Inhibition of the hypersensitive reaction in barley to powdery mildew by heat shock and cytochalasin B

The Cytoskeleton as a Regulator and Target of Biotic Interactions in Plants

“…Cytoplasmic aggregation is an example of sitedirected cytoplasmic streaming and is dependent upon the action of the actin component of the cytoskeleton, as was shown in the early 1980s using inhibitors of actin polymerization (Tomiyama et al, 1982;Hazen and Bushnell, 1983). Complementing the pharmacological experiments, a variety of cytochemical labeling studies, including recent observations of living cells in which actin microfilaments were labeled with a green fluorescent protein (GFP)-tagged actin-binding protein, have revealed radial focusing of actin microfilaments on the pathogen penetration site in many plant-pathogen interactions (Figs.…”

“…This conclusion is consistent with results of pharmacological studies with actin or microtubule polymerization/depolymerization inhibitors. It has been shown that in addition to effects on cytoplasmic aggregation and papilla formation (Kobayashi et al, 1997b;Škalamera et al, 1997), cytochalasins (inhibitors of actin polymerization) suppress or delay other resistance reactions such as hypersensitive cell death ( Tomiyama et al, 1982;Hazen and Bushnell, 1983;Škalamera and Heath, 1998;Takemoto et al, 1999) and pathogenesis related protein expression (Takemoto et al, 1999). Cytochalasin treatment also permits nonpathogens to penetrate barley coleoptile cells and form secondary hyphae (Kobayashi et al, 1997b) and, in combination with the eds1 (enhanced disease susceptibility1) mutation in Arabidopsis, allows Blumeria graminis (syn.…”

Heat shock, with recovery, promotes protection of Nicotiana tabacum during subsequent exposure to Ralstonia solanacearum

“…Induction of Hsp70/Hsc70 in this scenario was accompanied by protection of e − transport and increased apoptosis as measured by PS externalization and DNA fragmentation. This phenomenon has implications for defense responses to avirulent bacteria, which is overruled by concomitant HS (Hazen and Bushnell 1983;Malamy et al 1992). This study aimed to illustrate on a cellular level what happens on a daily basis in nature during plant exposure to a combination of temperature and pathogen stress and emphasizes the importance of studying a combination of stresses where the eventual outcome is more than the sum of the individual stresses.…”

Effect of heat-shock pre-treatment on tomato plants infected by powdery mildew fungus

“…Heat-induced susceptibility has also been described in the barley infected by Blumeria (= Erysiphe) graminis f.sp. hordei (Hazen & Bushnell 1983) or in coffee infected by the rust (Silva et al 1992). We anticipate that HS pre-treatment, followed by inoculation and infection process, amplified plant stress to such a great extent, that the leaves lost their turgor and started to necrotise and die much earlier than in the case of infection without HS.…”