Sucrose Metabolism And Its Role In Rubber Biosynthesis In Hevea Brasiliensis

Natural rubber is a kind of renewable resource with vital importance in industry in China.It is also one of the main sources of income for tropic farmers. Rubber biosynthesis and its regulation are the theoretical basis for genetic improvement of rubber tree, which is also one of the hot spots in this research. Much progress has been made on the biochemical and molecular pathway of rubber biosynthesis and its regulation. From cellular perspective, rubber biosynthesis is the result of coordinated biochemical conversion in which sucrose metabolism played an important role. In this study, we used a new method to identify rubber tree varieties. We also studied the gene expression and enzyme activity as well as the intermediate metabolites in the latex to reveal the relationship between sugar metabolism and rubber biosynthesis. The results are as follows:1.PCR amplification with 16 gene specific primer pairs were used to amplify the genomic DNA of different rubber tree varieties. The polymorphisms of the bands as well as the SNP of SRPP successfully identified 21 rubber tree clones. This method can be effectively used to identify rubber tree varieties during the field experiment.2.Two rubber tree varieties with different latex yield, eg. RRIM 600 and PR 107 were chosen to study the sucrose and its intermediates contents as well as the enzyme activity in the process in the latex, the results showed that sucrose and glucose as well as the soluble sugar in the latex was higher in PR107 when compared with RRIM 600, while the activity of invertase was lower. Moreover, the expression of other sucrose metabolism related genes (F2KP?FBPase?cpFBPase?Nadp-Me)was higher in latex of RRIM 600. Similar results were detected using 4 other rubber tree varieties, and the results indicated that lower content of sucrose and glucose in latex might lead to the higher latex yield.3. High through-put de novo transcriptome analysis were used to detect the overall gene expression profile between latex from RRIM 600 and PR 107 in December and July,Q-RT-PCR were used the verify the transcriptome data. The result showed that the expression of genes in rubber biosynthesis is higher in latex of RRIM 600 when compared with PR107. At the same time,sucrose metabolism genes (SS,Inv,SUT6,PFK5 and UDPG transferase) were also upregulated, these results indicated that overall speaking, sucrose metabolism affected the rubber biosynthesis. On the other hand,gene related to ethylene induction, antioxidative enzymewere, regulatory factors jasmonate(JAZ) and transcription factor WRKY were also upregulated in latex of RRIM600. This means the differences of sucrose metabolism can lead to the differences of latex yield by influencing the ways of other rubber biosynthesis.All results above indicated that sucrose metabolism in rubber can influence rubber biosynthesis by many kinds of ways.