Environmental niche variation and evolutionary diversification of the <i>Brachypodium distachyon</i> grass complex species in their native circum‐Mediterranean range

López-Álvarez, Diana; Manzaneda, Antonio J.; Rey, Pedro J.; Giraldo, Patricia; Benavente, Elena; Allainguillaume, Joël; Mur, Luis A. J.; Caicedo, Ana L.; Hazen, Samuel P.; Breiman, Adina; Ezrati, Smadar; Catalán, Pilar

doi:10.3732/ajb.1500128

Cited by 79 publications

(113 citation statements)

References 86 publications

(149 reference statements)

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“…Brachypodium distachyon occurs across a mosaic of landscapes (Lopez‐Alvarez et al ., ). Our results reveal that this variation in habitats leads to natural selection, which affected different genes and genomic regions across populations.…”

Section: Discussionmentioning

confidence: 97%

Genome‐wide scans of selection highlight the impact of biotic and abiotic constraints in natural populations of the model grass Brachypodium distachyon

et al. 2018

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Grasses are essential plants for ecosystem functioning. Quantifying the selective pressures that act on natural variation in grass species is therefore essential regarding biodiversity maintenance. In this study, we investigate the selection pressures that act on two distinct populations of the grass model Brachypodium distachyon without prior knowledge about the traits under selection. We took advantage of whole-genome sequencing data produced for 44 natural accessions of B. distachyon and used complementary genome-wide selection scans (GWSS) methods to detect genomic regions under balancing and positive selection. We show that selection is shaping genetic diversity at multiple temporal and spatial scales in this species, and affects different genomic regions across the two populations. Gene ontology annotation of candidate genes reveals that pathogens may constitute important factors of positive and balancing selection in B. distachyon. We eventually cross-validated our results with quantitative trait locus data available for leaf-rust resistance in this species and demonstrate that, when paired with classical trait mapping, GWSS can help pinpointing candidate genes for further molecular validation. Thanks to a near base-perfect reference genome and the large collection of freely available natural accessions collected across its natural range, B. distachyon appears as a prime system for studies in ecology, population genomics and evolutionary biology.

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Section: Discussionmentioning

confidence: 97%

Genome‐wide scans of selection highlight the impact of biotic and abiotic constraints in natural populations of the model grass Brachypodium distachyon

et al. 2018

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“…c). Interestingly, the diploid annual species B. stacei is smaller and found at lower elevations with more xeric conditions than B. distachyon (López‐Alvarez et al ., ).…”

Section: Discussionmentioning

confidence: 99%

Interactive effects of water limitation and elevated temperature on the physiology, development and fitness of diverse accessions of Brachypodium distachyon

et al. 2016

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An enduring question in plant physiology and evolution is how single genotypes of plants optimize performance in diverse, often highly variable, environments. We grew 35 natural accessions of the grass Brachypodium distachyon in four environments in the glasshouse, contrasting soil water deficit, elevated temperature and their interaction. We modeled treatment, genotype and interactive effects on leaf-level and whole-plant traits, including fecundity. We also assessed the relationship between glasshouse-measured traits and parameters related to climate at the place of origin. We found abundant genetic variation in both constitutive and induced traits related to plant-water relations. Most traits showed strong interaction between temperature and water availability, and we observed genotype-by-environment interaction for several traits. Notably, leaf free proline abundance showed a strong effect of genotype × temperature × water. We found strong associations between phenology, biomass and water use efficiency (WUE) with parameters describing climate of origin. Plants respond to multiple stressors in ways not directly predictable from single stressors, underscoring the complex and trait-specific mechanisms of environmental response. Climate-trait correlations support a role for WUE and phenology in local adaptation to climate in B. distachyon.

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“…are self–fertile grasses (Vogel et al, ) comprised of three different species; B. distachyon, B. stacei and B. hybridum . Each of these three species is a different karyotype (López‐Alvarez et al, ; López‐Alvarez et al, ): the two species, B. distachyon (2 n = 10, 0.631 pg/2C) and B. stacei (2 n = 20, 0.564 pg/2C) are diploid species with relatively small genomes, while B. hybridum (2 n = 30, 1.265 pg/2C) is a derived allotetraploid with a larger genome size (Catalán et al, ). These species share similar DNA content, differing only in the number of chromosomes due to multiple centric fusion/fission events (Catalán et al, ).…”

Section: Introductionmentioning

confidence: 99%

Phenology and polyploidy in annualBrachypodiumspecies (Poaceae) along the aridity gradient in Israel

Penner

Dror

Aviezer

et al. 2019

J of Sytematics Evolution

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Local adaptation of plants along environmental gradients provides strong evidence for clinal evolution mediated by natural selection. Plants have developed diverse strategies to mitigate stress, for example, drought escape is a phenological strategy to avoid drought stress, while polyploidy was proposed as a genomic adaptation to stress. Polyploidy as an adaptation to aridity (an environmental parameter integrating temperature and precipitation) was previously documented in annual Brachypodium spp. (Poaceae) in the Western Mediterranean. Here, we examined whether polyploidy or phenology are associated with aridity in annual Brachypodium spp. along the aridity gradient in the Eastern Mediterranean. Using flow cytometry, we determined ploidy levels of plants from natural populations along the Israeli gradient, spanning ∼424 km from mesic Mediterranean to extreme desert climates. In a common garden we recorded time of seedling emergence, flowering and senescence. We tested whether the proportion of allotetraploids in the populations and phenological traits were associated with aridity. Contrary to a previous study in the Western Mediterranean, we found no effect of aridity on the proportion of allotetraploids and diploids within populations. Interestingly, phenology was associated with aridity: time of emergence was later, while flowering and senescence were earlier in desert plants. Our results indicate that in the Eastern Mediterranean, adaptation of Brachypodium to aridity is mediated mainly by phenology, rather than ploidy level. Therefore, we suggest that genome duplication is not the main driver of adaptation to environmental stress; rather, phenological change as a drought escape mechanism may be the major adaptation.

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Environmental niche variation and evolutionary diversification of the Brachypodium distachyon grass complex species in their native circum‐Mediterranean range

Cited by 79 publications

References 86 publications

Genome‐wide scans of selection highlight the impact of biotic and abiotic constraints in natural populations of the model grass Brachypodium distachyon

Genome‐wide scans of selection highlight the impact of biotic and abiotic constraints in natural populations of the model grass Brachypodium distachyon

Interactive effects of water limitation and elevated temperature on the physiology, development and fitness of diverse accessions of Brachypodium distachyon

Phenology and polyploidy in annualBrachypodiumspecies (Poaceae) along the aridity gradient in Israel

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