Impact of genome duplications in drought tolerance and distribution of the diploid-tetraploid Jasione maritima

Abstract

Polyploidy has important ecological effects, including ploidy-mediated effects on morphology, breeding system and ecological tolerances. However, there is still little comprehensive research available to test its adaptive significance and its role in driving distributional patterns. This work aimed to assess the contribution of genome duplications to ecological divergence using an experimental approach with the diploid-tetraploid Jasione maritima polyploid complex. We explored if individuals with different ploidy differ in their tolerance to water deficit and if this may contribute to explaining the distribution patterns along a latitudinal gradient in the northwest Iberian Peninsula. For that, we used three cytogenetic entities: diploids and established tetraploids collected in natural populations along a latitudinal gradient, and neotetraploids synthesized from diploid populations after treatments with colchicine. Thirty plants from each of the nine populations were grown under controlled conditions with half randomly assigned to the water deficit treatment, and half used as control. We determined experimental plants’ response by measuring fitness-related parameters, such as above and belowground biomass, plant water status, photosynthetic efficiency and pigments, membrane stability, antioxidant capacity and sugars content. Our data shows that biomass, chlorophyll content, photochemical quenching (qP) and non-photochemical quenching (NPQ) in neotetraploids and established tetraploids were significantly higher than in diploids and that these differences could be attributed to genome duplications. In response to the water deficit, diploids seem to use a strategy of avoidance, whereas tetraploids seem to employ the strategy of tolerance to overcome water deficit stress, which appears equally efficient. Additionally, we did not observe a response pattern along the latitudinal gradient of the distributional range of the J. maritima complex. The results indicate that the response to water deficit is population dependent. Further studies are necessary to understand the role of ploidy in explaining the distribution patterns of the J. maritima complex.

Competitive ability, neopolyploid establishment and current distribution of a diploid–tetraploid plant complex

“…Also, the lack of consistency between the biomass results obtained here and in Castro et al (2023a) is likely related to the length of the experiment. Here, the experiment was conducted until flowering (for eight months), while in Castro et al (2023a) the experiment lasted for three and a half months. Thus, it is likely that the effect of having bigger body sizes in neotetraploids is lost in latter stages, not because cells reduce their size but because they eventually multiply in slower rate.…”

“…On the one hand, without competition, neotetraploids were more similar to established tetraploids (except for belowground biomass) and were smaller overall than diploids. This trend is unexpected as genome duplications are usually associated with the ‘gigas effect' (Stebbins 1971, Buggs and Pannell 2007, Hoya et al 2007, Ramsey and Ramsey 2014) and because, in previous studies, diploid J. maritima had lower biomasses (Castro et al 2023a) and higher stomatal density with lower sizes than neotetraploids (Siopa et al 2020). Also, the lack of consistency between the biomass results obtained here and in Castro et al (2023a) is likely related to the length of the experiment.…”

“…This trend is unexpected as genome duplications are usually associated with the ‘gigas effect' (Stebbins 1971, Buggs and Pannell 2007, Hoya et al 2007, Ramsey and Ramsey 2014) and because, in previous studies, diploid J. maritima had lower biomasses (Castro et al 2023a) and higher stomatal density with lower sizes than neotetraploids (Siopa et al 2020). Also, the lack of consistency between the biomass results obtained here and in Castro et al (2023a) is likely related to the length of the experiment. Here, the experiment was conducted until flowering (for eight months), while in Castro et al (2023a) the experiment lasted for three and a half months.…”

“…Data are available from the Dryad Digital Repository: https:// doi.org/10.5061/dryad.wm37pvmt2 (Castro et al 2023b).…”

Special issue.: The role of whole genome duplication in evolutionary ecology

“…In addition to differences in interactions that relate to reproductive isolation, other types of interactions may also be altered in ways that confer an advantage to polyploids over diploids. Reductions in parasites (Walczyk and Hersch-Green 2024), resistance to pathogens (Hagen and Mason 2024), increased competitive ability (Castro et al 2024), and specialized interactions with mutualists (Gerstner et al 2024) could give polyploids an edge that facilitates their establishment.…”