Split personality of a Potyvirus: to specialize or not to specialize?

Area of Science:

• Plant Virology
• Molecular Evolution
• Genomics

Background:

• Bean yellow mosaic virus (BYMV), a Potyvirus, exhibits a wide host range across dicots and monocots.
• Previous research suggested phylogenetic groups evolved from a generalist ancestor, with recombination driving host specialization.
• Newer whole-genome analyses identified nine BYMV groups (I-IX), challenging earlier host-based classifications.

Purpose of the Study:

• To investigate the role of recombination in the evolution of BYMV phylogenetic groups.
• To determine if recombination contributes to host specialization or host range expansion in BYMV.

Main Methods:

• Phylogenetic analysis of 33 BYMV whole genomes and two Clover yellow vein virus (CYVV) genomes.
• Recombination analysis conducted on the complete coding regions of these viral genomes.

Main Results:

• Twelve recombination events were detected within BYMV groups I-VI, with no events in groups VII-IX or CYVV.
• Groups I, II, and IV (formerly the generalist group) showed the highest number of recombination events (2-3 each).
• Groups III, V, and VI also exhibited recombination (1 event each), while groups VII-IX showed none.

Conclusions:

• Recombination explains the broad host ranges of BYMV groups I, II, and IV, which infect both monocots and dicots.
• Recombination in BYMV groups III, V, and VI suggests a potential for reduced host specificity and broadened host ranges.
• These findings challenge the hypothesis that recombination drives host specialization in BYMV, supporting its role in host range expansion.