Variation in Oidium neolycopersici development on host and non‐host plant species and their tissue defence responses

Abstract

SummaryDetailed studies of the infection processes of Oidium neolycopersici (tomato powdery mildew) and plant tissue responses were carried out on 10 Lycopersicon spp. accessions and one of each species of Cucumis sativus, Datura stramonium, Lactuca sativa, Petunia hybrida and Pisum sativum with different levels of resistance. Germination of O. neolycopersici conidia was not inhibited by the host plant. However, in the early stages of O. neolycopersici infection significant differences in conidial germ tube development on resistant and susceptible plant lines were observed. The first substantial differences appeared after 24 h post inoculation (hpi). Mycelia and conidiophores developed on susceptible lines; however, there was no mycelial development on resistant plant lines. The most frequent resistant response in Lycopersicon species was the necrotic (hypersensitive) reaction (HR), occasionally followed by pathogen development. The completely resistant accession L. hirsutum (LA 1347) showed only a limited number of necrotic host cells per infection site (2%). In Oidium resistant tomato lines OR 4061 and OR 960008 the existence of adult resistance was detected. This phenomenon occurred mainly in accession OR 4061. Rapid development and profuse sporulation of O. neolycopersici was observed on juvenile plants (6–8 wk old), however this was in contrast to the slow development and sporadic sporulation observed on 4 month old plants. Evidence of posthaustorial resistance was observed in the interaction of O. neolycopersici with non‐host species (Lactuca sativa and Pisum sativum.) This was in contrast to Datura stramonium and Petunia hybrida, where development of powdery mildew was delayed at a later stage in the infection cycle. With the exception of Pisum sativum, the necrotic (hypersensitive) response was observed often.

Resistance mechanisms of wild tomato germplasm to infection of Oidium neolycopersici

“…Also for the interaction between non-host plants and O. neolycopersici, it was concluded (Huang et al 2000a) that resistance was not based on inhibition of formation of primary haustorium, but on post-haustorial HR and another type of nonhypersensitive resistance. This was confirmed by Mieslerová et al (2004) who found no effective prehaustorial resistance. For a better understanding of this phenomenon we need a more detailed study of its biochemical and molecular background.…”

“…The second stage plant-pathogen interaction is represented by colonisation of plant tissue, including cell responses. Experiments by Mieslerová et al (2004) showed that O. neolycopersici stopped its development on non-host plants (Lactuca sativa and Pisum sativum) early after the first appressoria and haustoria formed in plant cells. Huang et al (2000a) observed intensive cell necrosis (hypersensitivity) in lettuce after inoculation with O. neolycopersici, which was in contrast with the observations of Mieslerová et al (2004).…”

“…Interactions between non-host and host plants and O. neolycopersici were studied in detail (Huang et al 1997(Huang et al , 1998(Huang et al , 2000aLebeda andMieslerová 1999, 2000;Mieslerová et al 2004) from the viewpoint of histology, cytology and biochemistry. However, the phenomenon of non-host resistance is not very well understood.…”

“…have been carried out (Huang et al 1998;Jones et al 2000;Lebeda and Mieslerová 2000;Mieslerová et al 2004). All authors agree that early after inoculation germination was observed starting between 3 and 6 h post inoculation (hpi) Mieslerová et al 2004); or before 17 hpi (Huang et al 1998).…”

“…Later attention was focused on study of resistance mechanims after infection of O. neolycopersici at the histological, biochemical and photosynthetic level (Huang et al 1998;Mieslerová et al 2004;Mlíčková et al 2004;Tománková et al 2006;Piterková et al 2009Piterková et al , 2011Prokopová et al 2010;Nožková-Hlaváčková et al, submitted). Research in the last 15 years has broadened knowledge of the genetic basis of resistance to O. neolycopersici (Lindhout et al 1994b;Ciccarese et al 1998;Huang et al 2000b;Bai et al 2003Bai et al , 2004Bai et al , 2005Li et al 2006Li et al , 2007Li et al , 2008Li et al , 2012Seifi et al 2013).…”