不同生活型被子植物功能性状与基因组大小的关系

Relationship between functional traits and genome size variation of angiosperms with different life forms

基因组大小在被子植物物种之间存在着巨大的变异,但目前对不同生活型被子植物功能性状与基因组大小的关系缺乏统一的认识。本研究基于被子植物245科2,226属11,215个物种的基因组大小数据,探讨了不同生活型物种种子重量、最大植株高度和叶片氮、磷含量4个功能性状与基因组大小之间的关系。结果表明,被子植物最大植株高度和种子重量与基因组大小间的关系在草本和木本植物中存在显著差异。草本植物最大植株高度与基因组大小的关系不显著,但种子重量与其呈极显著的正相关关系。木本植物最大植株高度与基因组大小显著负相关,但种子重量与其关系不显著。木本植物叶片氮含量与基因组大小呈显著正相关,但其他生活型植物的叶片氮、磷含量与基因组大小均无显著相关性。本研究表明被子植物功能性状与基因组大小的相关性在不同生活型间存在差异,这为深入研究植物多种功能性状和植物生活型与基因组大小的权衡关系在植物演化和生态适应中的作用提供了重要依据。

Aims:The genome size between species,especially in angiosperms,can be extremely diverse.Here,we compiled genome size data for 11,215 angiosperm species from 2,226 genera and 245 families to explore the relationships between four functional traits(i.e.seed mass,maximum plant height,leaf nitrogen and phosphorus concentrations)with genome size in angiosperms from different life forms(i.e.annual herbs,perennial herbs,and woody plants).Method:We used the 1C-value of DNA content as a measurement for genome size.Genome sizes were obtained from the latest version of Kew Plant DNA C-values Database and Genome Size in Asteraceae Database(GSAD).We also complemented our taxon sampling with data from the literature over the past 10 years.We obtained life form and functional trait from Flora of China,Flora of North America and the Seed Information Database(SID).We used the most recent updated time-calibrated phylogeny published by Smith and Brown in 2018,and pruned it to the 6,612 species from our species list.We used two indices(i.e.Blomberg’s K and Pagel’sλ)to test for the prescence of a phylogenetic signal for the evolution of angiosperm genome size.We performed a standardized major axes(SMA)Model II and focused on the relationships between genome size and the four functional traits.We also conducted a principal components analysis(PCA)to explore trade-offs between functional traits and genome size in angiosperms with different life forms.Results:The genome size for most angiosperms was small and few species had large genomes.The median value of angiosperm genome size was 1.58 pg with perennial herbs having the largest median genome size(2.5 pg),followed by annual herbs(1.55 pg),and then woody species(1.14 pg).Variation of the genome size was greatest in perennial herbs distributed over a wider range than woody species and then annual herbs.Tests for phylogenetic signals with genome size indicated that evolution was non-random.The value for Blomberg’s K was 0.031(P<0.001)and the value for Pagel’sλwas 0.943(P<0.001).There was also a significant difference between functional traits and genome size among the three different life forms.Our results from the standardized major axes regression found that there was a significant relationship between seed mass with genome size in herbs but not woody plants.However,the relationship of maximum plant height was significant with genome size in woody plants but not herbs.There were no significant correlations between leaf nitrogen or phosphorus concentration with genome size except for leaf nitrogen concentration in woody plants.When looking at the relationship between four functional traits with genome size,we fund a negative correlation between seed mass and maximum plant height with genome size,and saw no significant correlation with leaf nitrogen or phosphorus concentration which is consistent with the SMA results.Conclusion:Our study highlights that the correlation between functional traits and genome size vary between herbaceous and woody species and suggests that trade-offs between genome size,life forms and functional traits might play an essential role in ecological adaptation and evolution of angiosperms.