Physiological and transcriptomic analysis provide novel insight into cobalt stress responses in willow

Area of Science:

• Plant Biology
• Environmental Toxicology
• Molecular Biology

Background:

• Cobalt (Co) is vital for enzymes but toxic at high concentrations.
• Plant molecular responses to cobalt stress, particularly in woody species, are not well understood.

Purpose of the Study:

• To investigate the morphological, physiochemical, and molecular responses of weeping willow (Salix babylonica) seedlings to cobalt stress.
• To elucidate the defense mechanisms plants employ to tolerate excess cobalt.

Main Methods:

• Morphological and physiochemical measurements.
• RNA sequencing (RNA-seq) analysis to identify differentially expressed genes (DEGs).
• Analysis of physiological and biochemical indexes and metal ion concentrations.

Main Results:

• Cobalt stress significantly altered growth rate, chlorophyll and soluble sugar content, photosynthesis, and peroxidase activity in willow seedlings.
• Cobalt stress disturbed concentrations of essential metal ions like copper (Cu), zinc (Zn), and magnesium (Mg).
• RNA-seq identified 2002 differentially expressed genes (DEGs), with 1165 root-specific and 837 stem/leaf-specific, revealing complex transcriptomic responses including oxidative stress, phytohormone signaling, and ion detoxification.

Conclusions:

• Weeping willow seedlings activate multifaceted defense strategies involving physiological adjustments and intricate gene expression networks to cope with cobalt stress.
• These findings offer comprehensive insights into plant tolerance mechanisms against excessive cobalt, crucial for understanding plant responses in contaminated environments.