Unité de Recherche Vignes et Vins de Champagne - EA 4707, SFR Condorcet FR CNRS 3417, UFR Sciences Exactes et Naturelles, Université de Reims Champagne-Ardenne, 51687, Reims, France.
Photosynth Res. 2017 Nov;134(2):201-214. doi: 10.1007/s11120-017-0435-2. Epub 2017 Aug 24.
Pathogen infection of plant results in modification of photosynthesis and defense mechanisms. Beneficial microorganisms are known to improve plant tolerance to stresses. Burkholderia phytofirmans PsJN (Bp), a beneficial endophytic bacterium, promotes growth of a wide range of plants and induces plant resistance against abiotic and biotic stresses such as coldness and infection by a necrotrophic pathogen. However, mechanisms underlying its role in plant tolerance towards (hemi)biotrophic invaders is still lacking. We thus decipher photosynthetic and defense responses during the interaction between Arabidopsis, Bp and the hemibiotrophic bacterium Pseudomonas syringae pv. tomato DC3000 (Pst). Different Bp inoculations allowed analyzes at both systemic and local levels. Despite no direct antibacterial action, our results showed that only local presence of Bp alleviates Pst growth in planta during the early stage of infection. Molecular investigations showed that seed inoculation of Bp, leading to a restricted presence in the root system, transiently primed PR1 expression after challenge with Pst but continuously primed PDF1.2 expression. Bacterization with Bp reduced Y(ND) but had no impact on PSII activity or RuBisCO accumulation. Pst infection caused an increase of Y(NA) and a decrease in ΦPSI, ETRI and in PSII activity, showed by a decrease in Fv/Fm, Y(NPQ), ΦPSII, and ETRII values. Inoculation with both bacteria did not display any variation in photosynthetic activity compared to plants inoculated with only Pst. Our findings indicated that the role of Bp here is not multifaceted, and relies only on priming of defense mechanisms but not on improving photosynthetic activity.
病原体感染植物会导致光合作用和防御机制的改变。有益微生物被认为可以提高植物对压力的耐受能力。植物根内定殖菌 Burkholderia phytofirmans PsJN（Bp）是一种有益的内生细菌，它可以促进广泛的植物生长，并诱导植物对非生物和生物胁迫的抗性，如寒冷和坏死性病原体的感染。然而，其在植物对（半）生物性病原体入侵的耐受作用中的机制仍不清楚。因此，我们解析了拟南芥、Bp 和半生物性细菌丁香假单胞菌 pv.番茄 DC3000（Pst）之间相互作用过程中的光合作用和防御反应。不同的 Bp 接种方式允许在系统和局部水平上进行分析。尽管 Bp 没有直接的抗菌作用，但我们的结果表明，只有在感染早期局部存在 Bp 才能减轻 Pst 在植物体内的生长。分子研究表明，Bp 的种子接种导致根系内的限制存在，在受到 Pst 挑战后会短暂地引发 PR1 的表达，但会持续地引发 PDF1.2 的表达。Bp 的细菌化减少了 Y(ND)，但对 PSII 活性或 RuBisCO 积累没有影响。Pst 感染导致 Y(NA)增加和 ΦPSI、ETRI 和 PSII 活性降低，表现为 Fv/Fm、Y(NPQ)、ΦPSII 和 ETRII 值降低。与仅接种 Pst 的植物相比，同时接种两种细菌不会导致光合作用活性发生任何变化。我们的研究结果表明，Bp 在这里的作用不是多方面的，仅依赖于防御机制的激活，而不是提高光合作用活性。
