Salinity Adaptation and the Contribution of Parental Environmental Effects in Medicago truncatula.

Ken S Moriuchi,Mohamed Elarbi Aouani,Eric J B Von Wettberg,Sergey V Nuzhdin,Mounawer Badri,Sharon Y Strauss,Maren L Friesen,Bradley J Main,Matilde A Cordeiro,Wendy T Vu,Raffaella Balestrini

doi:10.1371/journal.pone.0150350

Ken S Moriuchi, Mohamed Elarbi Aouani + Show 9 more

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https://doi.org/10.1371/journal.pone.0150350

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Abstract

High soil salinity negatively influences plant growth and yield. Some taxa have evolved mechanisms for avoiding or tolerating elevated soil salinity, which can be modulated by the environment experienced by parents or offspring. We tested the contribution of the parental and offspring environments on salinity adaptation and their potential underlying mechanisms. In a two-generation greenhouse experiment, we factorially manipulated salinity concentrations for genotypes of Medicago truncatula that were originally collected from natural populations that differed in soil salinity. To compare population level adaptation to soil salinity and to test the potential mechanisms involved we measured two aspects of plant performance, reproduction and vegetative biomass, and phenological and physiological traits associated with salinity avoidance and tolerance. Saline-origin populations had greater biomass and reproduction under saline conditions than non-saline populations, consistent with local adaptation to saline soils. Additionally, parental environmental exposure to salt increased this difference in performance. In terms of environmental effects on mechanisms of salinity adaptation, parental exposure to salt spurred phenological differences that facilitated salt avoidance, while offspring exposure to salt resulted in traits associated with greater salt tolerance. Non-saline origin populations expressed traits associated with greater growth in the absence of salt while, for saline adapted populations, the ability to maintain greater performance in saline environments was also associated with lower growth potential in the absence of salt. Plastic responses induced by parental and offspring environments in phenology, leaf traits, and gas exchange contribute to salinity adaptation in M. truncatula. The ability of plants to tolerate environmental stress, such as high soil salinity, is likely modulated by a combination of parental effects and within-generation phenotypic plasticity, which are likely to vary in populations from contrasting environments.

Highlights

Plants experience a range of environmental stresses from different sources and of varying magnitudes [1,2]
Soil salinity concentrations (0 or 100 mM NaCl) were manipulated during the parental and offspring generations for 39 genotypes of Medicago truncatula originally collected from two saline and two non-saline environments in Tunisia
Salinity adaptation was influenced by parental environment with saline origin plants expressing significantly greater vegetative biomass under salt only when the parent generation experienced saline conditions (Fig 1A and 1B)

Summary

Introduction

Plants experience a range of environmental stresses from different sources (e.g., drought, heavy metals, low-nutrient soils) and of varying magnitudes [1,2]. The ability of some plants to maintain vegetative growth and reproduction despite environmental stress suggests that adaptations can evolve within populations. These responses can be genetically fixed within a population resulting in local adaptation. If stressors vary on a smaller spatial scale relative to the range of offspring dispersal, genotypes that have the ability to adjust their phenotypes to match their environment may be favored, i.e., plasticity may evolve in these populations [13,14,15]. When the stressors vary on a larger scale than the range of offspring dispersal, favored alleles may become fixed within populations resulting in population specific adaptations to their home environment [14]

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