小麦幼苗叶片抗氰呼吸对轻度水分胁迫的响应

摘要

小麦幼苗经-0.5 MPa聚乙二醇(PEG-6000)溶液暗中渗透胁迫0、6、12、18、24、30、36、42、48 h，叶片的总呼吸速率(Vt)呈现先上升后降低的趋势，交替途径呼吸也表现出相同的变化模式。水分胁迫初期(0～12 h)，交替途径容量(Valt)、实际运行活性(ρValt)及运行系数(ρ值)均上升，此后(18～48 h)逐渐下降。水分胁迫也影响了呼吸电子流在2条呼吸途径中的分配比例。胁迫初期的0～12 h内，流经交替途径的电子流增多，而流向细胞色素主路的电子流减少；但随着胁迫时间的延长，交替途径的贡献降低，而细胞色素主路的贡献增加。说明小麦叶片的抗氰呼吸在水分胁迫初期被诱导增加，而随着胁迫进程的延长又表现为下降。%When wheat seedlings were root-stressed osmotically in -0.5 MPa polyethylene glycol (PEG) solutions in dark for 0,6,12,18,24,30,36,42,48 h,leaf total respiratory rate (Vt) increased at first within the 0～12 h of stress but decreased afterwards.So were the changes of alternative pathway capacity (Valt),its actual operation activity (ρValt) and engagement (ρ value).The Valt/Vt ratio and the contribution of alternative pathway to total respiration (ρValt/Vt) also increased at the early stage of water stress.In addition,water stress led to a reallocation of respiratory electron flow between two respiratory pathways.During the first 12 h of water stress,electron flux flowed through the alternative pathway increased,but afterwards it diverted to cytchrome pathway and led to an increase of the contribution of cytochrome pathway.These results suggest that the cyanide-resistant respiration of wheat leaves was induced at the onset of water stress but suppressed under further stress conditions.