外源脱落酸对盐胁迫玉米激发能分配和渗透调节的影响

利用气体交换和叶绿素荧光技术,研究了外施脱落酸(ABA)对NaCl胁迫玉米的光合、激发能分配及渗透调节的影响。结果表明,NaCl胁迫条件下,外施ABA能降低玉米叶片的净光合而导致过剩激发能的增多,但是ABA提高了盐胁迫叶片的光化学猝灭(qP),增强了热耗散(NPQ)能力,减少了过剩激发能的积累,从而减轻盐胁迫造成的光抑制。此外,盐胁迫条件下,ABA还能诱导玉米叶片脯氨酸含量增加,提高玉米的渗透调节能力。ABA的这些作用有效增强了玉米的抗盐能力。

Effects of Exogenous ABA on Excitation Energy Distribution and Osmotic Adjustment of Maize Seedlings Under Salt Stress

Effects of exogenous ABA on excitation energy distribution and osmotic adjustment of maize seedlings under NaCl stress were studied by methods of gas exchange and chlorophyll fluorescence quench.In the presence of 200 mM NaCl,photosynthesis(Pn)and stomatal conductance(Gs)were decreased by addition of ABA.The obvious decrease of intercellular CO2(Ci)along with the decrease of Pn by addition of ABA indicated that the decrease of Pn was caused by the decrease of stomatal conductance,which led to the increase of excessive excitation energy.However,the addition of ABA increased photochemical quench(qP)and enhanced energy dissipation ability(NPQ),which decreased the accumulation of excessive excitation energy,then alleviated the photoinhibition caused by NaCl stress,this was manifested by the fact that the decrease of Fv/Fm in the presence of NaCl was mitigated by addition of ABA in the maize leaves.In addition,the plant water status of the maize leaves was improved by the application of ABA.The addition of ABA significantly increased water potential and decreased osmotic potential as well as inducing accumulation of proline,which enhanced osmotic adjustment of maize leaves under salinity stress to ensure leaves maintaining higher turgor pressure in osmotic stressed condition.These effects were the main reasons why exogenous ABA improved salt resistance in maize leaves.