Desiccation Tolerance Evolved through Gene Duplication and Network Rewiring in Lindernia

Area of Science:

• Plant biology
• Evolutionary genomics
• Molecular genetics

Background:

• Understanding the evolution of desiccation tolerance in resurrection plants is limited by a lack of suitable dehydration-sensitive outgroups.
• Genomic insights into desiccation tolerance require comparative analyses between related tolerant and sensitive species.

Purpose of the Study:

• To identify gene and pathway-level changes associated with the evolution of desiccation tolerance.
• To utilize a comparative system of closely related desiccation-tolerant (Lindernia brevidens) and -sensitive (Lindernia subracemosa) species.

Main Methods:

• Assembly of two high-quality Lindernia genomes.
• Comparative differential gene coexpression analysis across dehydration, desiccation, and rehydration time courses.
• Analysis of gene duplications, neofunctionalization, and cis-regulatory elements.

Main Results:

• High collinearity and gene conservation (>90%) between L. brevidens and L. subracemosa genomes.
• Evidence of ancient whole-genome duplication and neofunctionalization, with desiccation-specific expression in L. brevidens.
• Dramatic expansion of early light-induced proteins and enrichment of Late Embryogenesis Abundant (LEA) genes in L. brevidens.
• Extensive network rewiring and upregulation of seed-associated genes in L. brevidens during desiccation, linked to seed-specific and abscisic acid-associated cis-regulatory elements.

Conclusions:

• Desiccation tolerance evolved through a combination of gene duplications and network-level rewiring.
• Existing seed desiccation pathways were repurposed and enhanced in the desiccation-tolerant species.
• Comparative genomics provides a powerful approach to understanding the evolution of complex traits like desiccation tolerance.