Evolution of cold tolerance in the highly stress-tolerant samphires and relatives (Salicornieae: Amaranthaceae)

Abstract Low temperature constitutes one of the main barriers to plant distributions, confining many clades their ancestrally tropical biome. However, recent evidence suggests that transitions from temperate biomes may be more frequent than previously thought. Here, we study evolution cold and frost tolerance in globally distributed highly stress-tolerant Salicornieae (Salicornioideae, Amaranthaceae s.l.). We first generate a phylogenetic tree comprising almost all known species (85-90%), using newly generated (n = 106) published nuclear-ribosomal plastid sequences. Next, use geographical occurrence data document which regions cold-tolerant occur reconstruct how evolved. Finally, test for correlated between annual life form. find has evolved independently up four Northern Hemisphere lineages but annuals are no likely evolve perennials, indicating presence different strategies adapting environments. Our findings add mounting multiple independent out-of-the-tropics among close relatives flowering plants raise new questions about ecological physiological mechanism(s) adaptation low temperatures Salicornieae.