Pinkard E A, Mohammed C L
Cooperative Research Centre for Forestry, Private Bag 12, Hobart 7001, Australia.
New Phytol. 2006;170(1):119-27. doi: 10.1111/j.1469-8137.2006.01645.x.
Mycosphaerella leaf disease (MLD) is a major cause of foliage damage in Eucalyptus globulus plantations. Our study is the first to describe the physiological effects of MLD on E. globulus leaves. It involved measurements on both field and potted plants. Changes in photosynthetic parameters in response to MLD were quantified in a study using gas exchange techniques. There was a negative linear relationship between light-saturated photosynthesis (A(max)) and leaf-level damage from MLD. Reductions in A(max) were proportionally greater than might be expected from the reduction in green leaf area as a result of the disease, indicating that asymptomatic tissue also was affected by MLD. The reductions in A(max) were not related to increases in stomatal resistance, but were a result of reduced activity of ribulose bisphosphate carboxylase (Rubisco) and changes in the capacity for ribulose bisphosphate (RuBP) regeneration. Changes in mesophyll resistance to CO2 were also implicated. The effect of MLD was similar at different sites and irrespective of tree-level infection, suggesting a general leaf-level response of E. globulus to MLD.
球腔菌叶病（MLD）是蓝桉人工林中叶片受损的主要原因。我们的研究首次描述了MLD对蓝桉叶片的生理影响。该研究涉及对田间和盆栽植物的测量。在一项使用气体交换技术的研究中，对响应MLD的光合参数变化进行了量化。光饱和光合作用（A(max)）与MLD造成的叶片水平损伤之间存在负线性关系。A(max)的降低比例大于因该病导致绿叶面积减少所预期的比例，这表明无症状组织也受到了MLD的影响。A(max)的降低与气孔阻力增加无关，而是由于1,5-二磷酸核酮糖羧化酶（Rubisco）活性降低以及1,5-二磷酸核酮糖（RuBP）再生能力变化所致。叶肉对CO2的阻力变化也有影响。在不同地点，MLD的影响相似，且与树木水平的感染无关，这表明蓝桉对MLD存在普遍的叶片水平反应。
