Non‐host resistance of barley is associated with a hydrogen peroxide burst at sites of attempted penetration by wheat powdery mildew fungus

Abstract

Summary In barley, non-host resistance against the wheat powdery mildew fungus (Blumeria graminis f.sp. tritici, Bgt) is associated with the formation of cell wall appositions and a hypersensitive reaction in which epidermal cells die rapidly in response to fungal attack. In the interaction of barley with the pathogenic barley powdery mildew fungus (Blumeria graminis f.sp. hordei, Bgh), these defence reactions are also associated with accumulation of H(2)O(2). To elucidate the mechanism of non-host resistance, the accumulation of H(2)O(2) in response to Bgt was studied in situ by histochemical staining with diaminobenzidine. H(2)O(2) accumulation was found in cell wall appositions under appressoria from Bgt and in cells undergoing a hypersensitive reaction. A mutation (mlo5) at the barley Mlo locus, that confers broad spectrum resistance to Bgh, did not influence the barley defence phenotype to Bgt. Significantly, Bgt triggered cell death on mlo5-barley while Bgh did not.

Reactive oxygen intermediates in plant-microbe interactions: Who is who in powdery mildew resistance?

“…Moreover, H 2 O 2 patterns in non-host resistance of barley to wheat powdery mildew fungus (Blumeria graminis f.sp. tritici) qualitatively resemble those of background and race-specific resistance (Hu¨ckelhoven et al 2001b; M. Trujillo: unpublished results from our laboratory).…”

Arabidopsis Cell Death in Compatible and Incompatible Interactions with Alternaria brassicicola

“…Phenotypically, cell death is a prerequisite in the compatible interaction between Arabidopsis and A. brassicicola. Lesion mimic mutants, such as barley mlo, show a broad-spectrum disease resistance against biotrophic pathogens but are highly susceptible to necrotrophic pathogens (Aviv et al, 2002;Huckelhoven et al, 2001;Jarosch et al, 2003;Salmeron and Vernooij, 1998;Yao et al, 2009;Yin et al, 2000). This ambivalence further supports the opposing contribution of PCD to the interaction.…”

Antifungal defenses of seagrasses from the Indian River Lagoon, Florida

“…Fungal pathogens can elicit the production of reactive oxygen species (ROS), such as superoxide radical (O 2 À ), hydroxyl radical (OH ) and hydrogen peroxide (H 2 O 2 ) in a variety of terrestrial plants (Huckelhoven et al, 2001;Huckelhoven and Kogel, 2003). This rapid production of ROS, termed the oxidative burst, is triggered within minutes of infection (Apel and Hirt, 2004).…”

“…Fungal pathogens have been demonstrated to elicit the production of reactive oxygen species (ROS), such as superoxide radical (O 2 À ), hydroxyl radical (OH ) and hydrogen peroxide (H 2 O 2 ) (Huckelhoven et al, 2001;Huckelhoven and Kogel, 2003). Aside from functioning as a direct toxic agent against invading microbes, ROS have been demonstrated to be a critical component of the plant-pathogen hypersensitive response involved in cell wall strengthening (Otte and Barz, 1996), the activation of defense genes (Jabs et al, 1997), caspase activation (Ge et al, 2005) and the establishment of programmed cell death, which results in the limitation of pathogen penetration and propagation (Levine et al, 1994;Lamb and Dixon, 1997).…”