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Tracking host infection and reproduction of Peronospora salviae‐officinalis using an improved method for confocal laser scanning microscopy
Author(s) -
Hoffmeister Mascha,
Maier Wolfgang,
Thines Marco,
Becker Yvonne
Publication year - 2020
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1111/ppa.13173
Subject(s) - downy mildew , biology , oomycete , botany , basilicum , sepal , ocimum , pathogen , microbiology and biotechnology , pollen , stamen
Peronospora salviae‐officinalis , the causal agent of downy mildew on common sage, is an obligate biotrophic pathogen. It grows in the intercellular spaces of the leaf tissue of sage and forms intracellular haustoria to interface with host cells. Although P . salviae‐officinalis was described as a species of its own 10 years ago, the infection process remains obscure. To address this, a histological study of various infection events, from the adhesion of conidia on the leaf surface to de novo sporulation is presented here. As histological studies of oomycetes are challenging due to the lack of chitin in their cell wall, we also present an improved method for staining downy mildews for confocal laser scanning microscopy as well as evaluating the potential of autofluorescence of fixed nonstained samples. For staining, a 1:1 mixture of aniline blue and trypan blue was found most suitable and was used for staining of oomycete and plant structures, allowing discrimination between them as well as the visualization of plant immune responses. The method was also used to examine samples of Peronospora lamii on Lamium purpureum and Peronospora belbahrii on Ocimum basilicum , demonstrating the potential of the presented histological method for studying the infection processes of downy mildews in general.