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An appreciation of the genetic diversity retained in the gene pool of anemone‐type chrysanthemums is needed to drive further genetic improvement of this commercially important ornamental species. Here, a panel of 67 accessions was characterized with respect to both floral morphology, assessed using a set of 12 inflorescence‐associated traits, and to genotype, using sequence‐related amplified polymorphism (SRAP) fingerprinting. Abundant variation and a high level of broad‐sense heritability (>88%) were revealed for all traits except number of tubular floret lobes. Of the possible 66 pairwise inter‐trait combinations, 37 proved to be significantly correlated. A principal component analysis of the trait data showed that the first four principal components explained ~78% of the variance; meanwhile a hierarchical clustering analysis revealed a number of discrete groups reflecting the various cultivated types, but was not predictive of provenance. The SRAP genotyping employed 22 primer combinations and generated 238 informative fragments. A moderately high level of the Jaccard's similarity coefficient (mean 0.67) was calculated for the examined panel. A hierarchical clustering analysis based on the genotypic data revealed four groups, which were clearly reflective of cultivated type; moreover, a comparison of the within‐cluster means for each of the two key anemone‐related traits—tubular floret length and tubular floret length/style length—showed that the genotype‐based clusterings were associated with the anemone levels, albeit imperfectively. A principal coordinate analysis showed that the first two coordinates accounted for about 14% of the total variation. In summary, the present study adds new understanding of the genetic diversity present in the anemone‐type chrysanthemum gene pool, and the findings will lay the foundation for implementing a genotype/phenotype association strategy to reveal the genetic and molecular basis of floral form in this valuable ornamental species. [ABSTRACT FROM AUTHOR]

Low temperature is a major stress factor that has adverse effects on chrysanthemum production; however, there is little information regarding the genetic mechanism of cold tolerance. Based on a previously constructed F1 mapping population, genetic variations and QTL effects were investigated for cold tolerance at the vegetative, bud, flower, and rhizome stages. The results showed that the coefficient of variation for cold tolerance at the four growth stages ranged from 22.17 to 46.14%, and heterosis and transgressive segregation were observed in both directions. Mixed inheritance model analysis revealed that cold tolerance at the vegetative and flower stages was controlled by two pairs of major genes that exhibited additivity-dominance-epistasis effects, and the heritabilities of the major genes were 88.56% and 65.86%, whereas no major gene model was identified for cold tolerance at the bud and rhizome stages. A total of 15 cold-tolerance-associated QTLs that explained 6.47–68.89% of the phenotypic variation were detected across the four stages, four of which were synergistic QTLs. Most of the identified QTLs were expressed at 2–4 growth stages, but only one QTL was identified at all four stages. This finding indicated that the QTLs underlying cold tolerance were dependent on the environment and were selectively expressed at different stages. In addition, for cold tolerance at the bud and flower stages, the QTLs qBdsCTM33 and qFfsCTM33 on the M33 linkage group accounted for 65.78% and 68.89% of the phenotypic variation, respectively, but had corresponding negative additive effects of − 5.16 and − 4.57 °C, indicating that these QTLs are major contributors to the improvement of cold tolerance. The findings of the present study reveal the genetic architecture of cold tolerance at different developmental stages, and the major QTLs and linked molecular markers identified represent an important step toward molecular-marker-assisted selection and QTL pyramiding for future breeding of cold-tolerant chrysanthemum. [ABSTRACT FROM AUTHOR]

The original article unfortunately contains an incorrect article type. [ABSTRACT FROM AUTHOR]

An anemone shape featuring elongated and pigmented disk florets is an important target in breeding for flower shape in chrysanthemum. A good understanding of the inheritance of anemone-related traits and specific molecular markers are vital for accelerating the breeding progress. In this study, two segregating intercultivar F1 populations of the anemone-type 'Nannong Xuefeng' × the nonanemone-type 'QX096' (80 lines) and the same anemone-type 'Nannong Xuefeng' × 'Monalisa' (144 lines) were employed to investigate the genetic variation of anemone traits, and the anemone-specific markers were developed via the bulked segregant analysis (BSA) method by constructing two extreme bulks from each 10 anemone-type and nonanemone-type F1 lines, respectively. A moderate high level of variation coefficient (~ 24 to 57%) was obtained for most tubular floret traits relevant to the anemone type in both segregating populations. The anemone morphology of the hybrids was intermediate between that of their parents, and some transgressive individuals were observed, indicating great potential for the selection of lines with the desirable anemone type. In the BSA, four sequence-related amplified polymorphism (SRAP) primer combinations were identified as informative between the bulks of the anemone and nonanemone F1 individuals. After cloning and sequencing, only one SRAP marker, i.e., M11E1_272, was successfully converted to the sequence-characterized amplified region (SCAR) marker SCAR168. The SCAR marker was validation in the two F1 populations demonstrated that the marker SCAR168 could truly discriminate anemone and nonanemone types with a high coincidence ratio 87.86~92.5%. In addition, a general linear model (GLM)-based association analysis (P < 0.01) revealed that the SCAR marker exhibited a positive effect on the anemone traits and explained 20.83~33.66% phenotypic variation. Results of the current study show the inheritance pattern of anemone traits, and the developed anemone-specific SCAR marker paves the way for the marker-assisted selection of flower shape in chrysanthemum. [ABSTRACT FROM AUTHOR]