were screened out.The expression trend of genes changed,and the genes from up-regulated to down-regulated were significantly more than from down-regulated to up-regulated.These genes include encoding photosystem I(Psa N,Psa D),photosystem II(Psb S),photosynthetic electron transport(Pet J,Pet F),Glutamine synthetase,Carbonic anhydrase,light-harvesting chlorophyll protein complexes(LHCA2,LHCB1,LHCB5)and Ferredoxin oxidoreductase.This indicates that part of differential expression genes related to photosynthesis between the four sites still exists after warming,while the expression of some genes is no longer different.Transcriptome analysis showed that climate warming changed the expression of photosynthetic capacity-related genes in larch leaves,and the up-regulation of some genes contributed to the improvement of photosynthetic capacity.The expression of leaf photosynthetic capacity-related genes was significantly different among the four sites,and the expression of some genes changed before and after climate warming.This indicated that the expression of photosynthetic capacity-related genes in larch leaves was controlled by its own genetic characteristics and the external environment.This study is of great significance for the in-depth study of the response mechanism of larch to climate change.