Biomechanical responses of encysted zoospores of the oomycete Achlya bisexualis to hyperosmotic stress are consistent with an ability to turgor regulate

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dc.contributor.authorLacalendola N
dc.contributor.authorTayagui A
dc.contributor.authorTing M
dc.contributor.authorMalmstrom J
dc.contributor.authorWillmott GR
dc.contributor.authorGarrill A
dc.contributor.authorNock, Volker
dc.date.accessioned2022-05-10T03:12:39Z
dc.date.available2022-05-10T03:12:39Z
dc.date.issued2022en
dc.date.updated2022-02-22T01:48:51Z
dc.description.abstractZoospores are motile, asexual reproductive propagules that enable oomycete pathogens to locate and infect new host tissue. While motile, they have no cell wall and maintain tonicity with their external media using water expulsion vacuoles. Once they locate host tissue, they encyst and form a cell wall, enabling the generation of turgor pressure that will provide the driving force for germination and invasion of the host. It is not currently known how these spores respond to the osmotic stresses that might arise due to different environments on and around their hosts that have different osmotic strengths. We have made microaspiration (MA) measurements on >800 encysted zoospores and atomic force microscopy (AFM) measurements on 12 encysted zoospores to determine their mechanical properties and how these change after hyperosmotic stress. Two types of encysted zoospores (Type A and Type B) were produced from the oomycete Achlya bisexualis, that differed in their morphology and response. With a small hyperosmotic stress (using 0.1 and 0.2 M sorbitol to give media osmolality changes of 155.4 and 295.6 mOsmol/kg), Type A zoospores initially became stiffer, with an increase in the Young’s modulus (E) over 30 mins from 0.16 MPa to 0.25 and 0.22 MPa respectively. E then returned to its original value after 120 min. With a greater osmotic stress (using 0.3, 0.4 and 0.5 M sorbitol to give media osmolality changes of 438.2, 587.2 and 787.6 mOsmol/kg) the reverse occurred, with an initial decrease in E over 30 – 60 mins to values of 0.1, 0.08 and 0.09 MPa respectively, before recovery to the original value after 120 min. In 0.5 M sorbitol this recovery was only observed with AFM, but not with MA. Type B zoospores, which may be primary/secondary spores about to release secondary/tertiary spores, or else spores that were damaged during encystment, initially stiffened in response to the lower hyperosmotic stresses with a slight increase in E (from 0.077 to 0.1 MPa after 15 min (with both 0.1 and 0.2 M sorbitol) before recovering to the original value after 60 min. These spores showed no change in response to the higher osmotic stresses. The responses of the Type A spores are consistent with rapid changes in cell wall thickness and a turgor regulation mechanism. Turgor regulation is further supported by microscopic observations of the Type A spores showing protoplast retraction from the cell wall followed by deplasmolysis, coupled with measurements of spore volume. As far as we are aware this is the first demonstration of turgor regulation, not just in encysted zoospores, but in oomycetes in general.en
dc.identifier.citationLacalendola N, Tayagui A, Ting M, Malmstrom J, Nock V, Willmott GR, Garrill A (2022). Biomechanical responses of encysted zoospores of the oomycete Achlya bisexualis to hyperosmotic stress are consistent with an ability to turgor regulate. Fungal Genetics and Biology.en
dc.identifier.issn1087-1845
dc.identifier.urihttps://hdl.handle.net/10092/103657
dc.language.isoenen
dc.rightsAll rights reserved unless otherwise stateden
dc.rights.urihttp://hdl.handle.net/10092/17651en
dc.subjectoomyceteen
dc.subjectzoosporeen
dc.subjectYoung’s modulusen
dc.subjectturgor regulationen
dc.subjectmicroaspirationen
dc.subjectAFMen
dc.subject.anzsrc0604 Geneticsen
dc.subject.anzsrc0605 Microbiologyen
dc.subject.anzsrc0607 Plant Biologyen
dc.subject.anzsrcFields of Research::31 - Biological sciences::3107 - Microbiology::310705 - Mycologyen
dc.subject.anzsrcFields of Research::31 - Biological sciences::3107 - Microbiology::310702 - Infectious agentsen
dc.subject.anzsrcFields of Research::31 - Biological sciences::3108 - Plant biology::310803 - Plant cell and molecular biologyen
dc.subject.anzsrcFields of Research::31 - Biological sciences::3108 - Plant biology::310804 - Plant developmental and reproductive biologyen
dc.subject.anzsrcFields of Research::31 - Biological sciences::3101 - Biochemistry and cell biology::310105 - Cellular interactions (incl. adhesion, matrix, cell wall)en
dc.titleBiomechanical responses of encysted zoospores of the oomycete Achlya bisexualis to hyperosmotic stress are consistent with an ability to turgor regulateen
dc.typeJournal Articleen
uc.collegeFaculty of Engineering
uc.departmentElectrical and Computer Engineering
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