Phenotypic landscapes: phenological patterns in wild and cultivated barley

Abstract

Phenotypic variation in natural populations is the outcome of the joint effects of environmentally induced adaptations and neutral processes on the genetic architecture of quantitative traits. In this study, we examined the role of adaptation in shaping wild barley phenotypic variation along different environmental gradients. Detailed phenotyping of 164 wild barley (Hordeum spontaneum) accessions from Israel (of the Barley1K collection) and 18 cultivated barley (H. vulgare) varieties was conducted in common garden field trials. Cluster analysis based on phenotypic data indicated that wild barley in this region can be differentiated into three ecotypes in accordance with their ecogeographical distribution: north, coast and desert. Population differentiation (Q ST ) for each trait was estimated using a hierarchical Bayesian model and compared to neutral differentiation (F ST ) based on 42 microsatellite markers. This analysis indicated that the three clusters diverged in morphological but not in reproductive characteristics. To address the issue of phenotypic variation along environmental gradients, climatic and soil gradients were compared with each of the measured traits given the geographical distance between sampling sites using a partial Mantel test. Flowering time and plant growth were found to be differentially correlated with climatic and soil characteristic gradients, respectively. The H. vulgare varieties were superior to the H. spontaneum accessions in yield components, yet resembled the Mediterranean types in vegetative characteristics and flowering time, which may indicate the geographical origin of domesticated barley.

Correlations between Circadian Rhythms and Growth in Challenging Environments

“…The longer period at both high and low MDT8 might reflect a constricted growing season at both extremes. Consistent with the idea that temperature at the site of origin may be a selection force on photoperiodic flowering, strong correlations between flowering time and MDT1 have been reported for the B1K lines (Hübner et al, 2013). Although in our experiments we measured circadian rhythms in constant light and in natural conditions plants grow under daily light/dark (diel) conditions, it is possible that the differences we observed in period length may affect the expression of photoperiod components in diel conditions.…”

“…We have reported previously that, in Arabidopsis, when plants are grown under stressful high-density conditions, the next generation has higher amplitude rhythms, suggesting that the stressful conditions may select for amplitude (Yerushalmi et al, 2011). Supporting the idea that the selective force of the environmental conditions may impact different aspects of barley growth and development, Db at the site of origin is strongly correlated with plant size but not with flowering time in the B1K wild barley lines (Hübner et al, 2013).…”

Large Differences in Gene Expression Responses to Drought and Heat Stress between Elite Barley Cultivar Scarlett and a Spanish Landrace

“…However, they worked with wild barley, whereas this study employed a landrace and an elite cultivar. Wild barley holds much more diversity than cultivated types, with considerable variation in physiological and phenotypic characteristics, and presents specific environmental adaptations to stress like temperature and rainfall (Ellis et al, 2000; Hübner et al, 2013). Therefore, it is feasible that the responses to abiotic stresses of wild barley are different to those of cultivated genotypes.…”

Root traits contributing to plant productivity under drought

“…Moreover, alleles contributing to more extensive root growth and distribution may be present in cultivated varieties of rice rather than in wild species if observations from container-grown plants hold (Liu et al, 2004). Introgression of alleles from modern varieties reduces the negative effects of linkage drag from the use of wild species and landraces (Hübner et al, 2013). Nonetheless, landrace varieties for certain species may also show potential for introgression of genetic diversity into modern varieties.…”