小粒咖啡树咖啡碱合成途径中CaXMT1、CaDXMT1、CCS1表达差异及其与咖啡碱含量的相关性  

Correlation Between Genes Expression Levels of CaXMT1,CaDXMT1,CCS1 in Caffeine Biosynthesis Pathways and Caffeine Content in Coffee arabica

作　　者：李芬 李丽江 徐丹旎 陈春林[2] 王玮 李梅 LI Fen;LI Li-jiang;XU Dan-ni;CHEN Chun-lin;WANG Wei;LI Mei(College of Tea(Pu’er),West Yunnan University of Applied Sciences,Pu’er 665000;Tea Research Institute,Yunnan Academy of Agricultural Science,Menghai 666201)

机构地区：[1]滇西应用技术大学普洱茶学院,普洱665000 [2]云南省农业科学院茶叶研究所,勐海666201

出　　处：《生物技术通报》2019年第10期95-101,共7页Biotechnology Bulletin

基　　金：云南省应用基础研究计划项目(2017FD023)

摘　　要：探索咖啡碱合成途径中3个关键酶基因CaXMT1、CaDXMT1和CCS1表达与咖啡碱合成的相关性,探讨小粒种咖啡豆中咖啡碱合成机理,为咖啡树的育种提供理论依据。利用高效液相色谱(HPLC)及实时荧光定量PCR(qRT-PCR)仪分别测定小粒种咖啡植株不同组织不同发育时期咖啡碱含量和CaXMT1、CaDXMT1、CCS1的mRNA相对表达量,并进行相关性分析。结果表明,不同组织不同发育时期咖啡碱含量由高到低依次为嫩叶>幼果>成熟鲜果>成熟叶片,且幼龄组织中的咖啡碱含量皆显著高于成熟期(P<0.01)。CaXMT1在幼龄组织中的相对表达量显著低于成熟期(P<0.01),而CaDXMT1和CCS1相对表达量在同一组织不同发育时期中差异不显著。CaXMT1在幼果中的相对表达量与咖啡碱的含量呈显著负相关(R2=0.93,P<0.01),CaDXMT1和CCS1在不同组织不同发育时期中的相对表达量与咖啡碱含量相关性不明显。咖啡碱的合成途径是一个复杂的过程,关键酶基因在不同组织不同时期的表达量及其与咖啡碱合成的相关性差异,可能与酶的特性有关。This work aims at exploring the correlation between expression levels of 3 key enzyme genes CaXMT1,CaDXMT1,CCS1 and caffeine synthesis in the biosynthetic pathways of caffeine in coffee(Coffee arabica)plants,as well as studying the synthetic mechanism of caffeine,thus providing theoretical evidences for the breeding of coffee trees.HPLC was used to measure the caffeine contents in the different tissues of coffee(C.arabica)plants at different developmental stages,as well as PCR(qRT-PCR)to measure the mRNA levels of CaXMT1,CaDXMT1 and CCS1,and the correlations between genes expression levels and caffeine content were conducted.The results suggested that caffeine content in different tissues presented the order as tender leaves>immature fruits>mature fruits>mature leaves.The caffeine content in immature tissues was significantly higher than that in mature ones(P<0.01).Gene expression levels of CaXMT1 in the immature tissues was markedly less than that in the mature tissues(P<0.01),whereas,there was no significant difference among the relative expressions CaDXMT1 and CCS1 in different development stages at the same tissue.Gene expression levels of CaXMT1 and caffeine content in immature fruits demonstrated a significantly negative correlation(R2=0.93,P<0.01),while,there was no significant correlation between the relative expressions of CaDXMT1,CCS1 and caffeine content in different tissues at different development stages.The biosynthetic pathway of caffeine in coffee(C.arabica)plants is a very complex process,the expression levels of key enzyme genes and their correlations with the caffeine content vary,which might result from their enzymatic properties.

关 键 词：小粒咖啡树 咖啡碱 CCS1 CaXMT1 CaDXMT1 基因表达 相关性 

分 类 号：TS2[轻工技术与工程—食品科学与工程]