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

Abstract

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.

Rust Infection of Black Poplar Trees Reduces Photosynthesis but Does Not Affect Isoprene Biosynthesis or Emission

“…Consistent with this, the levels of the chlorophylls and most carotenoids, the main non-volatile products of the MEP pathway, did not change after rust infection (Table 3 ). Constant levels of the chlorophylls in leaves after rust infection were also recently reported in another poplar species ( Gortari et al, 2018 ). However, the levels of DMADP and IDP (quantified together in our LC-MS analysis) increased after infection (Figure 4E ).…”

“…Despite the central importance of photosynthesis in supplying plants with carbon, energy, and reducing equivalents, we observed an immediate and sustained decrease in photosynthetic activity in rust-infected black poplar leaves of nearly 50%, from 4 hpi to 10 dpi (Figure 1 ). Infection of poplar with Melampsora leaf rust was earlier reported to be associated with a marked reduction in photosynthesis ( Zhang et al, 2010 , 2016 ; McKown et al, 2014 ; Jiang et al, 2016 ; Gortari et al, 2018 ), but the detailed temporal dynamics of this reduction had not been studied. In willow, a similar pattern of decreased net photosynthetic rate was observed after rust infection, but stomatal conductance changed only at late time points ( Toome et al, 2010 ).…”

Addressing Gender Inequities in Forest Science and Research

“…Her research focuses on tree ecophysiology of exotic and native timber species. Her notable works include evaluating nutrient-water interactions [67,68] and plant responses to pathogens [69,70]. Her recent works have included evaluating strategies to restore degraded rain forests with native trees in the Atlantic Forest in Argentina [71].…”

Non‐linear reduction of photosynthetic ability in oak trees infected with Tubakia koreana causing Quercus leaf blight

“…It is well accepted through previous studies on other pathogens that leaf spotting, blotching and necrosis lead to changes in photosynthetic ability, growth and respiration, as well as carbon and water transport systems in leaves (Oliva et al., 2014). For example, foliar pathogens can cause a serious reduction in the photosynthetic ability of host plants, resulting from direct effects on photosynthetic processes, indirect effects of a reduction in stomatal conductance or both—as exemplified by a variety of foliar pathogens which influence the induction of stomatal closure (Gortari et al., 2018; Grimmer et al., 2012; Hajji et al., 2009; Jeong et al., 2019; Mignucci & Boyer, 1979; Niederleitner & Knoppik, 1997; Pinkard & Mohammed, 2006). It is known that foliar pathogens can negatively affect the activity of ribulose‐1,5‐bisphosphate carboxylase‐oxygenase or other enzymes of the Calvin cycle leading to the reduction in carboxylation efficiency (Mayr et al., 2001; Pennypacker et al., 1990; Pinkard & Mohammed, 2006).…”