Phenotypic plasticity of polyploid plant species promotes transgressive behaviour in their hybrids.

Blanca Gallego-Tévar,Enrique Figueroa,Jesús M Castillo,Brenda J Grewell,Alfonso De Cires,Alfredo E Rubio-Casal

doi:10.1093/aobpla/ply055

Blanca Gallego-Tévar, Enrique Figueroa + Show 4 more

Open Access

https://doi.org/10.1093/aobpla/ply055

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Abstract

Hybridization is a frequent process that leads to relevant evolutionary consequences, but there is a lack of studies regarding the relationships of the variability of the response of parental plant species to environmental gradients and the responses of their hybrids at a phenotypic level. We designed an experiment in which we exposed two reciprocal cordgrass hybrids, Spartina maritima × densiflora and S. densiflora × maritima, and their parental species to four salinity concentrations for 30 days. The main objectives were to compare the performance of the hybrids with that of their parents, to distinguish the phenotypic inheritance operating in the hybrids and to analyse the relationships between the variability in the responses of the parents and the responses of their hybrids to salinity. We characterized the responses and the degree of variability for 37 foliar traits. Both hybrids presented greater salinity tolerance than their parents, showing their highest percentage of transgressive traits at both extremes of the salinity gradient. When the parental plants themselves showed a more plastic response for a given trait, there was a greater chance that their hybrid developed a transgressive behaviour for this trait. This finding supports a new focus to be applied for the artificial development of vigorous hybrid crops.

Highlights

Hybridization is a frequent process in both plants and animals that leads to relevant evolutionary and ecological consequences (Arnold 1992)
The pigments content of S. maritima exceeded that of S. densiflora only at hypersalinity
The greater tolerance of both Spartina hybrids to salinity than their parental species highlights the relevance of heterosis in hybridization processes

Summary

Introduction

Hybridization is a frequent process in both plants and animals that leads to relevant evolutionary and ecological consequences (Arnold 1992). The ecological performance of hybrids depends on the expression of genes that control traits related to their stress tolerance and fitness (Chen 2013). The novel genotypes obtained by hybridization commonly exhibit phenotypic traits with intermediate values between both parents due to an additive genetic control when the traits are controlled by a large number of genes that act independently, AoB PLANTS https://academic.oup.com/aobpla. In addition to the genomic mechanisms, recent studies have revealed the importance of epigenetic changes in key genes regulating fitness-related traits in hybrids (Salmon et al 2005; Ni et al 2009). There is evidence that a greater genetic differentiation between parents results in greater heterosis in their hybrids (East 1936; Chen 2010)

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