Phenotypic diploidization in plant functional traits uncovered by synthetic neopolyploids inDianthus broteri

Abstract

Whole-genome duplication and post-polyploidization genome downsizing play key roles in the evolution of land plants; however, the impact of genomic diploidization on functional traits still remains poorly understood. Using Dianthus broteri as a model, we compared the ecophysiological behaviour of colchicine-induced neotetraploids (4xNeo) to diploids (2x) and naturally occurring tetraploids (4xNat). Leaf gas-exchange and chlorophyll fluorescence analyses were performed in order to asses to what extent post-polyploidization evolutionary processes have affected 4xNat. Genomic diploidization and phenotypic novelty were evident. Distinct patterns of variation revealed that post-polyploidization processes altered the phenotypic shifts directly mediated by genome doubling. The photosynthetic phenotype was affected in several ways but the main effect was phenotypic diploidization (i.e. 2x and 4xNat were closer to each other than to 4xNeo). Overall, our results show the potential benefits of considering experimentally synthetized versus naturally established polyploids when exploring the role of polyploidization in promoting functional divergence.

Polyploidy promotes divergent evolution across the leaf economics spectrum and plant edaphic niche in the Dianthus broteri complex

“…Most of the variation in the edaphic niche of D. broteri would be explained by processes associated with the short‐term effects of polyploidization as suggested the global structures found in the two main soil‐pPCA axes. The immediate phenotypic novelties derived from genome duplication, such as those found in D. broteri synthetic neotetraploids for several functional traits similar to the ones explored in this study (gas‐exchange and photochemical variables; Domínguez‐Delgado et al., 2021), would be the main drivers of the divergence in soil niche. However, an early post‐polyploidization character displacement caused by competition for niche space (Beans, 2014) or niche filling cannot be ruled out.…”

“…However, we would have expected the leaf nutrients to be increased in the polyploids based on the greater need for these in taxa with larger genomes (Leitch & Leitch, 2008) and the complex polygenic uptake mechanisms for essential macronutrients (N, P and K; Lea & Azevedo, 2006; Vance et al., 2003; Véry & Sentenac, 2003), which would be facilitated by post‐polyploidization processes (Cheng et al., 2018). This finding could be explained by the phenotypic diploidization phenomenon, an evolutionary tendency of returning to diploid‐like phenotype which has been recently demonstrated for photosynthetic characteristics of established D. broteri 4× individuals (Domínguez‐Delgado et al., 2021).…”

“…Only pPCA axes with significant phylogenetic signal are represented. Models are ranked according to their Akaike information criterion (AIC) weight Delgado et al, 2021), would be the main drivers of the divergence in soil niche. However, an early post-polyploidization character displacement caused by competition for niche space (Beans, 2014) or niche filling cannot be ruled out.…”

Evaluation of Reference Genes in the Polyploid Complex Dianthus broteri (Caryophyllaceae) Using qPCR

“…Accordingly, an increased amount and variation in epigenetic marks have been shown in Dianthus broteri [49]. In addition, a moderate genomic diploidization was evident in the different cytotypes of Dianthus broteri as regards the loss of monoploid genome size [26,50]. The phenotypic diploidization found in several functional traits also suggests that purifying selection is acting in this polyploid complex [50].…”

“…In addition, a moderate genomic diploidization was evident in the different cytotypes of Dianthus broteri as regards the loss of monoploid genome size [26,50]. The phenotypic diploidization found in several functional traits also suggests that purifying selection is acting in this polyploid complex [50]. Therefore, the dosage compensation of the selected reference genes could have also been driven by selection to maintain the genomic balance.…”