Study on Polyphenol Oxidase Activity and Total Phenol Content of Docynia indica

[Objectives] To study the polyphenol oxidase (PPO) activity and total phenol content of Docynia indica .[Methods] The tender branches and petioles of the medicinal and edible plant D. indica were used as experimental materials, and the annual changes of total phenol content and polyphenol oxidase (PPO) activity were analyzed.[Results] pH 7.0 was the optimum value of polyphenol oxidase activity in D. indica plants;the best substrate was catechol with the concentration of 0.15 mol/L;the optimum temperature was 25 ℃.[Conclusions] The total phenol content of D. indica plants was the lowest in April, May and September of each year. The polyphenol oxidase activity of D. indica plants at flowering and fruiting stage was significantly higher than that at pre-flowering stage.

Analysis of Seed Phenotypic and Metabolic Characteristics of Diploid and Tetraploid Tartary Buckwheat

Polyploid plants grow well,are stress tolerant,and are rich in nutrients and bioactive compounds.Thus,they are useful for improving crop quality and yield.In this study,we compared the seed characteristics and metabolite profiles of diploid and tetraploid tartary buckwheat,which was developed via an artificially induced chromosome doubling event.The length,width,area,and thousand-grain weight were greater for the tetraploid seeds than for the diploid seeds.However,the germination rate decreased for the tetraploid seeds.Additionally,there was a gap between the shell and kernel of the tetraploid seeds.Moreover,the water absorption rate was higher for the tetraploid than for the diploid seeds.Chromosome doubling increased the seed total flavonoid content and deepened the seed color.A principal component analysis of the ultrahigh-pressure liquid chromatography-high resolution mass spectrometry data revealed the clear separation between the diploid and tetraploid samples.An orthogonal partial least squares-discriminant analysis and other multivariate statistical analyses identified 83 differentially abundant compounds,with most of the flavonoid metabolites more abundant in the tetraploid than in the diploid seeds.Research on tartary buckwheat polyploidy may result in enhanced germplasm resources and may clarify the mechanism underlying the biosynthesis of bioactive compounds.

Study on Callus Induction and Tissue Culture Regeneration System of Malus toringoides

[Objectives]To study the culture of callus produced by the leaves of the ethnic medicine‘E Se’,the induction of adventitious buds and the regeneration system of tissue culture seedlings.[Methods]Multi-factor orthogonal experiment was used to design and analyze.[Results]The best medium for callus induction was MS+2.0 mg/L 6-BA+0.1 mg/L 2,4-D.By comparing the effects of cytokinin 6-BA,KT and TDZ on induction of adventitious bud differentiation,it was found that the optimum medium for adventitious bud regeneration was MS+0.5 mg/L 6-BA+0.5 mg/L KT+0.15 mg/L IBA.Finally,adding 0.2 mg/L IBA(0.1 or 0.2 mg/L)to MS medium could effectively make regenerated seedlings produce roots,and the efficiency was more than 70%.[Conclusions]It laid a foundation for the large-scale cultivation of the seedlings of the ethnic medicine‘E Se’and the promotion of their artificial cultivation.

Comparative Analysis of the Transcriptome and Metabolome in Leaves of Diploid and Tetraploid Fagopyrum tataricum

Tartary buckwheat(Fagopyrum tataricum)is a dual-purpose medicinal and food crop grown for its high contents of functional compounds and abundant nutrients.Although studies have shown the differences of total flavonoid content in Tartary buckwheat at different ploidy levels,the composition of flavonoid and its regulatory mechanisms are largely unknown.In this study,the leaf metabolome and transcriptome of diploid and tetraploid accessions of Tartary buckwheat were analyzed to gain insight into the impact of polyploidization on comparative secondary metabolite composition and molecular regulatory mechanism.Based on a widely targeted metabolomics analysis,a total of 792 metabolites were identified,including 127 flavonoids.The accumulation of 127 metabolites and expression of 3871 genes differed significantly between diploid and tetraploid Tartary buckwheat.Integrated metabolomics and transcriptome analysis revealed that chromosome doubling up-regulated the expression of upstream genes in the flavonoid biosynthesis pathway to promote the accumulation of flavonoids.The present results contribute to elucidation of the molecular mechanism of phenotypic variation associated with polyploidy in Tartary buckwheat.The findings provide a reference for further studies on phenotypic traits in polyploid Tartary buckwheat,the cloning of crucial regulatory genes,and utilization of genetic engineering technologies in the breeding of Tartary buckwheat.

Linear Arboricity of NIC-Planar Graphs

A graph is NIC-planar if it admits a drawing in the plane with at most one crossing per edge and such that two pairs of crossing edges share at most one common end vertex. It is proved that every NIC-planar graph with minimum degree at least 2(resp. 3) contains either an edge with degree sum at most 23(resp. 17) or a 2-alternating cycle(resp. 3-alternating quadrilateral). By applying those structural theorems, we confirm the Linear Arboricity Conjecture for NIC-planar graphs with maximum degree at least 14 and determine the linear arboricity of NIC-planar graphs with maximum degree at least 21.

Equitable Vertex Arboricity Conjecture Holds for Graphs with Low Degeneracy

The equitable tree-coloring can formulate a structure decomposition problem on the communication network with some security considerations.Namely,an equitable tree-Zc-coloring of a graph is a vertex coloring using k distinct colors such that every color class induces a forest and the sizes of any two color classes differ by at most one.In this paper,we show some theoretical results on the equitable tree-coloring of graphs by proving that every d-degenerate graph with maximum degree at most Δ is equitably tree-fc-colorable for every integer k≥(Δ+1)/2 provided that Δ≥9.818d,confirming the equitable vertex arboricity conjecture for graphs with low degeneracy.