In vitro production of pycnidia by Septoria tritici

Abstract

The in vitro production of pycnidia by Septoria tritici was examined on six media reported to induce the formation of fruiting bodies. Among 26 freshly isolated cultures from various parts of the world, consistent differences in growth type were found which were only partially influenced by nutritional and environmental conditions. Cultures with yeast-like growth produced hardly any pycnidia or pseudopycnidia, while cultures with intermediate or mycelial growth types produced them frequently. Incubation in continuous darkness induced intermediate to mycelial growth types rather than yeast-like growth types in some cultures, and concomitantly the production of more pycnidia. Potato-dextrose agar induced intermediate to mycelial growth types and production of (pseudo)pycnidia more often than V8 agar and wheat leaf extract agar, which had previously been reported to be especially beneficial to (pseudo) pycnidium formation by S. tritiei. Isolates with a consistently yeast-like growth type, producing (virtually) no fructifications under any of the experimental conditions, were slightly stimulated to form pseudopycnidia on water agar supplemented with sterile pieces of maize, wheat or carnation leaves.Additional keywords." speckled leaf blotch, wheat, growth type, pseudopycnidia.

The occurrence of Mycosphaerella graminicola, teleomorph of Septoria tritici in France

“…Cultures were whitish to pink, convoluted yeast-like colonies, with black stroma-like structures and without formation of typical pycnidia. This is in accordance with observations of Hilu & Bever (1957), Djerbi et al (1974) and Kema & Annone (1991).…”

Durum Wheat Quality, Yield and Sanitary Status under Conservation Agriculture

“…In subsequent observations, no further formation of cirrhi from the pycnidia present on the damaged leaves was noticed. The subsequent observations of cirrhi under the microscope confirm the presence of conidia, morphologically attributable to Zymoseptoria tritici [32,33] ( Figure 2B). The crushing on the slide of the pycnidia, taken at 72-96 h, in the damaged leaf portions, and the subsequent observation under the microscope, did not allow us to observe any propagation element inside the corpuscle ( Figure 2C).…”

“…In seasons with low rain at the end of the crop cycle (2017), cirrhi developed from pycnidia located on the leaves were very scarce [32,57], inducing a decrease in the cycles of infection; nevertheless, the late disease appearance seems to be the main reason for the low effect on yields, as demonstrated in 2016, when climate conditions were favourable to disease symptom expression [57].…”

The MAP kinase‐encoding gene MgFus3 of the non‐appressorium phytopathogen Mycosphaerella graminicola is required for penetration and in vitro pycnidia formation

“…Indeed, it has been shown that pycnidia are extensively melanized, suggesting that melanin is required for asexual fructification in M. graminicola (Duncan and Howard, 2000; Kema et al ., 1996; Mehrabi et al ., 2006). This may explain the failure to produce pycnidia in vitro , although this process is also influenced by other cultural conditions (Kema and Annone, 1991). In other filamentous plant pathogens, MgFus3 orthologues are essential in various stages of development, including vegetative growth, conidiation and germination of conidia (Lev et al ., 1999; Takano et al ., 2000; Zheng et al ., 2000).…”