聚乙二醇处理对‘717’杂交杨组培苗的影响

以‘717’杂交杨(‘INRA 717-1B4’杨)组培苗为试验材料,采用0、2.5%、5.0%、10.0%聚乙二醇(PEG)6000模拟干旱胁迫,研究PEG对‘717’杂交杨膜脂过氧化和抗氧化保护系统的影响。结果表明:(1)2.5%PEG处理促进了‘717’杂交杨的生长,而10.0%PEG显著抑制其生长。(2)PEG处理显著增加‘717’杂交杨幼苗体内H2O2和丙二醛(MDA)含量,其中10.0%PEG处理最显著。(3)3个PEG浓度处理都降低了‘717’杂交杨超氧歧化酶(SOD)的活性,浓度越大下降越大;而PEG处理后过氧化氢酶(CAT)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)活性4种酶活性都较对照显著提高,其中POD、APX活性都随着浓度增加和时间的延长而增强,而2.5%PEG处理10 d和5.0%PEG处理20 d后CAT活性最高,5.0%~10.0%PEG处理GR活性增加明显,但10.0%PEG处理后CAT与GR活性比5.0%处理的有所降低。(4)3个浓度PEG处理均能显著促进抗坏血酸(As A)和谷胱甘肽(GSH)含量的积累,As A含量在5.0%和10.0%PEG处理10 d时上升较显著,GSH含量在2.5%PEG处理10 d时含量显著高于对照,在10.0%PEG处理时GSH含量出现下降。结果表明,低浓度(2.5%)PEG处理刺激了‘717’杂交杨的生长状态,通过提高体内抗氧化酶活性和抗氧化剂的含量以维持其生长,而高浓度(10.0%)PEG处理时,细胞的ROS清除平衡被打破,细胞受到伤害。

Effect of polyethylene glycol treatment on hybrid poplar ( Populus tremula × P. alba '717-1B4' ) in vitro culture

The antioxidant ability of '717' hybrid poplar(Populus tremula L.×P. alba L. 'INRA 717-1B4')plantlets were studied under 0, 2.5%, 5.0%, 10.0% polyethylene glycol (PEG) 6000 treatments in vitro culture. The results showed that:(1)2.5% PEG promoted the growth of'717' hybrid poplar plantlets, however, 10.0%PEG inhibited its growth. (2)The content of hydrogen peroxide (H2O2) and MDA were found significant increase under PEG treatments, especially for the 10.0% concentration. (3)SOD went down as the concentration growing. Compared with the control, the activities of CAT, POD, APX and GR significantly increased after PEG treatment. The activities of POD and APX increased with the increase of concentration of PEG and time. At the 2.5% PEG treatment for 10 d and 5.0% PEG treatment for 20 d, the activity of CAT was the highest during the whole experiment. The activity of GR was significantly increased at 5.0%-10.0% PEG treatment, while at 10.0% PEG treatment, the activities of CAT and GR were decreased than those of 5. 0%. ( 4) All PEG treatments could significantly promote the accumulation of AsA and GSH. AsA content was significantly increased at 5.0% and 10.0% PEG treatment for 10 d and GSH content was significantly higher than that of the control at 2.5%PEG treatment for 10 d, then decreased at 10.0%. These results concluded that low concentration (2.5%) PEG promoted'717' hybrid poplar plantlets to increased antioxidant enzyme activities and antioxidant content to maintain its growth, while the intracellular ROS clearance balance was broken and the oxidative damage was exacerbated at high concentration (10.0%) PEG treatment.