Anthocyanins from Malus spp. inhibit the activity of Gymnosporangium yamadae by downregulating the expression of WSC, RLM1, and PMA1.

Malus plants are frequently devastated by the apple rust caused by Gymnosporangium yamadae Miyabe. When rust occurs, most Malus spp. and cultivars produce yellow spots, which are more severe, whereas a few cultivars accumulate anthocyanins around rust spots, forming red spots that inhibit the expansion of the affected area and might confer rust resistance. Inoculation experiments showed that Malus spp. with red spots had a significantly lower rust severity. Compared with M. micromalus, M. 'Profusion', with red spots, accumulated more anthocyanins. Anthocyanins exhibited concentration-dependent antifungal activity against G. yamadae by inhibiting teliospores germination. Morphological observations and the leakage of teliospores intracellular contents evidenced that anthocyanins destroyed cell integrity. Transcriptome data of anthocyanins-treated teliospores showed that differentially expressed genes were enriched in cell wall and membrane metabolism-related pathways. Obvious cell atrophy in periodical cells and aeciospores was observed at the rust spots of M. 'Profusion'. Moreover, WSC, RLM1, and PMA1 in the cell wall and membrane metabolic pathways were progressively downregulated with increasing anthocyanins content, both in the in vitro treatment and in Malus spp. Our results suggest that anthocyanins play an anti-rust role by downregulating the expression of WSC, RLM1, and PMA1 to destroy the cell integrity of G. yamadae.

MrMYB44-Like Negatively Regulates Anthocyanin Biosynthesis and Causes Spring Leaf Color of Malus 'Radiant' to Fade From Red to Green.

The "Spring-red-leaf" crabapple cultivar has young red leaves and mature green leaves. However, the mechanism of anthocyanin biosynthesis in crabapple leaves in spring remains unknown. In this study, Illumina RNA sequencing (RNA-Seq) was performed on Malus 'Radiant' leaf tissues in different stages of development. Twenty-two genes in the anthocyanin biosynthesis pathway and 44 MYB transcription factors (TFs) were significantly enriched among differentially expressed genes (DEGs). Three R2R3-MYB TFs in subgroup 22 of the MYB TF family, MrMYB44-like1, MrMYB44-like2, and MrMYB44-like3, were highly expressed in green leaves according to RNA-Seq and quantitative real-time quantitative PCR results. Their expression levels were negatively correlated with anthocyanin content. In transient assays, overexpression of MrMYB44-like1, MrMYB44-like2, or MrMYB44-like3 inhibited anthocyanin accumulation and reduced pigment in leaf disks of M. 'Radiant' and fruit peels of M. domestica 'Fuji.' When the conserved region of the three MrMYB44-likes was silenced, the anthocyanin biosynthesis pathway was activated and pigments increased in both tissues. Moreover, bimolecular fluorescence complementation assays showed MrMYB44-likes interacted with MrWRKY6 to form protein complexes that regulated anthocyanin biosynthesis.

How the Color Fades From Malus halliana Flowers: Transcriptome Sequencing and DNA Methylation Analysis.

The flower color of many horticultural plants fades from red to white during the development stages, affecting ornamental value. We selected Malus halliana, a popular ornamental species, and analyzed the mechanisms of flower color fading using RNA sequencing. Forty-seven genes related to anthocyanin biosynthesis and two genes related to anthocyanin transport were identified; the expression of most of these genes declined dramatically with flower color fading, consistent with the change in the anthocyanin content. A number of transcription factors that might participate in anthocyanin biosynthesis were selected and analyzed. A phylogenetic tree was used to identify the key transcription factor. Using this approach, we identified MhMYB10 as directly regulating anthocyanin biosynthesis. MhMYB10 expression was strongly downregulated during flower development and was significantly positively related to the expression of anthocyanin biosynthetic genes and anthocyanin content in diverse varieties of Malus. To analyze the methylation level during flower development, the MhMYB10 promoter sequence was divided into 12 regions. The methylation levels of the R2 and R8 increased significantly as flower color faded and were inversely related to MhMYB10 expression and anthocyanin content. Therefore, we deduce that the increasing methylation activities of these two regions repressed MhMYB10 expression.

[Analysis of flavonoids and antitumor activity of transgenic Saussurea involucrate].

The aim of this paper was to investigate the flavonoids of callus of transgenic and non-transgenic Saussurea involucrate and its antitumor activity on the esophageal cancer CaEs-17 cells. The species and content of mono-phenols were detected by high performance liquid chromatography. The growth of human esophageal cancer CaEs-17 cells was detected using CCK-8 assay, apoptosis morphology observation and flow cytometry. Expression of related apoptotic genes Bax and Bcl-2 were determined by qPCR. The results showed that the content of total flavonoids in the transgenic callus was 2.72 times that of the non-transgenic callus. The cyanidin-galactoside was detected in the transgenic callus, but not in the non-transgenic callus. The inhibitory effect of the extracts from the transgenic callus on CaEs-17 cells was more significant than that of the non-transgenic callus, and the IC50 value had a decreased of 26.4%. Flow cytometry analysis results showed that the apoptosis induction effect of the extracts from the transgenic callus on CaEs-17 cells was significantly better than that of the non-transgenic callus. Fluorescence quantitative PCR analysis results showed that the extracts from the transgenic callus could up-regulate the expression of proapoptotic gene Bax and down-regulate the expression of apoptotic gene Bcl-2, and the regulation effect of the transgenic callus was more significant. Therefore, compared with the non-transgenic callus, the antitumor activity of the extracts from the callus of transgenic S. involucrate on the esophageal cancer CaEs-17 cells was significantly increased, which was closely related to the accumulation of cyanidin-galactoside and its metabolism-related flavonoid compounds in the transgenic callus.

[Genetic diversity and genetic differentiation of Rhododendron concinnum wild populations in Qinling Mountains of Northwest China: an AFLP analysis].

By using amplified fragment length polymorphism (AFLP) technique, an investigation was made on the genetic diversity and genetic differentiation of seven wild populations of Rhododendron concinnum in Qinling Mountains of Northwest China. A total of 182 amplification products were generated from three AFLP selective primer combinations, of which, 151 were polymorphic. The percentage of polymorphism was 83.1%. The change trends showed by the percentage of polymorphic loci (PPL), Nei's gene diversity (h), and Shannon's information index (I) were uniform, and the order of the populations was Meixian > Zhashui > Zhen' an > Huxian > Ningqiang > Nanzheng > Zhouzhi. The POPGENE analysis showed that the R. concinnum had higher genetic diversity at both species level (PPL = 91.22%, I = 0.7217, h = 0.5095) and population level (PPL = 77.56%, I = 0.6409, h = 0.4725). The coefficient of gene differentiation among the populations (Gst) was 0.0726, indicating that 92.74% of genetic variation occurred within the populations. The analysis of molecular variance (AMOVA) showed that 85.3% of the genetic variation was within the populations, and 14.7% of it was among the populations. The unweighted pair group method with arithmeticmean (UPGMA) indicated that there was no significant correlation between the genetic distance and the geographic distance among the R. concinnum populations. The conservation strategies for R. concinnum germplasm resources were put forward.

Regio- and stereo-selective synthesis of aryl 2-deoxy-C-glycopyranosides by palladium-catalyzed Heck coupling reactions of glycals and aryl iodides.

The Heck coupling of aryl iodides with pyranoid glycals using a catalytic amount of Pd(OAc)(2) to form pyranoid aryl C-glycosides has been achieved. The reaction takes place smoothly in the presence of Ag(2)CO(3) and Cu(OAc)(2) (or DMSO) in acetonitrile. This arylation process, which occurs in a highly regio- and stereo-selective manner, provides a simple, mild, and efficient approach to the synthesis of aryl 2-deoxy-C-glycopyranosides.