水稻幼苗根对羧基化多壁碳纳米管复合镉胁迫的生长生理响应

为了探究羧基化多壁碳纳米管(MWCNTs-COOH)复合镉(Cd)胁迫对植物生长生理的影响,采用液体培养方法,以水稻(Oryza sativa L.)为受试作物,测定了0~12.0 mg·L^-1MWCNTs-COOH、10μmol·L-1Cd单一和复合处理水稻幼苗21天后根生长、氧化损伤、抗氧化酶活性及根中Cd含量的变化。结果表明:(1)MWCNTs-COOH单一处理,根长、根鲜重均低于对照,并表现出先升高后降低的趋势,当其浓度达到12.0 mg·L^-1时,较对照分别下降了9.3%和15.2%,且低于10μmol·L^-1Cd单一处理;而复合处理组水稻幼苗根长、根鲜重、干重皆低于对应的单一处理;(2)MWCNTs-COOH单一胁迫下,水稻根的超氧自由基(O2-·)明显积累,并伴随着超氧化物歧化酶(SOD)及过氧化物酶(POD)活性升高,3.0和6.0mg·L^-1MWCNTs-COOH处理下,SOD、POD活性最高;(3)MWCNTs-COOH复合Cd胁迫下,水稻根的SOD、POD活性大均低于单一处理组,而丙二醛(MDA)及羰基化蛋白含量均显著高于单一处理;(4)MWCNTs-COOH复合Cd后,水稻幼苗根尖细胞死亡加剧,其中,10μmol·L-1Cd与12.0 mg·L^-1MWCNTs-COOH复合处理的根尖根冠区细胞伊文斯蓝染色最深;(5)1.5~6.0 mg·L^-1MWCNTs-COOH复合Cd处理水稻幼苗后,其根中Cd含量呈上升趋势,且在6.0 mg·L^-1浓度处理时达到最大值303.30μg·g-1;高浓度MWCNTs-COOH及其与Cd的复合均对水稻根产生毒性效应。

Responses of growth and physiology of rice (Oryza sativa L.) seedling roots to MWCNTs-COOH combined with Cd stress.

To investigate the effects of carboxylated multi-walled carbon nanotubes(MWCNTsCOOH) combined with cadmium(Cd) stress on plant growth and physiology,we measured the changes of root growth,oxidative damage,activity of antioxidant enzymes,and contents of cadmium in roots of rice(Oryza sativa L.) seedlings treated with MWCNTs-COOH(0-12. 0 mg·L^-1) and Cd(10 μmol·L-1) for three weeks. The results showed that:(1) Root length and fresh weight in MWCNTs-COOH treatment were lower than those of the control,and they increased first and then decreased over time. When the concentration of MWCNTs-COOH reached12.0 mg·L^-1,root length and fresh weight were lower than those of the control,with a reduction of 9.3% and 15.2%,respectively.(2) Root length,fresh weight and dry weight of rice seedlings treated with the combination of MWCNTs-COOH and Cd were lower than those of the MWCNTsCOOH treatment alone. Under MWCNTs-COOH stress,superoxide radicals(O2-·) accumulated significantly,and superoxide dismutase(SOD) and peroxidase(POD) activities of rice increased. SOD and POD activities were the highest under 3.0 and 6.0 mg·L^-1 MWCNTs-COOH treatments;(3) SOD and POD activities of rice roots under MWCNTs-COOH combined Cd stress were lower,while malondialdehyde(MDA) and carbonylation protein contents were significantly higher than those under Cd stress alone.(4) When rice was treated with combination of MWCNTs-COOH and Cd,the death of root tip cells accelerated. Most of the root cap cells treated with10 μmol·L^-1 Cd+12.0 mg·L^-1 MWCNTs-COOH were stained with Evans Blue.(5) After treated with 1.5-6.0 mg·L^-1 MWCNTs-COOH and Cd,the cadmium contents in the roots of rice seedlings showed an increasing trend,and reached a maximum of 303.30 μg·g^-1 at the concentration of 6.0 mg·L^-1. Our results indicated that high concentrations of MWCNTs-COOH and its combination with Cd are toxic to rice roots.