Keeping Control: The Role of Senescence and Development in Plant Pathogenesis and Defense

Abstract

Many plant pathogens show interactions with host development. Pathogens may modify plant development according to their nutritional demands. Conversely, plant development influences pathogen growth. Biotrophic pathogens often delay senescence to keep host cells alive, and resistance is achieved by senescence-like processes in the host. Necrotrophic pathogens promote senescence in the host, and preventing early senescence is a resistance strategy of plants. For hemibiotrophic pathogens both patterns may apply. Most signaling pathways are involved in both developmental and defense reactions. Increasing knowledge about the molecular components allows to distinguish signaling branches, cross-talk and regulatory nodes that may influence the outcome of an infection. In this review, recent reports on major molecular players and their role in senescence and in pathogen response are reviewed. Examples of pathosystems with strong developmental implications illustrate the molecular basis of selected control strategies. A study of gene expression in the interaction between the hemibiotrophic vascular pathogen Verticillium longisporum and its cruciferous hosts shows processes that are fine-tuned to counteract early senescence and to achieve resistance. The complexity of the processes involved reflects the complex genetic control of quantitative disease resistance, and understanding the relationship between disease, development and resistance will support resistance breeding.

Overexpression of phytoglobin in barley alters both compatible and incompatible interactions with the mildew pathogen Blumeria graminis

“…Plants need to tightly control the level of ROS to prevent oxidative damage and to control the redox status of the cell (Singh et al ., ). The plant response to ROS depends on when, where and how ROS formation is induced, and different systems are effective for different types of host–pathogen interactions (Häffner et al ., ). ROS bursts are characteristic for effector‐triggered HR (Scheler et al ., ), which is the main defence mechanism against the avirulent isolate (Race 1) as indicated here by the high frequency of autofluorescent host cells.…”

“…Interestingly, the delayed senescence of GPHb1 plants seemed to promote pathogen growth as evaluated by a significantly higher level of fungal DNA compared to the GP plants at 14 dai. This suggests that senescence in compatible biotrophic plant–fungal interactions may be a means by plants to limit spread of disease within a plant community by limiting fungal growth on the individual plant (Häffner et al ., ).…”

Systemic changes in photosynthesis and reactive oxygen species homeostasis in shoots of Arabidopsis thaliana infected with the beet cyst nematode Heterodera schachtii

“…Thus, the levels of and H 2 O 2 reflect the SOD and CAT activities. The intense accumulation of in leaves of uninfected plants at 15 dpi seems to be linked to developmental events, especially with leaf senescence, during which ROS concentrations are enhanced (Häffner et al ., ).…”

Natural allelic variation of GVS1 confers diversity in the regulation of leaf senescence in Arabidopsis

“…potassium), play important functions during senescence by maintaining transpiration and photosynthetic activity, change in redox states and electron transport (Table S1; Kobayashi et al ., ; Tanoi & Kobayashi, ). Diverse stress responses, such as the response to pathogens and anthocyanin accumulation, also correlated with leaf senescence in accessions, which is consistent with previous work indicating an overlap between leaf senescence and defense response programs (Haffner et al ., ). For example, many defense response genes are induced through leaf aging, and many senescence mutants exhibit altered defense responses (Buchanan‐Wollaston et al ., ; Breeze et al ., ; Lee et al ., ; Woo et al ., ).…”