Nigeran synthesis by regenerating protoplasts of Aspergillus awamori correlates with formation of hyphae

SummaryTo show the involvement of microfilaments and microtubules in non-host resistance of barley, partially dissected coleoptiles which had been inoculated with a non-pathogen, Erysiphe pisi, were treated with several actin and tubulin inhibitors. If the coleoptiles were not treated with any of the inhibitors, the non-pathogen always failed to penetrate the coleoptile cells. However, when coleoptiles were treated with actin or tubulin polymerization or depolymerization inhibitors, the non-pathogen was able to penetrate successfully and to form haustoria in coleoptlie cells of a non-host plant, barley. Actin polymerization inhibitors, cytochalasins, were more effective in causing an increase in penetration efficiency of E. pisithan tubulin inhibitors. The effects of cytochalasins depended on the kind of cytochalasin; the strength of the actin depolymerizing activity correlated significantly with the efficiency of increasing the penetration of the non-pathogen. When both actin and tubulin inhibitors were added simultaneously, the polarization of defense-related responses, such as massive cytoplasmic aggregation, deposition of papillae and accumulation of autofluorescent compounds, at fungal penetration sites was suppressed. Actin inhibitors did not affect arrangement and stability of microtubules and vice versa, and a double treatment of coleoptile cells with both microfilament and microtubule inhibitors showed an additive effect in increasing the penetration efficiency of E. pisL Furthermore, cytochalasin A treatment allowed other non-pathogens, Colletotrichum lagenarium and Alternaria alternata, to penetrate successfully into the non-host barley cells. These results strongly suggest that microfilaments and microtubules might play important roles in the expression of non-host resistance of barley.

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“…Cell viability was determined by staining with fluorescein diacetate (FDA) (Douglas et al, 1984) 24 h after treatment with inhibitors.…”

Section: Treatment With Inhibitorsmentioning

confidence: 99%

Dynamic reorganization of microfilaments and microtubules is necessary for the expression of non‐host resistance in barley coleoptile cells

Kobayashi²,

et al. 1997

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“…During early development of the giant cell of A. niger, a-1,3-glucan was elaborated in the cell wall as well as an alternating a-1,3and a-1,4-polymer, commonly referred to as nigeran (38). The latter, at least in regenerating protoplasts, is incorporated as a secondary wall polymer after synthesis of other wall polymers or attainment of a particular cell shape or both (122). During microcycle conidiation, a-1,3-glucan and its synthetic enzyme decreased in concentration toward the end of stage 1, while nigeran remained firmly constant and a-glucanase showed a marked increase.…”

Section: Biochemical Eventsmentioning

confidence: 99%