Evidence for a primary role of active oxygen species in induction of host cell death during infection of bean leaves withBotrytis cinerea
Evidence for a primary role of active oxygen species in induction of host cell death during infection of bean leaves withBotrytis cinerea
复制标题
DOI：
10.1006/pmpp.1996.0076
复制
发表时间：
1997-03
影响因子：
2.7
通讯作者：
A. Tiedemann
中科院分区：
文献类型：
--
作者：
A. Tiedemann
摘要选择对氧化剂敏感性高或低的菜豆基因型（菜豆）对臭氧、百草枯和灰霉病菌感染表现出相似的胁迫反应。在漂浮在稀释的麦芽肉汤培养基中并接种B分生孢子的菜豆叶圆片上研究了真菌攻击的潜在氧化性质。在攻击性上不同的灰霉病菌分离物。在感染过程中原位测量过氧化氢和OH* 自由基。此外，过氧化物酶，纤维素酶，木聚糖酶和多聚半乳糖醛酸酶（PG）扩散到孵育培养基在感染过程中进行了分析。基于2-脱氧核糖的氧化降解的测定使得能够特异性检测原位产生的OH* 自由基。6个葡萄孢菌菌株的致病力与侵染过程中叶片组织中H2 O2和OH* 自由基的产生量密切相关。侵略性菌株诱导的OH* 自由基形成的峰值信号在24小时内和强烈升高的水平H2 O 2在48小时内接种后（HPI），在一个阶段的最迅速进展的感染。在非攻击性相互作用中没有检测到活性氧（AOS）的增加。与未接种的叶盘相比，所有测试的真菌分离物抑制植物过氧化物酶活性。然而，侵略性菌株显着更抑制比非侵略性的，这表明过氧化物酶在植物抗性中的作用，作为有害的AOS的清除剂。过氧化氢的生产在受感染的叶盘测量强于其在培养介质中的积累，指向植物内的H2 O2的来源。AOS、过氧化氢酶和D-甘露醇的清除剂显著降低了感染的严重程度。纤维素酶和木聚糖酶的分泌发生晚于感染的开始，这表明这些细胞壁降解酶在消化死的而不是杀死活的宿主组织中的作用。PG产生的所有真菌菌株早得多（12 hpi），但生产没有反映分离的侵略性。这是第一个直接原位检测B侵染植物组织过程中有毒AOS的研究。灰色区域。因此，AOS除了可能在植物抗性中发挥作用外，还可能对B等坏死营养型生物起作用。灰霉病在感染的初始阶段杀死宿主组织。
Abstract Bean genotypes ( Phaseolus vulgaris ) selected for high or low sensitivity to oxidants showed similar stress responses to ozone, paraquat and to infection with Botrytis cinerea . The potentially oxidative nature of the fungal attack was investigated on bean leaf discs floated in diluted malt broth medium and inoculated with conidia of B. cinerea isolates differing in aggressiveness. Hydrogen peroxide and OH* radicals were measured in situ during infection. Additionally, peroxidases, cellulases, xylanases and polygalacturonases (PG) diffusing into the incubation medium during infection were analysed. An assay based on the oxidative degradation of 2-deoxyribose enabled the specific detection of in situ generated OH* radicals. The aggressiveness of six isolates of Botrytis was closely correlated with the amount of H 2 O 2 and OH* radicals detected in the leaf tissue during infection. Aggressive isolates induced peak signals of OH* radical formation within 24 h and strongly elevated levels of H 2 O 2 within 48 h post-inoculation (hpi), in a phase of most rapidly progressing infection. No such increases in active oxygen species (AOS) were detected in non-aggressive interactions. All fungal isolates tested suppressed plant peroxidase activity as compared to non-inoculated leaf discs. However, aggressive isolates were significantly more suppressive than non-aggressive ones, suggesting a role for peroxidases in plant resistance as scavengers of harmful AOS. Hydrogen peroxide production measured in infected leaf discs was stronger than its accumulation in the incubation medium, pointing to sources of H 2 O 2 inside the plant. The scavengers of AOS, catalase and D-mannitol significantly reduced severity of infection. Secretion of cellulases and xylanases occurred later than the start of infection, suggesting a role of these cell-wall degrading enzymes in the digestion of dead rather than the killing of living host tissue. PGs were produced by all fungal isolates much earlier (12 hpi) but the production did not reflect the isolate aggressiveness. This is the first study to directly detect toxic AOS in situ during infection of plant tissue by B. cinerea . It is concluded that AOS, besides their probable role in plant resistance, might be instrumental for necrotrophs like B. cinerea to kill the host tissue in initial stages of infection.