The Relationship Between Cucumber Astrengency Form And Catechins Metabolism, And The Study Of Molecular Basis

Cucumber (Cucumis sativus L.) is an agriculturally and economically important vegetable crop worldwide. There are different degrees astringency in cucumber. The material basis of the astringent formation is derived from the metabolism of catechin. However, astringent substance has certain scavenging free radicals, anti-cancer, anti-aging, anti-coronary heart disease and anti-bacteria etc. But the catechins content and species identification and molecular basis of metabolic research have rarely been reported in cucumber fruit.In this study, High Performance Liquid Chromatography (HPLC) was used to research catechins content and catechins species identification in the cucumber fruit which has developed 0-9d in 'YB' and 'YN'. Their comprehensive are significant differences. Using qRT-PCR technology researches the relative expression levels for 'YB' and 'YN'(0-9d) two varieties of phenylalanine metabolic pathway 9 structure gene and 3 transcription factor MYB gene. The main results show:1. We can detect GC, C, EC and EGCG four kinds of catechin in cucumber fruit. Compaired to GC, C and EGCG, the content of EC were most low; GC content in cucumber fruit is higher. The cucumber fruit astringency mainly comes from the skin. GC,EGCG and total catechin content presents downtrend with fruit development, which causes heavy astringency in the early development of cucumber fruit.2. The GC content of 'YB' is significant higher than the GC content of 'YN' in spring and autumn. The GC content of same variety is no obvious difference in the spring and autumn. This may suggest that the biosynthesis of astringent substances is less affected by environment and shows genetic stability.3. The structural gene DFR and LAR have a significant influence in the synthesis of astringency in cucumber fruit. The relative expression of the structure gene DFR with GC, EGCG and total catechins was significant positive correlation; LAR showed a significant positive correlation with C.4. The transcription factor MYB3 and MYB1 have a significant influence in the synthesis of astringency in cucumber fruit. The relative expression of transcription factor MYB3 showed a significant negative correlation with the content of GC?EGCG and total catechins.5. There was a significant negative correlation between MYB3 and DFR. There was a significant positive correlation between MYB1 and DFR. This indicates that the MYB3 may affect the synthesis of catechins through negative regulation of DFR and MYB1 may affect the synthesis of catechins through positive regulation of DFR.