The Study Of Key Genes On Flowering And Fruit Quality From Ziziphus Jujuba Based On Transcriptome Sequencing

Jujube(Ziziphus jujuba Mill.)is a unique fruit tree species in China,with high nutritional and economic value,and the fruit has a variety of nutrients.The development and amount of flowers carries huge implications on the yield of jujube,the fruit quality also affect its economic value directly.Ziziphus jujuba cv.'Zhongqiusucui' is a good variety which was breeded for growing in Hunan province in recent years.In this research,transcriptome sequencing was conducted on flowers,fruits and bearing shoots of elite Z.jujuba cv.'Zhongqiusucui' by using Illumina-based RNA-seq technology,based on that the key genes of flowering and fruit quality were studied by real-time quantitative PCR,and analyzed the correlation between the key genes of fruit quality and the physiological indexes of the formation of fruit at the same time.This study laid a theoretical basis for revealing the flowering mechanism and formation of fruit quality.The main results were as follows:(1)The transcriptome analysis of Z.jujuba.There were 2 098 231 contigs,34587 unigenes,34 463 ORFs and 12 624 microsatellites obtained in the transcriptome sequencing data of fruits,flowers,and bearing shoots of Z.jujuba,the length of most unigene sequences accounting to 87.46 percentage of all unigenes were distributed between 200bp and 2 000 bp.There were 23 303 unigenes got annotated,23 271,16460,8 043 and 5 181 unigenes could be matched in the public database of Nr,Swiss-Prot,COG,KEGG respectively.The mononucleotide repeat microsatellites were the most which is the preponderance among Z.jujuba,second is the dinucleotide repeat microsatellites(3 335,26.42%).Identified 58 important flowering-relate genes(FT,FLC,AGL6,SOCl,SVP,etc),and 101 important genes of fruit quality(DHAR,MDHAR4,MDHAR6,SS,SPS,etc)in the transcriptome of Z.jujuba.(2)The expression analysis of flowering related genes in Z.jujuba.Based on the transcriptome of Z.jujuba,the reference gene EF1? was screened through PCR and real-time quantitative qPCR technology.To analyse the expression of 20 flowering related genes which were selected,the expression of FT gene increased with the development of flower gradually;AGL6 and VIP1 gene were mainly expressed in the flower,and the expression was the highest in the big bud and half-blooming flower respectively;VIN3 and LHY1 gene were mainly expressed in vegetative organs and great expressed in the root and bearing shoots respectively;COL2 and COL4 gene were expressed in half-blooming flower and full-blooming flower respectively and they were also expressed in vegetative organs;the expression trend of ELF4 gene in the developmental process of the flower was "rise-decline-rise";the highest expression of PHYA and PHYC gene were in full-blooming flower,PHYB gene was in the squaring stage;the expression of FLC,PFT1 and GAI1 gene were the highest in the big bud;the highest expression of CAB,CAB 13,ERF and ERF 12 gene were in full-blooming flower;SVP and AGL20 gene were strongly expressed in bearing shoots.(3)The expression analysis of fruit quality related genes in Z.jujuba.To analyse the expression of 34 fruit quality related genes which were selected,the related genes of sugar accumulation and sucrose-metabolizing in the fruit,as SS6,?-MAN,PNI1,UGDHL1,UGDH,SPS2,HXK1 gene were expressed higher in the fruit of 10,40,90 and 110 days after blooming respectively;the related genes of VC synthesis and metabolism,as DHAR,MDHAR4,APX,GPIL,MDHAR6 were expressed higher in the fruit of 25,40 and 110 days after blooming respectively;the related genes of aroma synthesis,as CAD1,O-MT,ADHL6,ADHL7,MTs,SAMT,co-6FAD,LOX were expressed higher in the fruit of 10,25,40 and 110 days after blooming respectively;the related genes of fruit softening,as SHP,SIP,POD3,PE,PG,EXP were expressed higher in the fruit of 25,40,90 and 110 days after blooming respectively.The expression of AACT,HXK1,MDHAR6,GPIL,HXK1,SPS2,PG,SHP and LOX were significantly higher in dehiscent fruit than other development stages of fruit,it is speculated that these genes could be concerned with dehiscent fruit.(4)The correlation analysis between the key genes of fruit quality and the the physiological indexes of the formation of fruit.The trends of the fruit inclusion during the development of fruit were as follows:VC content reduced gradually with the fruit maturation;an overall rise in the content of soluble sugar,reducing sugar,starch and soluble solids;the trend of titratable acid content decreased first and then rise slowly;the soluble protein showed a tendency to fluctuate with the development of fruit.The correlation analysis between the expression level of 34 genes and fruit inclusion shows that,the expression of AACT,DHAR,MDHAR4,MDHAR6,GPIL,HXK1,LOX,SPS2,UGDHL and co-6FAD were correlated significantly with the VC content at 0.01 level;the correlation of the expression of UGDHL,co-6FAD,EXP,POD7 and a-MAN with the content of soluble sugar and reducing sugar were very high;the correlation coefficient for the expression of UGDHL,EXP and POD7 were correlated significantly with the starch content at 0.01 level;the expression of DHAR,GIPL,LOX,MDHAR4 and MDHAR6 were correlated significantly with the soluble protein content at 0.05 level;the expression of EXP,PME and POD7 were correlated significantly with the titratable acid content at 0.01 level;the expression of EXP and POD7 were also correlated significantly with soluble solid.