INFIVE (CONICET-Universidad Nacional de La Plata), Diag 113 n° 495, CC 327, 1900 La Plata, Argentina.
Facultad de Ciencias Forestales, Universidad Nacional de Misiones, Bertoni 124, 3380 Eldorado, Misiones, Argentina.
Tree Physiol. 2018 Jun 1;38(6):925-935. doi: 10.1093/treephys/tpx174.
Rust produced by Melampsora sp. is considered one of the most relevant diseases in poplar plantations. Growth reduction in poplar plantations takes place because rust, like other pathogens, alters leaf physiology. There is not a complete evaluation of several of the physiological traits that can be affected by rust at leaf level. Therefore, the aim of this work was to evaluate, in an integrative way and in the same pathosystem, which physiological processes are affected when Populus deltoides Bartr. ex Marsh. leaves are infected by rust (Melampsora medusae Thümen). Leaves of two clones with different susceptibility to rust were analyzed. Field and pot experiments were performed, and several physiological traits were measured in healthy and infected leaves. We conclude that rust affects leaf mesophyll integrity, and so water movement in the leaf in liquid phase is affected. As a consequence, gas exchange is reduced, affecting both carbon fixation and transpiration. However, there is an increase in respiration rate, probably due to plant and fungal respiration. The increase in respiration rate is important in the reduction of net photosynthetic rate, but also some damage in the photosynthetic apparatus limits leaf capacity to fix carbon. The decrease in chlorophyll content would start later and seems not to explain the reduction in net photosynthetic rate. Both clones, although they have different susceptibility to rust, are affected in the same physiological mechanisms.
由杨栅锈菌引起的锈病被认为是杨树人工林最相关的病害之一。由于锈病与其他病原体一样会改变叶片的生理学特性，因此会导致杨树人工林的生长减少。目前还没有对叶片水平上可能受到锈病影响的几个生理特性进行全面评估。因此，本工作的目的是在同一病理系统中以综合的方式评估当杨树叶受到锈病（杨栅锈菌）感染时哪些生理过程会受到影响。分析了对锈病具有不同敏感性的两个无性系的叶片。进行了田间和盆栽实验，并测量了健康和感染叶片的几个生理特性。我们得出结论，锈病会影响叶片叶肉的完整性，从而影响叶片液相中的水分运动。因此，气体交换减少，影响碳固定和蒸腾作用。然而，呼吸速率增加，可能是由于植物和真菌的呼吸作用。呼吸速率的增加对净光合速率的降低很重要，但光合作用器的一些损伤也限制了叶片固定碳的能力。叶绿素含量的下降会较晚开始，而且似乎不能解释净光合速率的降低。尽管这两个无性系对锈病的敏感性不同，但它们受到相同的生理机制的影响。
