Comparative transcriptomics reveals context- and strain-specific regulatory programmes of Agrobacterium during plant...

Area of Science:

• Microbiology
• Plant Pathology
• Genomics

Background:

• Agrobacterium is crucial for plant genetic engineering via Agrobacterium-mediated transformation.
• Limited understanding of wild-type Agrobacterium strain diversity and their regulatory responses.
• Model strain C58 is extensively studied, but may not represent the full spectrum of Agrobacterium capabilities.

Purpose of the Study:

• Evaluate wild-type Agrobacterium strains for superior tumorigenesis and transformation efficiency.
• Characterize transcriptional responses of Agrobacterium 1D1108 under in vitro and in planta conditions.
• Compare gene expression profiles with model strains to understand strain-specific regulation.

Main Methods:

• Screened five wild-type Agrobacterium strains for tumorigenesis on legumes and transient transformation in Nicotiana benthamiana.
• Induced virulence in vitro using acetosyringone and performed RNA sequencing to identify differentially expressed genes (DEGs).
• Analyzed in planta transcriptomes after leaf infiltration and compared with model strains C58 and Pseudomonas syringae DC3000.

Main Results:

• Agrobacterium strain 1D1108 demonstrated superior tumorigenesis and transient transformation capabilities.
• Identified 126 DEGs in 1D1108 under in vitro conditions, with only 22 conserved with C58, indicating significant divergence.
• Discovered 1,134 DEGs specifically regulated in planta for 1D1108, including genes for attachment, virulence, and nutrient transport.
• Comparative transcriptomics revealed distinct secretion systems (Type IV for Agrobacterium, Type III for Pseudomonas) and low DEG conservation (~5-19%) between pathogens.

Conclusions:

• Agrobacterium strain 1D1108 is a promising candidate for improved plant genetic engineering applications.
• Significant genetic divergence exists among Agrobacterium strains, necessitating strain-specific studies.
• In planta gene expression reveals unique colonization strategies shaped by host-associated cues.
• Understanding strain-specific transcriptomic responses is critical for accurate insights into bacterial pathogenesis and plant-microbe interactions.