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
茶通常由茶樹的新芽(茶樹)制成，是最受歡迎的健康飲料之一。新芽的嫩度對優(yōu)質(zhì)茶葉的生產(chǎn)起著至關(guān)重要的作用;然而，影響茶葉新芽嫩度的因素尚未得到廣泛的研究。本研究通過甲苯胺藍染色對兩個品種(‘黃金芽’和‘玉金香’)新芽的纖維素含量進行表征，發(fā)現(xiàn)纖維素的積累與新芽(包括葉和莖)的嫩度呈負相關(guān)。我們進一步發(fā)現(xiàn)，隨著莖稈成熟度的增加，具有次生細胞壁的細胞數(shù)量和細胞厚度增加。由于纖維素是SCW中最豐富的聚合物，接下來我們通過與擬南芥AtCesAs的同源比對，鑒定出3個纖維素合成酶CsCesAs, CsCesA4, 7和8A。系統(tǒng)發(fā)育分析表明，這些蛋白具有密切的親緣關(guān)系。結(jié)果表明，3個CsCesAs的基因表達量均與新枝的成熟度和纖維素含量呈正相關(guān)。因此，我們的數(shù)據(jù)表明，纖維素的積累，特別是SCWs，與茶樹新芽的嫩度呈負相關(guān)。
來源：茶葉江湖
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