Effects Of Cell Redox Signal On Anthocyanin Synthesis In Leaves Of Begonia Semperflorens

In recent years,plants with colorful leaves are becoming more and more popular due to their characteristics of unusual and rich leaves,which have become an indispensable element of the city landscape and greening.The most influential application of colored-leaf plants is the landscape of ‘autumn red leaves’,which have become a symbol of many cities,such as Beijing Xiangshan.The presentation of colorful leaves is related to a secondary metabolites of flavonoids,anthocyanins,which can give the different tissues of plant body in red,blue and purple colors,the main material of the colored-leaf plants as well,the leaves of many plants in biotic and abiotic stress can form the anthocyanin,so plants have obviously apparent characteristics.Therefore,this study selected the Begonia semperflorens of ‘Super Olympia’(green leaf)as materials,analysed in three aspects:mechanism of oxidation-reduction signal mediated anthocyanin stress-induced synthesis in cells;H2O2 distribution and source when different H2O2 inhibitor participate in low-temperature-induced procession of anthocyanin synthesis;transcriptome sequencing of Begonia leaves when their anthocyanin synthesis were induced by environment.Main research results as follows:(1)The final form of oxidation-reduction is the production of ROS,therefore,we speculate that ROS,especially H2O2,may serve as a signal medium in autumn-low-temperature leads the synthesis of anthocyanins in stress-induced.Begonia leaves at 0.05 and 0.1 mmol·L-1MV treatment had trendency that significantly changed to red in the first 9 day,and the content of anthocyanin and ROS increased significantly;while 2 and 5 mmol·L-1DMTU treatment of Begonia leaves did not have the trendency to change to red,and content of anthocyanin and ROS significantly decreased with the prolonging of time,then became stable.In order to verify further,we selected Begonia leaves treated in 5 mmol·L-1DMTU,found that DMTU can clearly eliminate the content of ROS under low temperature stress,anthocyanin synthesis genes PAL,CHS,F3 H and ANS expression down to decrease the content of anthocyanin.In the As A-GSH cycle by reducing the content of As A,GSH and other antioxidants,the activity of CAT,APX,and SOD,MDHAR,DHAR and GR,and other antioxidant enzymes,alleviate the decreasing of low temperature stress on chlorophyll fluorescence parameters.These results showed that MV promotes the increase of activeoxygen content,producing the oxidative stress while inducing the production of anthocyanin,and the clearance of H2O2 by DMTU after low temperature stress,anthocyanin synthesis induced by low temperature was also inhibited.Therefore,the test results indicated that H2O2 is associated with the anthocyanin synthesis induced by the environment.(2)Previous research indicated that H2O2 was involved in the anthocyanin synthesis with the environmental impact.In order to research the source of H2O2 production and accumulation in Begonia leaves under low temperature stress,we applied that different H2O2 inhibitors to Begonia leaves and results showed that the anthocyanin content,H2O2 content and distribution,MDA content,Evans blue uptake,SOD,POD,PAO,GO activity and anthocyanin synthesis genes expression such as PAL,CHS,F3 H,ANS in flower leaves was all significantly increased under low temperature stress.Several inhibitors could impact the anthocyanin biosynthesis in the low temperature level such as photosynthetic electron transport chain inhibitors DCMU and DBMIB,NADPH oxidase inhibitor DPI,glycolate oxidase inhibitor oxalic acid,peroxidase inhibitor Na N3 and superoxide dismutase inhibitor DDC.Different inhibitors decreased the anthocyanin,H2O2,MDA,Evans blue content and oxidase(SOD,POD,PAO,GO)activity and also the anthocyanin related genes expression(PAL,CHS,F3 H,ANS).While different inhibitors promoted the leaf net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO2 concentration(Ci),and transpiration rate(Tr)equivalent.Theses above showed that the chloroplasts,peroxisomes,apoplast,plasma membrane and cell wall had different level contribution for H2O2 production in the Begonia leaf under low temperature stress.(3)Transcriptome sequencing was completed in three samples with the technology of high-throughput sequencing and a total of 94,880 unigenes were assembled,of which 54,799 sequences were noted in NR,COG,GO and Swiss-Prot database.In CK vs LT and CK vs HL group,1712 sequences were annotated to the COG database and then divided into 22 categories,respectively;3261 sequences were annotated to the GO database and then divided into 36 subgroup,respectively;With the FPKM value level,there were 4156 and633 different expression genes in CK vs LT and CK vs HL group,respectively.Among the above different expression genes,there were 12 genes known as anthocyanin biosynthetic function after comparing with similar sequences in other plant and were all up-regulated.