Assistant professor Louisiana State University Baton Rouge, Louisiana
Body of Abstract: Soil salinization is a major threat to global food security as it reduces arable land and limits available water for crops. All crops are generally sensitive to high salinity and salt stress can lead to complete crop failure or severe yield losses. However, extremophytes adapted to high salinity as well as other extreme environmental conditions have evolved multiple genetic, biochemical, and structural adaptations to survive high salinity. Previous studies have shown that salt tolerance has convergently evolved in multiple angiosperm lineages. Yet, there is a large knowledge gap in linking convergently evolved genes or gene networks governing phenotypic traits that enable salt tolerance. With the growing number of genomes and transcriptomes available from extremophytes as well as salt-sensitive species in relevant sister clades, we have explored genomic and transcriptomic level convergence to discover the underlying salt tolerance-associated genes and pathways. We used sequence data for >500 angiosperm genomes and transcriptomes to identify orthologous gene groups in a custom pipeline that systematically assembled, annotated, and aligned gene families. We identified gene family expansion in key genes associated with ABA regulation and salt transport in multiple extremophytes distantly related to each other suggesting strong signals of convergent evolution. Additionally, we found constitutive high expression of key regulatory genes known to improve salt tolerance in the extremophytes compared to their salt-sensitive sister species indicative of gene expression convergence at the transcriptome level. These results highlight repeated evolutionary innovations in diverse angiosperm lineages that may allow us to select genes and pathways that are optimal candidates for improving salt tolerance in diverse crops better adapted to extreme and changing climates.