NaCl胁迫增强杂交酸模(Rumex K-1)幼苗叶片光系统Ⅱ的耐热性

NaCl胁迫对杂交酸模幼苗光系统Ⅱ(PS Ⅱ)的最大光化学效率没有影响,但是增强了PS Ⅱ的耐热性.热胁迫条件下,与未经盐胁迫处理的叶片相比,经NaCl 200 mmol/L处理的杂交酸模幼苗叶片,其PS Ⅱ最大光化学效率下降较小,反映OEC受伤程度的指标Fk/Fj上升较小.此外,光化学猝灭系数(qP)、PS Ⅱ反应中心光能捕获效率(Fv1/Fm1)、PS Ⅱ光化学转换效率(ΦPS Ⅱ)的下降以及QB-非还原性反应PS Ⅱ反应中心的相对含量上升程度也较小.探讨了盐胁迫增强杂交酸模幼苗叶片PS Ⅱ耐热性的可能机理.

NaCl Stress Increases the Heat Tolerance of PSII in Leaves of Rumex K-1 Seedlings

By measuring chlorophyll fluorescence, the effects of NaCl treatment on the maximal efficiency and heat tolerance of PSII were examined in leaves of Rumex seedlings. NaCl 200 mmol/L treatment had no effect on the maximal efficiency of PSII, but increased the heat tolerance of PSII in Rumex leaves. Compared with control leaves, the heat stress-induced decrease in F(v)/F(m) and the increase in F(k)/F(j) ratio were less in NaCl-treated leaves. In addition, the heat stress-induced decrease in photochemical quenching (q(P)), the efficiency of excitation energy capture by open PSII reaction center (F(v)' /F(m)') and the quantum yield of electron transport (PhiPSII) were less in NaCl-treated leaves. Moreover, the increase in the Q(B)-non-reducing PSII reaction center content was less in NaCl-treated leaves than in control leaves. Discussion was made on the possible mechanisms of the increase in the heat tolerance of PSII in NaCl-treated leaves.