Analysis of factors of growth stimulation by aluminum in roots of tea plants

本文研究了铝（Al）对茶树根系生长的促进作用。结果总结如下：在不同磷水平下，铝均能促进茶树扦插生根、培养的茶树细胞和茶树幼苗的生长。通过测定酚代谢关键酶苯丙氨酸-氨解酶（PAL）活性和过氧化物酶（PO）活性，降低了木质素含量和壁结合酚含量。Al明显降低了有根插枝和幼苗根系的PAL活性，降低了所有样品中可溶性、离子结合和共价结合PO的活性。考察了铝对脂质过氧化、H_2O_2含量及抗氧化酶（过氧化氢酶CAT、抗坏血酸过氧化物酶APX和超氧化物歧化酶SOD）活性的影响。铝处理降低了茶根插条、茶苗和培养细胞的脂质过氧化和H_2O_2含量。Al处理提高了茶树CAT、APX和SOD的活性，CAT抑制剂4.3- at完全抑制了CAT的活性，但对H_2O_2含量没有影响。认为铝处理中H_2O_2含量的还原是由APX和/或低分子抗氧化物质完成的。同时还考察了NaCl对茶细胞的影响。脂质过氧化增加，H_2O_2含量增加。从降低氧化应激和Al对酚类代谢的影响的结果推测，维持膜稳定性和延缓衰老是Al处理与未处理茶树生长刺激或生长差异的因素。

In this study, stimulatory effect of aluminum (Al) on the growth of roots of tea plants were studied. Follows are summary of the results:1.The growth of rooted cuttings, cultured tea cells and seedlings of tea plants were stimulated by Al, irrespective of phosphate levels.2.Lignin content, wall-bound phenolics contents were reduced by Al. Key enzyme of phenolic metabolism, phenylalanine-ammonia lyase (PAL) activity, and peroxidase (PO) activity were determined. PAL activity of roots of rooted cuttings and seedlings were clearly decreased by Al. The activity of soluble, ionically-bound, and covalently-bound PO also decreased by Al in all samples.3.Effects of Al on lipid peroxidation, H_2O_2 contents, and on the activities of antioxidant enzymes (catalase : CAT, ascorbic acid peroxidase : APX and superoxide dismutase : SOD) were examined. Lipid peroxidation and H_2O_2 contents were decreased by Al treatment in tea rooted cuttings, tea seedlings and cultured tea cells. The activities of CAT, APX and SOD were increased by Al treatment in tea plants.4.3-AT, an inhibitor of CAT, inhibited the activity of CAT completely, but H_2O_2 contents were not affected. It is considered that the reduction of H_2O_2 contents in Al treatment is carried out by APX and/or low molecular antioxidative substances. Effect of NaCl was also examined in tea cells. Increase of lipid peroxidation and the increase of H_2O_2 contents were observed.5.From the results in the reduction of oxidative stress and the effect of Al on phenolic metabolism, the maintenance of membrane stability and retardation of aging were guessed as the factors for growth stimulation or growth differences between Al treated and non-Al treated tea plants.