LEM, Institut de Biologie des Plantes, Université Paris Diderot, Sorbonne Paris Cité, Orsay, France.
J Appl Microbiol. 2012 Apr;112(4):782-92. doi: 10.1111/j.1365-2672.2012.05248.x. Epub 2012 Feb 20.
The early molecular events underlying the elicitation of plant defence reactions by Gram-positive bacteria are relatively unknown. In plants, calcium and reactive oxygen species are commonly involved as cellular messengers of a wide range of biotic stimuli from pathogenic to symbiotic bacteria. In the present work, we checked whether nonpathogenic Streptomyces sp. strains could induce early signalling events leading to defence responses in BY2 tobacco cell suspensions.
We have demonstrated that nonpathogenic Streptomyces sp. OE7 strain induced a cytosolic Ca(2+) increase and a biphasic oxidative burst in the upstream signalling events, leading to defence responses in BY2 tobacco cell suspensions. Streptomyces sp. OE7 also elicited delayed intracellular free scopoletin production and programmed cell death. In agreement with scopoletin production, OE7 induced accumulation of PAL transcripts and increased accumulation of transcripts of EREBP1 and AOX genes that are known to be regulated by the jasmonate/ethylene pathway. Transcript levels of PR1b and NIMIN2α, both salicylic acid pathway-linked genes, were not modified. Moreover, Streptomyces sp. OE7 culture filtrates could reduce Pectobacterium carotovorum- and Pectobacterium atrosepticum-induced death of BY2 cells and soft rot on potato slices.
New insights are thus provided into the interaction mechanisms between Streptomyces sp. and plants; Streptomyces sp. could be sensed by plant cells, and through cytosolic Ca(2+) changes and the generation of reactive oxygen species, defence responses were induced.
These induced defence responses appeared to participate in attenuating Pectobacterium-induced diseases in plants. Thus, Streptomyces sp. OE7 could be a biocontrol agent against Pectobacterium sp.
革兰氏阳性细菌诱导植物防御反应的早期分子事件尚不清楚。在植物中，钙和活性氧通常作为从病原细菌到共生细菌的各种生物刺激的细胞信使参与。在本工作中，我们检查了非致病性链霉菌菌株是否可以诱导导致防御反应的早期信号事件在 BY2 烟草细胞悬浮液中。
我们已经证明，非致病性链霉菌 OE7 菌株诱导了细胞溶质 Ca(2+)增加和双相氧化爆发，在 BY2 烟草细胞悬浮液的上游信号事件中导致防御反应。链霉菌 OE7 还引发了延迟的细胞内游离伞形酮的产生和程序性细胞死亡。与伞形酮的产生一致，OE7 诱导 PAL 转录物的积累，并增加 EREBP1 和 AOX 基因的转录物积累，这些基因已知受茉莉酸/乙烯途径调控。PR1b 和 NIMIN2α 的转录物水平，两者均与水杨酸途径相关的基因，没有改变。此外，链霉菌 OE7 培养滤液可减少 Pectobacterium carotovorum 和 Pectobacterium atrosepticum 诱导的 BY2 细胞死亡和马铃薯切片软腐病。
因此，对链霉菌和植物之间的相互作用机制提供了新的见解；链霉菌可以被植物细胞感知，通过细胞质 Ca(2+)变化和活性氧的产生，诱导防御反应。
这些诱导的防御反应似乎参与了减轻植物中果胶杆菌引起的疾病。因此，链霉菌 OE7 可以作为果胶杆菌的生物防治剂。
