Phenotypic differences among and within extant populations of Chrysanthemum arcticum L. and C. a. subsp. arcticum

Abstract

AbstractBackgroundChrysanthemum arcticum, arctic daisy and its two subspecies (Chrysanthemum arcticumsubsp.arcticum,Chrysanthemum arcticumsubsp.polaré) are the only chrysanthemum species native to North America. A study on species’ variation in morphological and diagnostic traits is important to link morphological traits with previously described single nucleotide polymorphism (SNP) markers, particularly when the genomes are sequenced. The purpose of this study was to establish phenotypic differences and soil conditions among wildC. arcticumandC. a.subsp.arcticumpopulations, when grown in a uniform environment for two years, for potential linkages with our SNP library. Sixteen quantitative morphological traits and five qualitative morphological traits were investigated for 255 individuals from nineC. arcticumpopulations and 326 individuals from 21C. a.subsp.arcticumpopulations.ResultsIn long-day controlled environment,C. arcticumflowering rate was 0% in Year 1, increased to 2.7% in Year 2, whileC. a.subsp.arcticumflowering rate was 98.5% in Year 2. Two distinct clusters, distributed by taxonomic classification, were detected by Principal component analysis (PCoA) for 551 individuals fromC. arcticumandC. a.subsp.arcticum.Pearson’s correlation coefficient analysis indicated a positive and significant correlation between plant height, flower fresh and dry weights. Flower fresh weights were correlated with Δflower weight, while inflorescence length had showed a negative correlation with leaf number. Soil samples had high Na levels along with heavy metals. Thus, the species are salt-tolerant.ConclusionA high level of salt tolerance (Na) is tolerated by these maritime species which is a unique trait inChrysanthemum. A new diagnostic trait of inflorescence length was discovered to distinguish amongC. arcticumandC. a.subsp.arcticum.Significant flowering differences occurred among the speciesC. arcticumandC. a.subsp.arcticumunder same photoperiodic environment, including flowering rates and visible bud date. This study on the species’ variation in morphological and diagnostic traits is of importance to link morphological traits with single nucleotide polymorphism (SNP) markers.