Genome‐material costs and functional trade‐offs in the autopolyploid Solidago gigantea (giant goldenrod) series

Abstract

AbstractPremiseIncreased genome‐material costs of N and P atoms inherent to organisms with larger genomes have been proposed to limit growth under nutrient scarcities and to promote growth under nutrient enrichments. Such responsiveness may reflect a nutrient‐dependent diploid versus polyploid advantage that could have vast ecological and evolutionary implications, but direct evidence that material costs increase with ploidy level and/or influence cytotype‐dependent growth, metabolic, and/or resource‐use trade‐offs is limited.MethodsWe grew diploid, autotetraploid, and autohexaploid Solidago gigantea plants with one of four ambient or enriched N:P ratios and measured traits related to material costs, primary and secondary metabolism, and resource‐use.ResultsRelative to diploids, polyploids invested more N and P into cells, and tetraploids grew more with N enrichments, suggesting that material costs increase with ploidy level. Polyploids also generally exhibited strategies that could minimize material‐cost constraints over both long (reduced monoploid genome size) and short (more extreme transcriptome downsizing, reduced photosynthesis rates and terpene concentrations, enhanced N‐use efficiencies) evolutionary time periods. Furthermore, polyploids had lower transpiration rates but higher water‐use efficiencies than diploids, both of which were more pronounced under nutrient‐limiting conditions.ConclusionsN and P material costs increase with ploidy level, but material‐cost constraints might be lessened by resource allocation/investment mechanisms that can also alter ecological dynamics and selection. Our results enhance mechanistic understanding of how global increases in nutrients might provide a release from material‐cost constraints in polyploids that could impact ploidy (or genome‐size)‐specific performances, cytogeographic patterning, and multispecies community structuring.