铝在茶树叶片亚细胞中的分布及其与细胞壁的结合研究

Aluminum subcellular distribution and its combining characreristics with cell wall in tea leaves

茶树是一种非常典型的聚铝植物,主要富集在叶片中。为了解析茶树叶片聚铝的特性,以高铝品种农抗早和低铝品种平阳特早的成熟叶片为材料,分析了茶树叶片中铝的亚细胞分布及与细胞壁可能的结合方式。结果表明,两个品种(农抗早、平阳特早)叶片中的铝主要分布在细胞壁中(46.2%~54.9%),其次是细胞核和叶绿体(24.2%~31.2%)。在细胞壁组分中,果胶是细胞壁富集铝的主要组分,占细胞壁中铝含量的60.1%~79.0%。细胞壁经甲基改性处理和酯化改性处理均显著降低了铝含量,而纤维素酶和果胶酶酶解处理对细胞壁中铝含量影响较小,说明细胞壁中的羧基和氨基在结合铝上起着关键性作用,而糖分子链长短对铝的结合作用不明显。因此,茶树叶片细胞壁是铝聚集的主要部位,阻挡了铝进一步进入细胞内部,降低了铝的毒害作用;铝很可能以氢键的形式与细胞壁中羧基和氨基结合而被固定在细胞壁中。

Tea tree(Camellia sinensis)is a very typical aluminium(Al)concentrating plant,which is mainly enriched in the leaves.In order to analyze the characteristics of Al content in tea leaves,this paper explored the accumulation characteristics of Al in tea leaves using mature leaves of the high-Al variety Nongkangzao and the low-Al variety Pingyangtezao as materials,and analyzed the subcellular distribution of Al in tea leaves and the possible binding mode with the cell wall.The results showed that Al in the leaves of the two varieties(Nongkangzao and Pingyangtezao)was mainly distributed in the cell wall(46.2%-54.9%),and to a less extent in the nucleus and chloroplasts(24.2%-31.2%).In the cell wall fractions,pectin was the main Al-enriched component of the cell wall,accounting for 60.1%-79.0%of the Al content in the cell wall.Both methyl-modified and esterified treatments significantly reduced the Al content of the cell wall,while the cellulase and pectinase enzymatic treatments had less effect on the Al content of the cell wall,suggesting that the-COOH and-NH 2 in the cell wall play a key role in binding Al,while the length of the sugar molecule chains had no significant effect on the Al binding.Therefore,the cell wall of tea leaves is the main location where Al accumulates,preventing it from entering further into the cell interior and reducing its toxic effects;Al is most probably bound to the carboxyl and amino groups in the cell wall in the form of a hydrogen bond and is immobilised in the cell wall.