盐适应过程中香根草内源游离态、结合态、束缚态多胺含量的变化

研究了不同浓度NaCl胁迫下，香根草（Vetiteria zizanioides）根、叶中的游离态、结合态、束缚态多胺（PAs）包括腐胺（Put），尸胺（Cad），亚精胺（Sod）和精胺（Spm）]含量的变化。在中度盐胁迫（100，200mmol L^-1NaCl）9天时，香根草基本能够正常生长，但在重度盐胁迫（300mmol L^-1NaCl）下，其生长受到严重抑制。在上述3个不同浓度的NaCl胁迫下，香根草根、叶中游离态Put，Cad，spd，Stma和总的游离态PAs含量明显下降，在高盐浓度下下降幅更大；结合态Put，Cad，Sod，Spm和总的结合态PAs含量显著上升，但在重度盐胁迫下升幅较小或与对照相当；束缚态Put，Cad和总的束缚态PAs含量均减少，而束缚态Spd和Spm含量在叶中是下降的，在根中则增加，且在中度盐胁迫下更明显。对根和叶片而言，除游离态（Spd＋Spm），Put比值在重度盐胁迫下较对照显著下降外，其它游离态、结合态、束缚态和总的（Spd＋Spm）／Put比值在不同盐胁迫下均上升，在中度盐胁迫下更明显。这表明，维持多胺总量的稳态和较高的（Spd＋Spm）／Put比值是香根草适应中度盐胁迫的一个重要机制。

Changes in Free,Conjugated and Bound Polyamine Content in Salt Adaptation of Vetiver Grass (Vetiveria zizanioides,Poaceae)

Polyamines(PAs)have been suggested to play roles in plant salt stress adaptation.In this study,alteration of free,conjugated and bound PAsputrescine(Put),cadaverine(Cad),spermidine(Spd) and spermine(Spm)] in roots and leaves of vetiver grass(Vetiveria zizanioides)seedlings in response to salt stress were investigated.Under moderate salt stresaes(100 and 200mmol L~(-1)NaCl)for 9 days,veliver grew at similar vigor compared with seedlings under normal Growth conditions.However,growth was severely arrested when plants were treated with severe salt stress(300mmol L~(-1) NaCl).Under three different concellmtions of NaCl stress mentioned above,the contents of free Put,Cad,Spd,Spm and total free PA substantially decreased in roots and leaves,and more severe loss of free PAs was observed under higher NaCl concentration.Conjugated Put,Cad,Spd,Spin,and total conjugated PAs remarkably increased,and the extent of the in-crease after 300mmol L~(-1) NaCl treatment was smaller than those after 100 or 200mmol L~(-1) NaCl treatments.Bound Put,Cad and total bound PAs decreased in both roots and leaves under salt stress,moreover,bound Spd and Spm decreased in leaves while increased in roots in response to salt treatments,and the more obvious rise was displayed under moderate salt stresses.With the excoption of the significant decreases of free(Spd+Spm)/Put ratio in roots and leaves after 300mmol L~(-1) NaCl treatment,other ratios of free,conjugated,bound and the total(Spd+Spm)/Put increased in roots and leaves of veilver grass seedlings after different salt treatments,and especially under moderate salt stress.These results indicated that maintaining homeostasis of total PAs content and high(Spd+Spm)/Put ratios could be an adaptation mechanism in vetiver grass to moderate saline environment.