硅对铬胁迫下小麦幼苗超微结构和铬吸收积累的影响

为探讨水培条件下外源硅对小麦铬毒害的缓解效应,以小麦品种京冬8号为材料,设置2种不同的铬浓度(0.4和0.8 mmol· L-1)和3种不同的硅浓度(0.5、1.0和1.5 mmol· L-1)梯度,研究了铬胁迫下硅对小麦幼苗铬吸收积累和超微结构的影响.结果表明,0.4 mmol·L-1铬胁迫下,硅浓度达0.5mmol·L-1时可以有效抑制小麦根系对铬的吸收积累,显著降低根系铬浓度和富集系数;0.8 mmol·L-1铬胁迫下,硅浓度达到1.0 mmol·L-1时可以有效抑制小麦根系对铬的吸收积累,显著降低根系铬浓度和富集系数.硅处理有使小麦叶鞘和叶片的铬浓度、富集系数和转移系数整体升高的趋势.硅可以减轻铬胁迫对小麦细胞超微结构的伤害,维持细胞形状的规则和结构的完整性,维护膜系统结构的正常和完整,恢复叶绿体的形状和类囊体结构的整齐规则,使线粒体结构恢复完整及内嵴结构清晰,恢复细胞核的完整性,且在试验范围内随硅浓度增大,缓解程度逐渐增大.

Effect of Silicon on Ultrastructure,Chromium Absorption and Accumulation of Wheat Seedlings under Chromium Stress

The current study was to explore the mitigatory effects of silicon on chromium toxicity at hydroponic condition. The ultrastructure,chromium absorption and accumulation of wheat seedlings were investigated with two concentration levels of chromium (0.4 and 0.8 mmol·L^-1)and three concentration levels of silicon (0.5,1.0 and 1.5 mmol·L^-1). The results indicated that 0.5 mmol·L^-1 silicon-treatment could effectively suppress chromium accumulation and significantly reduce the concentration of chromium and bioconcentration factor in wheat roots when wheat seedlings were treated with 0.4 mmol·L^-1 chromium solution. Similarly,1.0 mmol·L^-1 silicon-treatment could effectively suppress chromium accumulation and reduce the concentration of chromiumin wheat roots when wheat seedlings were handled with 0.8 mmol·L^-1 chromium solution. Silicon-treatment tended to increase the concentration of chromium,bioconcentration factor and transfer coefficient in both leaf sheaths and leaves. The structure of cell,membrane system,chloroplast,thylakoid,mitochondria and mitochondrial crista were recovered with the addition of silicon under chromium stress. The integrity of cell nucleus was also recovered. The damage of chromium stress on ultrastructure of wheat seedlings were mitigated with the addition of silicon,and the mitigation was enhanced as the increase of silicon concentration.