Studies on internal detoxification mechanisms for aluminum of woody plants

1.铝对茶树和桉树生长及矿物组成的影响在0.4 mM含铝（Al）的营养液（pH 4.2）中栽培数月后，茶树（Camellia sinensis L.）和桉树（eucalyptus camaldulensis Dehnh）的生长没有受到抑制，说明这两种植物对铝都具有耐受性。与茶树在茎部积累铝相比，桉树只在根部积累铝。利用^<27>Al- nmr，表明在根尖和细胞液中存在草酸铝配合物。在桉树的根中，有可能存在柠檬酸铝配合物。在茶叶的^<27>的Al-NMR谱中，存在与al -儿茶素络合物不同的化学位移信号。随着铝含量的增加，茶根中柠檬酸盐和草酸盐的含量也随之增加。在桉树根系中，Al诱导枸橼酸合成酶的激活和枸橼酸代谢酶活性的抑制，导致枸橼酸含量增加。茶根中草酸盐的分泌量随着Al的添加而增加。Al对茶叶和桉树培养细胞的影响在B5 （pH 4.2）培养基中，Al对培养的茶叶细胞生长无影响。培养的桉树细胞从叶子中提取，并继续检查传代培养的培养基条件。与内部铝解毒机制相关的蛋白质和基因的检测。结果表明，在Al存在的情况下，茶根RNA水平诱导过氧化氢酶和抗坏血酸预氧化酶的表达，这表明草酸盐和柠檬酸盐分别在茶树和桉树耐Al机制中起核心作用。

1.Effects of aluminum on the growth and mineral composition of tea plants and eucalyptusThe growth of tea plants (Camellia sinensis L.) and eucalyptus (Eucalyptus camaldulensis Dehnh), cultivated in the nutrient solution (pH 4.2) containing aluminum (Al) at 0.4 mM for several months, were not suppressed, suggesting that both plant species were tolerant to Al. Comparing to tea plants accumulated Al in the shoots, eucalyptus accumulated Al only in the roots.2.The form of Al after uptakeUsing ^<27>Al-NMR, it was shown the presence of Al-oxalate complexes in root tips and the cell saps. In roots of eucalyptus, it was suggested the possibility the presence of Al-citrate complexes. In ^<27>Al-NMR spectra of tea leaves, there were signals of which chemical shifts were not identical to Al-cathechins complexes.3.Accumulation and secretion of Al chelating compounds of rootsAlong with the increase of Al contents, the contents of citrate and oxalate in tea roots were increased. In the roots of eucalyptus, Al induced the stimulation of citrate synthase and the suppression of enzyme activities in citrate metabolism, resulting in the increase of citrate content. The amount of oxalate secreted from tea roots was increased with Al in the medium.4.Effects of Al on the cultured cells of tea and eucalyptusThe growth of cultured tea cells was not influenced with Al in B5 medium (pH 4.2). The cultured eucalyptus cells were derived from leaves and were continued to examine the conditions of medium for subculture.5.Examination of proteins and genes correlated to the internal Al detoxifying mechanism.It was shown in RNA levels of tea roots that the expression of catalase and ascorbate preoxidase were induced in the presence of Al.These results suggested that oxalate and citrate were central roles in Al tolerant mechanisms of tea plant and eucalyptus, respectively.