Plant–pathogen interactions: leaf physiology alterations in poplars infected with rust (Melampsora medusae)

GORTARI, FERMÍN; GUIAMET, JUAN JOSÉ; GRACIANO, CORINA

TREE PHYSIOLOGY

Oxford University Press

Año: 2018 vol. 38 p. 925 - 935

0829-318X

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 severalof the physiological traits that can be affected by rust at leaf level. Therefore, the aim of this work was to evaluate, in an integrativeway and in the same pathosystem, which physiological processes are affected when Populus deltoides Bartr. ex Marsh. leaves areinfected by rust (Melampsora medusae Thümen). Leaves of two clones with different susceptibility to rust were analyzed. Fieldand pot experiments were performed, and several physiological traits were measured in healthy and infected leaves. We concludethat rust affects leaf mesophyll integrity, and so water movement in the leaf in liquid phase is affected. As a consequence, gasexchange is reduced, affecting both carbon fixation and transpiration. However, there is an increase in respiration rate, probablydue to plant and fungal respiration. The increase in respiration rate is important in the reduction of net photosynthetic rate, butalso some damage in the photosynthetic apparatus limits leaf capacity to fix carbon. The decrease in chlorophyll content wouldstart 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.