Manganese stress on morphological structures of leaf and ultrastructures of chloroplast of a manganese hyperaccumulator,Phytolacca americana
Manganese stress on morphological structures of leaf and ultrastructures of chloroplast of a manganese hyperaccumulator,Phytolacca americana
复制标题
作者：
W. Jun
采用不同浓度锰(Mn)水培法，研究了锰胁迫下商陆的毒性症状、叶片形态结构和叶绿体超微结构的变化。结果表明，该锰超富集植物对锰具有显着的耐受性。在营养培养条件下，锰浓度为1000 μmol/L时，美洲商陆能生长良好。随着培养物中锰浓度的增加，商陆的生长状况良好。溶液中,美洲对虾叶片形态结构和叶绿体超微结构发生了一定的变化,当Mn浓度达到5000μmol/L时,叶片出现失绿和药害症状,叶面出现黄棕色斑点;当Mn浓度超过12000μmol/L时,暴露30 d,叶片表面出现紫色斑点,药害率为87.33%。当Mn浓度达到12000μmol/L以上时，叶肉和表皮细胞发生扭曲，随着Mn浓度的进一步增加，叶绿体萎缩，外膜破裂，类囊体肿胀，严重凹陷，基质片层扭曲，基粒紊乱或模糊成絮状，淀粉粒变成尽管在重锰胁迫下美洲对虾的叶片形态结构和叶绿体超微结构发生了显着变化，但该物种仍能存活和生长，这些都表明美洲对虾对锰具有非凡的耐受性。
The toxicity symptoms,changes of leaf morphological structures and chloroplast ultrastructures of Phytolacca americana under manganese stress were investigated using hydroponic culture with different concentrations of manganese(Mn).The results indicated that this Mn hyperaccumualator species has a remarkable tolerance to Mn.Under nutrient culture conditions,P.americana could grow quite well with Mn supplied at a concentration of 1000 μmol/L.With the increase of Mn concentration in the culture solution,the leaf morphological structures and chloroplast ultrastructures of P.americana had some changes.At the Mn concentration reached 5000 μmol/L,the leaves showed chlorosis and injury symptoms with yellow-brown spots on the leaf surface.When Mn concentration exceeded 12000 μmol/L,the leaves showed purple spots on the surface during the 30-day Mn exposure,with an injury rate of 87.33%.Significant changes in leaf structure were noted,with swollen palisade cells which arranged loosely.When Mn concentration reached above 12000 μmol /L,the mesophyll and epidermal cells were distorted.With further increase of Mn concentration,the chloroplasts were shrunk with outer membrane disrupted,and the thylakoids swollen and became heavily hollowed.The stroma lamellae was distorted and grana disordered or blurred as floc,starch grains became smaller and less,and osmiophilic granules increased.Although the leaf morphological structures and chloroplast ultrastructures of P.americana had significant changes under heavy Mn stress,this species could still survive and grow.All these suggested that P.americana had an extraordinary tolerance to Mn.