Dynamic reorganization of microtubules and microfilaments in flax cells during the resistance response to flax rust infection

Abstract

Abstract. The cytoskeleton in plant cells is a dynamic structure that can rapidly respond to extracellular stimuli. Alteration of the organization of microtubules and actin microfilaments was examined in mesophyll cells of flax, Linum usitatissimum L., during attempted infection by the flax rust fungus, MeIampsora lini (Ehrenb.) Lev. Flax leaves that had been inoculated with either a compatible (yielding a susceptible reaction) or an incompatible (yielding a resistant reaction) strain of M. lini were embedded in butyl-methylmethacrylate resin; sections of this material were immunofluorescently labelled with anti-tubulin or anti-actin and examined using confocal laser scanning microscopy. In uninfected leaves, microtubules in the mesophyll cells formed a transverse array in the cell cortex. Microfilaments radiated through the cytoplasm from the nucleus. In an incompatible interaction, microtubules and microfilaments were extensively reorganized in mesophyll cells that were in contact with fungal infection hyphae or haustorial mother cells before penetration of the cell by the infection peg. After the initiation of haustorium development, microtubules disappeared from the infected cells, and growth of the haustoria ceased. In an incompatible interaction, hypersensitive cell death occurred in more than 70% of infected cells but occurred in less than 20% of cells in compatible interactions. After the infected cell had undergone hypersensitive cell death, the cytoskeleton in neighbouring cells became focused on the walls shared with the necrotic cell. In compatible interactions, reorganization of the cytoskeleton was either not observed at all or was observed much less frequently up to 48 h after inoculation.

Organisation and regulation of the cytoskeleton in plant programmed cell death

“…41 Later stages of HR are often accompanied by depolymerisation of F-actin. 42,43 Microtubule organisation is also affected by defence responses, but the response is variable. Disruption and apparent depolymerisation of the microtubule network at the penetration site has been observed in several systems (Figure 1n), 39,40,44 and it has been suggested that this might be an early sign of the HR.…”

“…Disruption and apparent depolymerisation of the microtubule network at the penetration site has been observed in several systems (Figure 1n), 39,40,44 and it has been suggested that this might be an early sign of the HR. 39,42 In other studies microtubules, like F-actin, concentrate at the infection site and undergo bundling, 42 but some studies 43 found no changes in the microtubule organisation upon pathogen attack. Treatment with cryptogein induces depolymerisation of microtubules 41,45 providing further support of the idea that microtubules are involved in HR.…”

Flow cytometric analysis of tracheary element differentiation in Zinnia elegans cells

“…This is well established from a number of Zinnia studies (see 31 and references therein), based on cortical microtubule rearrangement associated with cell isolation. In the hypersensitive response, links between microtubule and microfilament organization and cell death have been identified (32,33).…”

Changes in microtubule arrays in symbiotic orchid protocorms during fungal colonization and senescence

“…Interactions between fungi and plant species and using different methods of tissue prepcells also result in changes in the arrays of MTs in aration did not support this finding, plant cells. For example, various biotrophic fungal Mycorrhizal fungal associations with orchids are pathogens cause varying degrees of cortical MT of particular interest because of their essential role in depolymerization in plant cells during infection peg seed germination and protocorm development and or haustorium formation ; their similarity in many respects to biotrophic fungal Gross et al, 1993;Kobayashi, Kobayashi & infections. In most orchid species, fungal hyphae Hardham, 1994). Microtubules are absent from host invade the very reduced embryo and form hyphal cell cytoplasm contiguous to the haustorium coils called pelotons, which are separated from the branches, which are surrounded by host cell mem-host cytoplasm by an interfacial matrix and host brane.…”