Tracking host infection and reproduction of Peronospora salviae‐officinalis using an improved method for confocal laser scanning microscopy

Abstract

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. K E Y W O R D Saniline blue, confocal laser scanning microscopy, Peronospora belbahrii, Peronospora lamii, Peronospora salviae-officinalis, trypan blueThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Efficiency of composted vinasse in the production of basil (Ocimum basilicum L.) under greenhouse conditions

“…In addition to the use of basil in meals as a spice, its essential oil is also used in the food industry and perfumery (Baytop 1984;Telci et al 2006) and as a medicinal plant in Anatolia. Today, it was determined that the basil can also be used as a teeth whitening agent (Yeşil et al 2020); a pesticide (Leyva et al 2019;Chenni et al 2020;Hoffmeister et al 2020); a repellent (Ermişler 2017); a protector against bacterial and fungal spoilage (Atifa et al 2020); a natural antioxidant (Hikmawenti et al 2019); a food preservative (Szymandera-Buszka et al 2020;Kerimoğlu et al 2020) and as a feed additive in livestock (Ibrahim et al 2019).…”