title: Genome diversity in wild grasses under environmental stress.
abstract: Patterns of diversity distribution in the Isa defense locus in wild-barley populations suggest adaptive selection at this locus. The extent to which environmental selection may act at additional nuclear-encoded defense loci and within the whole chloroplast genome has now been examined by analyses in two grass species. Analysis of genetic diversity in wild barley (Hordeum spontaneum) defense genes revealed much greater variation in biotic stress-related genes than abiotic stress-related genes. Genetic diversity at the Isa defense locus in wild populations of weeping ricegrass [Microlaena stipoides (Labill.) R. Br.], a very distant wild-rice relative, was more diverse in samples from relatively hotter and drier environments, a phenomenon that reflects observations in wild barley populations. Whole-chloroplast genome sequences of bulked weeping ricegrass individuals sourced from contrasting environments showed higher levels of diversity in the drier environment in both coding and noncoding portions of the genome. Increased genetic diversity may be important in allowing plant populations to adapt to greater environmental variation in warmer and drier climatic conditions.
authors.affiliation: Southern Cross Plant Science, Plant Genomics, Southern Cross University, Lismore, NSW 2480, Australia.
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Fitzgerald
authors.forename: Frances M
authors.initials: FM
authors.lastname: Shapter
authors.forename: Stuart
authors.initials: S
authors.lastname: McDonald
authors.forename: Daniel L E
authors.initials: DL
authors.lastname: Waters
authors.forename: Ian H
authors.initials: IH
authors.lastname: Chivers
authors.forename: Andre
authors.initials: A
authors.lastname: Drenth
authors.forename: Eviatar
authors.initials: E
authors.lastname: Nevo
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Henry
mesh_terms: D001483:Base Sequence; D002980:Climate; D018742:DNA, Chloroplast / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics; D004777:Environment; D014644:Genetic Variation; D018745:Genome, Plant / Q000235:genetics*; D007557:Israel; D008969:Molecular Sequence Data; D006109:Poaceae / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012987:Soil / Q000032:analysis; D013045:Species Specificity; D013312:Stress, Physiological / Q000235:genetics*; D014739:Victoria
chemical_list: D018742:DNA, Chloroplast; D012987:Soil