Genetic diversity analysis and fingerprints of Chrysanthemum×morifolium based on SSR molecular markers / 生物工程学报

The present study aims to explore the genetic diversity of germplasm resources of Chrysanthemum×morifolium (hereinafter, C.×morifolium) at the molecular level and to establish a fingerprint database of C.×morifolium varieties. We employed 12 pairs of primers with high levels of polymorphism, clear bands, and high degrees of reproducibility to analyze the SSR molecular markers and genetic diversity of 91 C.×morifolium materials and 14 chrysanthemum- related materials. With regard to constructing the fingerprints of the tested materials, we chose 9 pairs of core primers. The findings revealed that 12 primer pairs detected 104 alleles in 105 samples, ranging from 2 to 26. The average number of observed alleles (Na) per site was 9.25. The average number of effective alleles (Ne) per site was 2.745 6, with its range being 1.276 0 to 4.742 5. Shannon genetic diversity index (I) values ranged between 0.513 3 and 2.239 9 (M=1.209 0). Nei's gene diversity index (H) ranged between 0.216 3 and 0.789 1 (M=0.578 0). The observed heterozygosity (Ho) ranged between 0.223 3 and 0.895 2 (M=0.557 5). The expected heterozygosity (He) ranged between 0.217 4 and 0.793 3 (M=0.580 8). The polymorphism information content (PIC) ranged between 0.211 5 and 0.774 0 (M=0.532 9). The genetic similarity (GS) ranged between 0.228 5 and 1.000 0 (M=0.608 3). Cluster analysis revealed that when the genetic distance (GD) equals to 0.30, the tested materials can be classified into 2 groups. When the GD equals to 0.27, the first group can be divided into 6 subgroups; accordingly, 105 tested materials can be divided into 7 subgroups. The cophenetic correlation test was carried out based on the cluster analysis, and the corresponding results showed that the cluster map correlated with the genetic similarity coefficient (r=0.952 73). According to the results of Structure population analysis, we obtained the optimal population number, with the true number of populations (K) being 3 and the population being divided concerning Q≥0.5. Three subgroups, i.e., Q1, Q2 and Q3, included 34, 33 and 28 germplasms, respectively, and the remaining 10 germplasms were identified as the mixed population. During the experiment, 9 pairs of core primers were screened among the total of 12 for a complete differentiation regarding 105 tested materials, and the fingerprints of 91 C.×morifolium materials and 14 chrysanthemum-related materials were further constructed. Overall, there were significant genetic differences and rich genetic diversity among C.×morifolium materials, which would shed light on the garden application and variety selection fields of C.×morifolium. The fingerprint database of 105 C.×morifolium varieties and chrysanthemum-related species may provide technical support for future research regarding the identification and screening system of C.×morifolium varieties.

Research progress of pesticide residues in Chrysanthemum / 中国中药杂志

Chrysanthemum is widely used as a type of edible flower and also considered as the important materials of many beverages in China. Due to the occurrence of diseases and pests, and the lack of regulations for species, frequency, dose of pesticides in Chrysanthemum, pesticides have become one of the main pollutants in Chrysanthemum. The pesticide residues in Chrysanthemum were detected frequently and worth noting. This paper focused on the types of pesticides, pesticide residue detection techniques, and risk assessment methods for Chrysanthemums on the basis of relevant literatures. The pesticide residues of traditional Chinese medicine are mainly organochlorines, organophosphorus and pyrethroids, and the detection techniques include gas chromatography(GC), liquid chromatography(LC) or both combined with mass spectrometry(MS). With the increasing use of traditional Chinese medicine, Chrysanthemum is widely circulated in the market. Therefore, it is important to understand the current situation of pesticide residues in different varieties of Chrysanthemum, so as to provide theoretical reference for the control of quality and safety of Chrysanthemum and the formulation of the maximum residue limit.

Analysis and evaluation of mineral elements of Chrysanthemum morifolium for medicinal and tea use of different germplasm resources / 中国中药杂志

In this study, 23 germplasm resources of Chrysanthemum morifolium used in medicine and tea were collected from Dabie Mountains and its surrounding producing areas, and the contents of 13 mineral elements were determined and compared. The thermal maps of correlation analysis, principal component analysis and cluster analysis were used for comprehensive evaluation. The results showed that the average content of each element in Ch. morifolium of different germplasm resources was: K>N>P>Mg>Ca>Fe>Mn>Zn>Cu>Ni>Cr>Pb>Cd, and the leaves were: K>N>Ca>Mg>P>Fe>Mn>Zn>Cr>Cu>Ni>Pb>Cd. There are rich contents of N, P, K, Ca, Mg and Fe in Ch. morifolium flowers and their leaves, among them, K element has the largest change range, while N, Ca, Fe, Mg and Zn elements have a larger change range. The absorption and accumulation of each element in the leaves of different germplasm resources varied greatly. The correlation analysis shows that there is a strong positive correlation between Ca element, Mg, Mn and Cd element.Principal component analysis in Ch. morifolium flowers characteristic elements for Mn, Cr, Cu, P, K, can be used as a Ch. morifolium resources to identify the characteristics of the elements, choose top five principal component(F1-F5) comprehensive evalua-tion of medicinal Ch. morifolium, scored in the top five varieties for Hangiu-Fuhuangju, Hangju-Xiaoyangju, Hangju-Sheyangju, Hangju-Dayanghua, Hangju-Subeiju,indicates that in terms of mineral elements, the five medicinal Ch. morifolium resources quality is better. The PCA score chart can divide 23 Ch. morifolium resources into 4 groups, and the cluster analysis heat map divides 23 Ch. morifolium resources into 5 groups. All the Ch. morifolium resources of the same type can be well clustered together, indicating that the difference in mineral element content of Ch. morifolium germplasm resources is closely related to genetic factors.

DNA demethylation during Chrysanthemum floral transition following short-day treatment

Background: Analytical techniques such as methylation-sensitive amplification polymorphism and high-performance liquid chromatography were used to detect variation in DNA methylation of mature Chrysanthemum leaves during the floral transition induced by short-day (SD) treatment. Results: For both early- and late-flowering cultivars, the time from the date of planting to the appearance of the capitulum bud and early blooming were significantly shorter than those of the control. The capitulum development of the early-flowering cultivar was significantly accelerated compared to the control, unlike the late-flowering cultivar. The DNA methylation percentage of leaves was significantly altered during flower development. For the early-flowering cultivar, DNA methylation was 42.2-51.3% before the capitulum bud appeared and 30.5-44.5% after. The respective DNA methylation percentages for the late-flowering cultivar were 43.5-56% and 37.2-44.9%. Conclusions: The DNA methylation percentage of Chrysanthemum leaves decreased significantly during floral development. The decline in DNA methylation was elevated in the early-flowering cultivar compared with the late-flowering cultivar.