硅对铅胁迫下烟草铅含量、形态和亚细胞分布的影响

Effects of silicon on content,morphology and subcellular distribution of lead in tobacco under lead stress

为揭示硅对铅胁迫下烟草生长发育的影响及其机理,以K326为试验材料,Pb(NO_3)_2作为铅源,K_2SiO_3作为硅源,并用KNO_3和HNO_3消除因添加K_2SiO_3所带来营养液pH和K^+升高的影响,设置对照(CK)、100μmol·L^(-1)Pb^(2+)(Pb_(100))、300μmol·L^(-1)Pb^(2+)(Pb_(300))、100μmol·L^(-1)Pb^(2+)+1.0 mmol·L^(-1)SiO_2(Pb_(100)+Si)、300μmol·L^(-1)Pb^(2+)+1.0 mmol·L^(-1)SiO_2(Pb_(300)+Si)_5个处理的水培盆栽试验。结果表明,Pb_(100)和Pb_(300)处理的烟草株高分别较CK下降51.44%和69.92%,总生物量分别比对照下降51.43%和64.55%。硅可缓解铅胁迫对烟草的毒害作用,Pb_(100)+Si和Pb_(300)+Si处理的烟草株高分别比Pb_(100)和Pb_(300)处理提高69.23%和35.99%,总生物量分别比对照提高84.94%和76.75%,差异均达到极显著水平。硅可抑制铅由根系向地上部的迁移,降低铅胁迫下烟草茎杆、下部叶和上部叶的铅含量。硅可改变烟草铅的形态和亚细胞分布,表现为根系乙醇提取态铅和叶片Na Cl提取态铅的比例下降,而根系和叶片的盐酸提取态铅和残渣态铅的比例提高,与Pb_(100)和Pb_(300)处理相比较,Pb_(100)+Si和Pb_(300)+Si处理烟草根系细胞核中铅所占的比例分别降低25.29%和5.06%,叶片叶绿体中铅所占的比例分别降低29.22%和54.95%,线粒体中铅所占的比例分别降低38.09%和51.46%。

To study the effect of silicon on tobacco growth under lead stress and the underlying mechanism,hydroponic experiments were conducted on K326 with exogenous lead in the form of lead nitrate [Pb（NO3）2]and exogenous silicon in the form of potassium silicate（K2SiO3）. KNO3 and HNO3 were used to control the effects of increased pH and K＋of nutrient solutions caused by K2SiO3. In total,five treatments were set as following： control（CK）,100 μmol·L-1Pb2＋（Pb100）,300 μmol·L-1Pb2＋（Pb300 ）,100 μmol·L-1Pb2＋＋1.0 mmol·L-1SiO2（Pb100＋Si）and 300 μmol·L-1Pb2＋＋ 1.0 mmol·L-1SiO2（Pb300 ＋Si）. The results showed that comparing with the control,Pb100 and Pb300 treatments decreased the plant height and biomass of tobacco by 51.44%,69.92%and 51.43%,64.55%,respectively. Exogenous silicon could alleviate the harmfulness of lead stress on tobacco.Comparing with Pb100 and Pb300 treatments,the plant height and biomass of tobacco under Pb100＋Si and Pb300 ＋Si treatments increased by 69.23%,35.99% and 84.94%,76.75%,respectively; the differences were statistically significant. Silicon inhibited the migration of lead from root upwards and reduced the lead contents in stalk,lower leaves and upper leaves. Silicon decreased the proportion of ethanol-extractable lead in root and Na Cl-extractable lead in leaf,but increased the proportion of HCl-extractable and residual lead both in root and leaf. Comparing with Pb100 and Pb300 treatments,the lead proportion in nuclei of roots under Pb100＋Si and Pb300 ＋Si treatments decreased by 25.29% and 5.06%,respectively;the lead proportion in chloroplasts and mitochondria leaf decreased by 29.22%,54.95% and 38.09%,51.46%,respectively.