大麦幼苗叶片脯氨酸代谢及其与耐盐性的关系  

Proline metabolism in the leaves of barley seedlings and its relation to salt tolerance

作　　者：赵福庚[1] 刘友良[1] 章文华[1] 

机构地区：[1]南京农业大学农业部作物生长调控重点开放实验室,江苏南京210095

出　　处：《南京农业大学学报》2002年第2期6-10,共5页Journal of Nanjing Agricultural University

基　　金：国家自然科学基金项目 (3 0 0 70 45 5 )

摘　　要：在 0～ 30 0mmol·L-1NaCl浓度范围内 ,大麦叶片内催化脯氨酸 (Pro)合成的关键酶吡咯啉 5 羧酸合成酶 (P5CS)、精氨酸酶、鸟氨酸转氨酶 (OAT)和谷氨酸脱氢酶 (GDH)的活性均明显提高 ,脯氨酸脱氢酶 (ProDH)活性略有下降 ,与之相对应 ,叶片内Pro含量上升 4～ 11倍。 2 0 0mmol·L-1NaCl以下浓度处理 ,Pro合成主要是通过谷氨酸 (Glu)途径(关键酶为P5CS) ,2 0 0mmol·L-1以上NaCl胁迫下鸟氨酸 (Orn)途径 (关键酶为OAT)受激。ΔGR/ΔNaCl (每提高单位NaCl浓度时植株生长速率的下降值 )可以代表植物的耐盐性 ,植物耐盐性越强该比值越小。统计表明 ,大麦ΔGR/ΔNaCl与叶片ΔPro/(Arg +Glu)·Δ1/NaCl (每提高单位NaCl浓度时叶片内Pro/(Arg +Glu)的上升值 )呈极显著负相关关系 ,与一定浓度NaCl处理下叶片K+ /Na+ 呈极显著负相关关系 ,说明盐处理后Arg和Glu向Pro的转化有利于大麦耐盐性的提高。在 10 0mmol·L-1NaCl处理时 ,ΔGR/ΔNaCl值与Pro对植株渗透势的贡献呈显著负相关 ,说明盐胁迫下Pro积累具有渗透保护剂的功能。When subjected to 0?300 mmol·L -1 NaCl stress,P5CS,a key enzyme invovled in proline(Pro)synthesis arginase,OAT and GDH activities in barley (Hordeum vulgare L.)seedling leaves,were all increased remarkably,while ProDH activity decreased slightly,leading a 4～11?fold increase in leaf Pro content.When NaCl concentration was below 200 mmol·L -1 ,Pro synthesis was mainly through Glu pathway(P5CS was a key enzyme),while Orn pathway was predominant when NaCl concentration was beyond 200 mmol·L -1 NaCl.ΔGR/ΔNaCl means a decreased value in plant growth rate per unit of increased NaCl concentration,which can present plant salt tolerance:the more strong salt tolerance of plant was,the lower the ratio of ΔGR/ΔNaCl was.Statistic analysis showed that a very significant negative correlation existed between ΔGR/ΔNaCl and ΔPro/(Arg+Glu)·Δ1/NaCl(the increased value in ΔPro/(Arg+Glu)per unit of increased NaCl concentration)in leaves,such correlation also existed between ΔGR/ΔNaCl and the leaf K +/Na + under a certain concentration of NaCl.These results indicated that the conversion of Arg and Glu to Pro was beneficial to improve salt tolerance of barley seedlings.With the treatment of 100 mmol·L -1 NaCl,ΔGR/ΔNaCl was significant negatively correlated with the contribution of Pro to plant osmotic potential,suggesting Pro accumulation had the function of osmoprotectant.

关 键 词：大麦 幼苗 叶片 脯氨酸 代谢 耐盐性 吡咯啉-5-羧酸合成酶 乌氨酸转氨酶 

分 类 号：S512.3[农业科学—作物学] Q945[生物学—植物学]