Studies on internal detoxification mechanisms for aluminum of woody plants

1.铝对茶树和桉树生长及矿物质组成的影响和桉树(Eucalyptus Camalulensis Dehnh)在含铝(Al)0.4 mm的营养液(pH 4.2)中培养数月后未受到抑制，表明这两种植物对铝都有耐性。与茶树在地上部积累的铝相比，桉树只在根部积累铝。2.吸收后铝的形态。核磁共振分析表明，在根尖和细胞液中存在草酸铝络合物。在桉树的根中，可能存在柠檬酸铝络合物。茶叶&lt；27&gt；Al-核磁共振谱中有与铝离子络合物不同的化学位移信号。3.根中铝络合物的积累和分泌随着铝含量的增加，茶树根中柠檬酸和草酸的含量增加。在桉树根部，铝诱导柠檬酸合成酶活性升高，抑制柠檬酸代谢酶的活性，导致柠檬酸含量增加。4.铝对茶树和桉树培养细胞的影响在B5(pH 4.2)中，铝不影响茶树细胞的生长。5.与体内铝解毒机制相关的蛋白质和基因的检测。在茶树根的RNA水平上，发现铝诱导过氧化氢酶和抗坏血酸前氧化酶的表达。这些结果表明，草酸和柠檬酸分别在茶树和桉树的耐铝机制中起着中心作用。

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.