Background: Ziziphora bungeana Juz. is a folk medicine from the Xinjiang Uygur Autonomous Region. The herb or the aerial parts of it have been used to medicinally treat cardiovascular diseases. Flavonoids are the main pharmacologically active ingredients in Z. bungeana. Identification of the tissue-specific distribution of flavonoids in Z. bungeana is crucial for effective and sustainable medicinal use of the plant. Furthermore, understanding of the biosynthesis pathways of these flavonoids in Z. bungeana is of great biological significance. Methods: The flavonoids from different tissues of Z. bungeana were identified using liquid chromatography-tandem mass spectrometry (LC–MS/MS). The full-length transcriptome of Z. bungeana was determined using a strategy based on a combination of Illumina and PacBio sequencing techniques. The functions of differentially expressed unigenes were predicted using bioinformatics methods and further investigated by real-time quantitative PCR and phylogenetic relationship analysis. Results: Among the 12 major flavonoid components identified from Z. bungeana extracts, linarin was the most abundant component. Nine flavonoids were identified as characteristic components of specific tissues. Transcriptome profiling and bioinformatic analysis revealed that 18 genes were putatively involved in flavonoid biosynthesis. The gene expression and phylogenetic analysis results indicated that ZbPALs, Zb4CL3, ZbCHS1, and ZbCHI1 may be involved in the biosynthesis of the main flavonoid intermediate. ZbFNSII, ZbANS, and ZbFLS may be involved in the biosynthesis of flavones, anthocyanins, and flavonols, respectively. A map of the biosynthesis pathways of the 12 major flavonoids in Z. bungeana is proposed. Conclusions: The chemical constituent analysis revealed the compositions of 9 characteristic flavonoids in different tissues of Z. bungeana. Linarin can be hydrolysed into acacetin to exert a pharmaceutical role. Apigenin-7-O-rutinoside is hypothesised to be the precursor of linarin in Z. bungeana. There was greater content of linarin in the aerial parts of the plant than in the whole herb, which provides a theoretical basis for using the aerial parts of Z. bungeana for medicine. These results provide a valuable reference for further research on the flavonoid biosynthesis pathways of Z. bungeana and will be significant for the effective utilisation and ecological protection of Z. bungeana.

Zucchini yellow mosaic virus (ZYMV) causes one of the most destructive diseases of cucurbits worldwide. Although the virus has been present in China for more than 25 years, there is little information about biological and molecular traits of ZYMV isolates from China. This study aimed to characterize 26 ZYMV isolates from Xinjiang, China based on pathotypes, molecular variability and host range. Phylogenetic analysis of the complete sequences of the coat protein gene revealed three distinct groups (A, B and C), with four subgroups in A (I–IV). All isolates from Xinjiang were placed in group C and subgroups A–I and A–II. To test for differences in host range among different phylogenetic groups from Xinjiang, 13 isolates were mechanically inoculated onto 14 plant species in five families and their pathotypes were also identified based on the reaction of a resistant melon accession PI414723. Overall, the results showed that there were no correlations of host responses to inoculation with ZYMV isolates from different phylogenetic groups. However, on Cucurbita pepo, differences in host responses to inoculation with the ZYMV isolates from different phylogenetic groups were observed. Although the host range of the 13 isolates tested was similar, their biological properties on different hosts were slightly different from the ZYMV isolates characterized in other countries. The results of the pathotype test showed that the 13 ZYMV isolates were classified as pathotype 0. The information obtained is important in breeding for resistant varieties.

Genetic relationships and classifications of a set of melon accessions were analyzed to provide the experimental support for utilizing effectively genetic materials for breeding. Sequence-related amplified polymorphism technique was adopted to analyze 61 melon accessions. Sixteen primer combinations with clear band pattern and polymorphism were selected from over 42 primer combinations. Four hundred and fifty-two loci were detected by 16 pairs of SRAP primers. Among them, 265 were polymorphic, the polymorphic rate was 58.63%, and 28.56 loci and 16.56 polymorphic loci were amplified by each pairs of primers on average. The genetic similarity coefficient of the 61 accessions ranged from 0.48 to 0.93, with an average of 0.73. These results suggested that there was rich genetic diversity among the melon accessions tested. The varieties examined were clustered into two groups,which were thick-skinned melon and thin-skinned melon. Five groups were clustered according to genetic similarity coefficient of 0.74. The Nei's gene diversity index and Shannon's Information index of melon were 0.2231 and 0.3422, respectively, in Xinjiang, the highest among all the ecological regions.