油茶根尖铝累积及其对酚代谢和抗氧化相关指标的影响

Aluminum accumulation and its effects on contents of substances involved in phenols metabolism and antioxidation in root tips of Camellia oleifera

以油茶‘华金’(Camellia oleifera ‘Huajin’)扦插苗为试验材料,设不加铝和1 mmol·L-1铝处理4、24、48、100、196 h根尖前2 cm,测定根尖铝含量、酚代谢物以及抗氧化相关指标。结果表明:根尖铝含量随着铝处理时间增加而增加,细胞壁铝含量为根尖总铝含量的73.10%,细胞壁上的果胶和半纤维素1 (HC1)有较强的铝累积吸附能力;铝诱导苯丙氨酸裂解酶(PAL)活性提高,可溶性酚和细胞壁结合态酚含量提高,多酚氧化酶(PPO)以及共价结合态过氧化物酶(CPO)活性降低;铝添加提高了超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性,降低了H2O2和丙二醛(MDA)含量;铝供应提高了可溶性糖、可溶性蛋白和游离脯氨酸含量。该研究表明油茶根尖细胞壁果胶和HC1对铝的强吸附累积能力降低了铝毒性;适宜的外源铝能提高酚类物质含量和降低CPO活性,有利于增强抗逆性和降低细胞壁木质化速度;活性氧清除能力以及渗透调节能力的增强有利于细胞内环境的稳定。适宜浓度外源铝供应条件下多种生理响应机制协同促进了油茶根尖伸长。

Cutting seedlings of Camellia oleifera ‘Huajin’ were treated with 0 or 1 mmol·L-1 aluminum(Al) and the contents of Al and substances involved in phenols metabolism and antioxidation of root tips(≈2 cm) were determined after 4, 24, 48, 100 and 196 h treatments. The results show that Al content of root tips increased with treating time, and Al content in cell wall was 73.10% of that in root tips. Pectin and hemicellulose 1(HC1) in cell wall had strong Al accumulation and adsorption ability. Meanwhile, phenylalanine ammonia-lyase(PAL) activity and contents of soluble phenol and cell wall-bound phenol increased, whereas activity of polyphenol oxidase(PPO) and covalently bound peroxidase(CPO) decreased under Al treatments. Addition of Al increased the activities of superoxide dismutase(POD), catalase(CAT) and peroxidase(POD), while decreased the contents of H2 O2 and malondialdehyde(MDA). Al supply also increased the contents of soluble sugar, soluble protein and free proline. The results suggest that the strong capability of Al adsorption and accumulation of pectin and HC1 in root tips of C. oleifera decreased the toxicity of Al. And 1 mmol·L-1 Al can increase the contents of phenols and decrease the activity of CPO, which is beneficial to enhance Al-stress tolerance and reduce cell wall lignification. In the meantime, increase of reactive oxygen species scavenging and osmotic regulation contributes to the stability of intracellular environment. Overall, the synergistic effect of various physiological response under suitable supply of Al improves the elongation of root tips of C. oleifera.