A Root-Colonizing Pseudomonad Lessens Stress Responses in Wheat Imposed by CuO Nanoparticles

Area of Science:

• Agricultural Science
• Environmental Science
• Microbiology

Background:

• Nanoparticles (NPs) with essential metals are explored as fertilizers for nutrient-deficient soils.
• Copper oxide nanoparticles (CuO NPs) can negatively impact plant growth and physiology.
• Understanding plant-microbe interactions is crucial for managing NP effects in agriculture.

Purpose of the Study:

• To investigate if Pseudomonas chlororaphis O6 (PcO6) colonization protects wheat roots from growth inhibition by CuO NPs.
• To assess the impact of PcO6 on CuO NP-induced stress responses in wheat roots.
• To determine if PcO6 influences copper bioavailability and uptake in wheat.

Main Methods:

• Wheat seedlings were grown with and without PcO6 colonization in the presence of CuO NPs.
• Root elongation, bacterial cell density, reactive oxygen species (ROS) levels, and plant stress gene expression were measured.
• Rhizosphere solution analysis for chelator levels and soluble copper was performed.
• Copper content in wheat leaves was quantified.

Main Results:

• A trend for slightly improved root elongation was observed with PcO6 colonization under CuO NP stress.
• PcO6 colonization reduced the expression of plant stress-responsive genes induced by CuO NPs.
• PcO6 reduced citric and malic acid levels in the rhizosphere, potentially by utilizing them as nutrients.
• Trends indicated lower soluble copper in the rhizosphere and reduced copper accumulation in leaves with PcO6.

Conclusions:

• Root colonization by PcO6 modulates wheat's response to CuO NPs.
• Bacterial modulation of plant stress pathways and copper bioavailability may offer a protective effect.
• These findings highlight the potential of beneficial bacteria in mitigating nanoparticle toxicity in agricultural systems.