The Phylogenetic Analysis Of The Key Genes In Sucrose Metablism And The Sugar Transporter In Saccharum

Sugarcane (Saccharum spp.) is a large, perennial, tropical or subtropical cropgrown worldwide. Sugarcane is an economically important crop contributing about80%and40%to the worldsugar and ethanol production, respectively. Energycane/sugarcane is a first generation biofuel crop used for ethanol production as analternative source of energy.Modern Saccharum is a complex genus of tall perennial grasses that are highlypolyploid. Morphology, chromosome number, and geographic distribution havetraditionally been used for taxonomic classification. Differentially expressed genes inkey pathways affecting sugar production could be good candidates for sugarcaneimprovement using transgenic approach. Genomic technologies will facilitate andexpedite the discoveries of target genes that will benefit sugarcane farmers and thebiofuel industry. In recent years, the sorghum allied with the sugarcane has beencompleted the entire genome sequencing, provided a possible of the precisecomparison of the genome for sugarcane research. And at the same time,as arepresentative of Illumina and Roche Company,the second generation high energysequencing technology provides the platform of the complex plants genomesequencing。This study is based on the Comparative Genomics and second generationsequencing technology, analysing the gene related to the sugar metabolism andtransport in the sugarcane, aims at revealing the sugar accumulation mechanism of thesugarcane,as well as lays the basic Molecular Biology foundation on the breeding ofhigh sugar genetic engineering. The main contents are as follows:Firstly, towards understanding the molecular basis of high sucrose accumulation, we have annotated and analyzed ATP-dependent phosphofructokinase (PFK) genefamily, FRK and sugar transporters. In this study, based on the sorghum, Arabidopsis,rice genome and sugarcane EST database,10and4gene members in PFK and FRK,52genes of8gene families from sugar transporter were annotated and further verifiedby PCR using sugarcane genomic DNA.Secondly, we discussed these genes in evolution and the molecular characteristicsof production deduced. The results showed that there are signifacant differences innumbers of FRK, PFK and sugar transportproteins found in both monocots and dicots.Unrooted phylogenetic tree was constructed with the deduced protein sequences ofPFKs, FRKs and sugar transporters that were from the assembly of cDNA library ofsugarcane and other plants. The results of PFKs showed that gene duplication eventsand/or the retention rate after genome wide or segmental duplications occurred inhigher frequency in monocots than in dicots, and the genes in subgroup II of group IIIwere likely originated from recent duplication events, include ScPFK7, ScPFK8,ScPFK9and ScPFK10.Thirdly, Quantitative RT-PCR was performed to investigate the gene expressionof10PFK genes,4FRK genes and31sugar transporters in the five tissues of threeSaccharum species, including two developmental stages in leaves and three in stems.Of the PFK family members in sugarcane, ScPFK7,8and9appeared to be theprimary isoforms based on the obvious difference expression of these three genes. Thegenes in monocot specific subgroup II of group III, ScPFK7,8and9, showedvariation among the three Saccharum species, suggesting potential functionalredundancy. ScPFK8had lower expression level in S. officinarum than in the othertwo species, suggesting negative regulation of sucrose metabolism, which might havecontributed to the high sugar content of S. officinarum.The result of31sugar transporters in the five tissues of three Saccharum speciesshowed, ScSUC/SUT5and ScSTP/HXT9had higher expression level in S. spontaneumthan other species, ScSFP7had lower expression level in S. spontaneum. Two ScAZT/MSSP genes have highest expression level in three species.Fourthly, SNPs and Haplotype sequence analysis for4FRK genes within threeSaccharum species genome was researched in a target genomic region. The averageSNP frequency was one SNP per73bp,38bp, and45bp in S. officinarum, S.robustom, and S. spontanuem respectively. The average shared SNP is22between S.officinarum and S. robustom,15between S. officinarum and S. spontanuem, and31between S. robustom and S. spontanuem. We identified27,27, and24haplotypesfrom the four ScFRK genes in S. officinarum, S. robustom, and S. spontanuemrespectively.