Studies on internal detoxification mechanisms for aluminum of woody plants

1.铝对茶树和桉树生长及矿质元素组成的影响而桉树（Eucalyptus camaldulensis Dehnh）在0.4mM铝（Al）的营养液（pH 4.2）中培养几个月后，铝的积累没有受到抑制，表明两种植物都对铝有耐受性。与茶树相比，桉树只在根部积累铝<27>。桉树根中可能存在柠檬酸铝络合物。茶树<27>叶片的~ 1H-Al-NMR谱中出现了与Al-cathechins络合物不同的化学位移信号。3.根系中铝螯合物的积累与分泌随着铝含量的增加，茶树根系中柠檬酸盐和草酸盐的含量也随之增加。在桉树根系中，铝诱导柠檬酸合成酶的激活和柠檬酸代谢酶活性的抑制，导致柠檬酸含量的增加。铝对茶树和桉树培养细胞的影响在B5培养基（pH4.2）中，铝对茶树培养细胞的生长没有影响。5.茶树体内铝解毒机制相关蛋白和基因的检测，在RNA水平上，铝诱导茶树根系过氧化氢酶和抗坏血酸过氧化物酶的表达，说明草酸和柠檬酸在茶树耐铝机制中起着重要作用和桉树。

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.