Surface interactions of Fusarium graminearum on barley

Abstract

The filamentous fungus Fusarium graminearum, a devastating pathogen of barley (Hordeum vulgare L.), produces mycotoxins that pose a health hazard. To investigate the surface interactions of F. graminearum on barley, we focused on barley florets, as the most important infection site leading to grain contamination. The fungus interacted with silica-accumulating cells (trichomes and silica/cork cell pairs) on the host surface. We identified variation in trichome-type cells between two-row and six-row barley, and in the role of specific epidermal cells in the ingress of F. graminearum into barley florets. Prickle-type trichomes functioned to trap conidia and were sites of fungal penetration. Infections of more mature florets supported the spread of hyphae into the vascular bundles, whereas younger florets did not show this spread. These differences related directly to the timing and location of increases in silica content during maturation. Focal accumulation of cellulose in infected paleae of two-row and six-row barley indicated that the response is in part linked to trichome type. Overall, silica-accumulating epidermal cells had an expanded role in barley, serving to trap conidia, provide sites for fungal ingress and initiate resistance responses, suggesting a role for silica in pathogen establishment.

Deoxynivalenol-3-Glucoside Content Is Highly Associated with Deoxynivalenol Levels in Two-Row Barley Genotypes of Importance to Canadian Barley Breeding Programs

“…While resistant to spread, barley is susceptible for an extended period following spike emergence, where cleistogamous (closed-flowered) genotypes accumulated more mycotoxins when inoculated 10 or 20 days after anthesis [22]. Recently, trichomes of palea and lemma have been highlighted as structural targets for susceptibility in later-stage infections [48]. Trichomes of rachis tissues have been previously hypothesized as an invasion point that could be used to overcome the strong Type II resistance of barley through external growth of mycelia over the epidermis [18].…”

Building on a foundation: advances in epidemiology, resistance breeding, and forecasting research for reducing the impact of fusarium head blight in wheat and barley

“…Stomata or injury points may also provide the fungus with alternative stochastic entry routes. Silica cells associated with trichomes of lemma and palea can be directly penetrated and may also be vulnerable to later infection in barley (Imboden et al 2018). Fusarium infection in barley can occur over a twoweek period following heading, where this extended period can increase the chances of exposure to events with favourable infection conditions (McCallum and Tekauz 2002).…”

Relationship between genetic variability of flowering traits andFusariummycotoxin contamination in oats

“…Of more importance were differences in mycotoxin content between genotypes like Tim (low DON content) and Bessin (high DON content) or Keely (low DON content) and Scorpion (high DON content) with similar PH, AR, and BBCH in Panel 2. Possible reasons for such differences were detoxification of DON (Michlmayr et al, 2018) or a variation in trichome-type cells, which were found to be related to Fusarium ingress and resistance responses in barley (Imboden, Afton, & Trail, 2018).…”