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

研究了铝对茶树根系生长的促进作用。结果表明：1.铝处理对茶树扦插苗、离体茶细胞和幼苗的生长有促进作用，但与磷水平无关; 2.铝处理降低了茶树叶片木质素含量和细胞壁酚类物质含量，并对酚类物质代谢关键酶苯丙氨酸解氨酶（PAL）和过氧化物酶（PO）活性进行了测定。Al处理显著降低了插穗和幼苗根系PAL活性，降低了可溶性、离子结合和共价结合PO活性。3.研究了Al处理对膜脂过氧化、H_2O_2含量和抗氧化酶（CAT、APX和SOD）活性的影响。铝处理降低了茶插穗、茶苗和离体茶细胞膜脂过氧化和H_2O_2含量。Al处理提高了茶树体内CAT、APX和SOD的活性，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含量的降低是由APX和/或低分子抗氧化物质共同作用的结果。NaCl的影响也在茶细胞中进行了检查。5.从铝对氧化胁迫的缓解和对酚类物质代谢的影响来看，铝对茶树生长的促进作用可能与维持细胞膜稳定性和延缓衰老有关。

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.