Transcriptional Responses to Priority Effects in Nectar Yeast

Area of Science:

• Ecology
• Microbial Ecology
• Molecular Ecology

Background:

• Priority effects, where arrival order influences community assembly, are widespread but their genetic underpinnings are poorly understood.
• Nectar yeasts, like Metschnikowia reukaufii, commonly inhabit floral nectar and can experience strong priority effects.
• Understanding the molecular basis of these effects is crucial for predicting community dynamics.

Purpose of the Study:

• To investigate the genetic and molecular basis of priority effects in the nectar yeast Metschnikowia reukaufii.
• To determine how the presence of another yeast species, Metschnikowia rancensis, affects M. reukaufii gene expression and fitness.

Main Methods:

• Whole-transcriptome sequencing of 108 M. reukaufii strains.
• Experimental inoculation into synthetic nectar simulating prior M. rancensis colonization.
• Analysis of gene expression quantitative trait loci (eQTLs).

Main Results:

• Differential gene expression in M. reukaufii when exposed to nectar conditioned by M. rancensis.
• Upregulated genes were predominantly associated with amino acid metabolism, indicating a response to nutrient limitation.
• Genetic variants influencing amino acid transport and antifungal resistance were identified, correlating with population growth rates under nutrient limitation.

Conclusions:

• Intraspecific genetic variation in nutrient acquisition and competitive ability underlies priority effects in nectar yeast communities.
• Molecular responses to resource competition and fungal interactions are key drivers of microbial community assembly.
• This study provides a molecular framework for understanding priority effects in a natural microbial system.