茶树根系XTHs和伸展蛋白对不同浓度铝的响应

Responses of Expansins and XTHs to different aluminum concentrationa in roots of tea plant[Camellia sinensis(L.) O. Kuntze]

为探索铝对茶树根系生长的影响,以一年生安吉白茶扦插苗为研究材料,比较不同铝浓度处理28 d后茶树根系生长的表型差异、生长参数,以及细胞壁相关蛋白XTHs[木葡聚糖内转糖苷酶(XET)/水解酶(XEH)]和伸展蛋白(Expansins)的响应。结果表明,与无铝对照相比,加铝处理的茶树根系在表型、生长参数上均表现出了促进生长的现象,尤其是0.4、1.0 mmol·L^(-1)的铝处理下与对照差异显著(P<0.05),根系总长分别增加了206%和209%、根尖数分别增加了175%和166%、根系表面积分别增加了227%和286%、根系体积分别增加了246%和385%。相应地,茶树根系中Cs EXPB14、Cs EXLA8基因表达量在0.4 mmol·L^(-1)铝处理下显著(P<0.05)高于对照与4.0 mmol·L^(-1)铝处理组。Expansins活性也在0.4 mmol·L^(-1)铝浓度下最高,较不加铝处理提高了84.3%。Cs XTH14基因表达量在0.4、1.0 mmol·L^(-1)铝浓度下较对照显著(P<0.05)上调,XET酶活性亦表现出随铝浓度升高而增加的趋势,直至4.0 mmol·L^(-1)的铝浓度下才受到显著抑制。XTHs和Expansins基因表达、XET和Expansins活性与根系生长呈正相关关系,表明一定浓度的铝(≤1mmol·L^(-1))处理,可以通过诱导XTHs和Expansins基因表达上调,提高XET和Expansins活性,促进茶树根系的生长。

In order to investigate the effect of aluminium（ Al） on root growth of tea plants [Camellia sinensis（ L.）O. Kuntze],Anjibaicha tea plant was selected as study material with different Al concentrations for 28 d. Then,the phenotypic differences and parameters of roots,activities of the Expansins and xyloglucan endotransglucosylase（ XET）,and the gene expression level of Expansins and XTHs,which were related with root growth and key proteins of cell wall were assayed. The results showed that the Al could promote the root growth of tea plant on phenotypic and parameters. The treatment with 0. 4,1. 0 mmol·L^（-1） Al showed significant（ P〈0. 05） difference with control,as theroot total length was increased by 206% and 209%,respectively,the number of root tips was increased by 175%and 166%,respectively,the root surface area was increased by 227% and 286%,respectively,and the root volume was increased by 246% and 385%,respectively. Correspondingly,the gene expression level of Cs EXPB14 and the expansins-like gene Cs EXLA8 in the roots treated with 0. 4 mol·L^（-1） Al were significantly（ P〈0. 05） higher than those without Al or with 4. 0 mmol·L^（-1） Al. The expansins activity in the roots with 0. 4 mmol·L^（-1） Al was higher than other treatments and was increased by 84. 3% as compared to the control. The expression level of Cs XTH14 in the roots with 0. 4,1. 0 mmol·L^（-1） Al were significantly（ P〈0. 05） higher than the other treatments,and XET activity was increased with the elevated Al concentration,and was significantly（ P〈0. 05） inhibited until the Al concentration reached up to 4. 0 mmol·L^（-1）. The gene expression level of Expansins and XTHs,the activities of XET and Expansins showed a positive correlation with root growth of tea plant,which indicated that Al（ ≤1 mmol·L^（-1）） could increase XET and Expansins activity by promoting the gene expression of Expansins and XTHs,hence,promote root growth of tea plants.