茶树次生细胞壁的纤维素积累与新芽嫩度呈负相关

Abstract

Tea, which is usually made from the new shoots of tea plants (Camellia sinensis), is one of the most popular and healthy beverages. The tenderness of new shoots plays a critical role in the production of high-quality tea; however, the factors affecting the tenderness of the new shoots of tea have not been extensively studied. Here, we show that cellulose accumulation is negatively correlated with the tenderness of new shoots, including leaves and stems, by characterizing the cellulose content and vizualising cellulose in the new shoots of two cultivars (‘Huangjinya’ and ‘Yujinxiang’) via toluidine blue staining. We further found that the number of cells with secondary cell walls (SCWs) and the thickness of SCWs increased with the maturity degree of stems in both cultivars. Because cellulose is the most abundant polymer in SCW, we next identified three cellulose synthase CsCesAs, CsCesA4, 7, and 8A through homologous alignment with Arabidopsis AtCesAs. Protein sequence analysis revealed that these proteins were closely related based on the phylogenetic analysis. We finally showed that the gene expression of the three CsCesAs was positively correlated with the maturity degree and cellulose content of the new shoots. Thus, our data suggest that cellulose accumulation, especially in the SCWs, is negatively correlated with the tenderness of new shoots in tea plants.

摘要

茶通常由茶树的新芽(茶树)制成，是最受欢迎的健康饮料之一。新芽的嫩度对优质茶叶的生产起着至关重要的作用;然而，影响茶叶新芽嫩度的因素尚未得到广泛的研究。本研究通过甲苯胺蓝染色对两个品种(‘黄金芽’和‘玉金香’)新芽的纤维素含量进行表征，发现纤维素的积累与新芽(包括叶和茎)的嫩度呈负相关。我们进一步发现，随着茎秆成熟度的增加，具有次生细胞壁的细胞数量和细胞厚度增加。由于纤维素是SCW中最丰富的聚合物，接下来我们通过与拟南芥AtCesAs的同源比对，鉴定出3个纤维素合成酶CsCesAs, CsCesA4, 7和8A。系统发育分析表明，这些蛋白具有密切的亲缘关系。结果表明，3个CsCesAs的基因表达量均与新枝的成熟度和纤维素含量呈正相关。因此，我们的数据表明，纤维素的积累，特别是SCWs，与茶树新芽的嫩度呈负相关。

来源：茶叶江湖

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