黄化变异茶树石门黄叶理化分析及茶氨酸相关基因表达研究

黄化变异是茶树较为常见的叶色变异现象,黄化茶树的特征性化学成分含量会发生较大变化,其中氨基酸含量显著增加,研究此现象形成的原因有助于揭示叶色与氨基酸代谢的相关性。本研究以石门地区自然黄化变异茶树为材料,对其全黄、全绿和黄绿叶片进行叶绿体超微结构分析和主要生化成分检测,采用实时荧光定量PCR方法检测茶氨酸生物合成相关基因（TS,CsGS1,CsGS2）在不同叶色间的表达水平并分析它们与茶氨酸含量的相关性。结果表明：（1）与绿叶相比,黄化叶的叶绿体结构存在异常,主要表现为类囊体膜结构不清晰;（2）生物碱含量由高到低分别为黄叶、绿叶、黄绿叶,组间差异显著;（3）没食子酸、总儿茶素含量在绿叶中最高,在其他两组间无显著差异,多种儿茶素组分含量随叶片转绿而提高,但EC与叶片黄化程度呈正相关;（4）氨基酸和茶氨酸含量变化趋势与叶片黄化趋势相同;（5）TS基因和CsGS1基因在绿叶中表达量最高,在黄绿色叶片中表达量最低,CsGS2基因在全黄叶片中表达量最高;（6）茶氨酸含量与TS、CsGS1、CsGS2基因表达量均无显著相关性。可见,黄化茶树叶片的叶绿体结构异常,其物质代谢会受到影响,氨基酸分解被抑制,并富集在黄化叶中。

Research of Theanine-related Genes Expressed in Etiolated Tea Plant(Camellia Sinensis)

Etiolation is a common morphological variation in tea plants.In those mutants,the contents of the characteristic metabolites change greatly and amino acids are highly accumulated.Studying the reasons of these changes can help to reveal the relationship between leaf color variation and amino acid metabolism.In this study,an etiolated tea plant,which was found accidentally in Shimen area,was used as the research material.As a leaf-color mutant,it has three different colored leaves:yellow,green and yellow-green.The ultrastructure of the chloroplasts,the contents of characteristic metabolites,the expression levels of theanine-related genes(TS,CsGS1,CsGS2)and the correlation between the expression levels and theanine in different leaves were studied.The results show:(1)the chloroplast structure of the yellow leaves was abnormal,which mainly presented as the blurry structure of the thylakoid membrane.(2)the alkaloid contents reduced from yellow,green to yellow-green leaves with significant differences.(3)gallic acid and total catechin contents were the highest in green leaves,and there was no significant difference between the other two groups.The contents of multiple catechins increased as the leaves turned green,but the contents of EC were positively related to the etiolation.(4)the contents of amino acids and theanine increased as the leaves turned yellow.(5)TS and CsGS1 showed the highest expressions in green leaves but the lowest expressions in yellow-green leaves.While CsGS2 exhibited the highest expression in yellow leaves.(6)high theanine content was not related to the expressions of TS,CsGS1 and CsGS2.In summary,the chloroplast structure of etiolated tea plant is abnormal,the metabolism is affected,the amino acid decomposition is inhibited in the etiolated leaves,which result in the enrichment of amino acids.