摘要
Guzmania monostachia (L.) Rusby ex Mez is an epiphytic, rosette-shaped bromeliad that displays variable degrees of crassulacean acid metabolism (CAM) along the leaf under water deficit. The aim of our study was to evaluate whether the production-scavenging system of reactive oxygen species (ROS) along the leaf length of G. monostachia plants is related to the foliar gradient of CAM when irrigation is withheld. Among the leaf portions, the apex was exposed to the highest photosynthetic flux density and presented the highest relative water content, CAM activity, hydrogen peroxide and lipid peroxidation after treatment. Hence, the most intense CAM at the leaf apex may not have prevented higher oxidative burden in that region during water deficiency. However, the photosynthetic efficiency in the apex seemed unaffected by irrigation withholding or light intensity. The leaf apex also had the highest carotenoid content and increased superoxide dismutase and ascorbate peroxidase activities under treatment. Hence, G. monostachia was able to maintain ROS under tolerable levels by increasing antioxidant capacity. Our results suggest the metabolic differences within the same leaf under water deficit may derive from the gradient of light incidence, which emphasises the physiological plasticity this bromeliad applies to adapt to the adverse conditions of the canopy.
摘要译文
Guzmania monostachia（L.）Guzmania monostachia（L.）Rusby ex Mez是一种附生的玫瑰状凤梨，在缺水的情况下沿叶片显示出不同程度的头孢烷酸代谢（CAM）。我们的研究目的是评估在不灌溉的情况下，田松植物叶片上活性氧的产生-清除系统是否与CAM的叶面梯度有关。在叶片部分中，根尖暴露于最高的光合通量密度，处理后呈现出最高的相对水含量，CAM活性，过氧化氢和脂质过氧化作用。因此，在缺水期间，叶尖处最强的CAM可能无法防止该区域较高的氧化负荷。然而，顶点的光合作用效率似乎不受灌溉抑制或光强度的影响。在处理过程中，叶尖的类胡萝卜素含量最高，超氧化物歧化酶和抗坏血酸过氧化物酶活性增加。因此，通过增加抗氧化剂的能力，单核孢菌能够将ROS维持在可容忍的水平之下。我们的结果表明，缺水情况下同一叶片内的代谢差异可能源于光入射的梯度，这强调了这种凤梨科植物可用于适应冠层不利条件的生理可塑性。
Maria E. Abreu [A];Victória Carvalho [B];Helenice Mercier [A] [C]. Antioxidant capacity along the leaf blade of the C3-CAM facultative bromeliad Guzmania monostachia under water deficit conditions[J]. Functional Plant Biology, 2018,45(6): 620-629