Bayer AG.

Abstract:The gene encoding the MYB (v-myb avian myeloblastosis vira l oncogene homolog) transcription factor CmMYB19 was isolated from chrysanthemum. It encodes a 200 amino acid protein and belongs to the R2R3-MYB subfamily. CmMYB19 was not transcriptionally activated in yeast, while a transient expression experiment conducted in onion epidermal cells suggested that the CmMYB19 product localized to the nucleus. CmMYB19 transcription was induced by aphid (Macrosiphoniella sanborni) infestation, and the abundance of transcript was higher in the leaf and stem than in the root. The over-expression of CmMYB19 restricted the multiplication of the aphids. A comparison of transcript abundance of the major genes involved in lignin synthesis showed that CmPAL1 (phenylalanine ammonia lyase 1), CmC4H (cinnamate4 hydroxylase), Cm4CL1 (4-hydroxy cinnamoyl CoA ligase 1), CmHCT (hydroxycinnamoyl CoA-shikimate/quinate hydroxycinnamoyl transferase), CmC3H1 (coumarate3 hydroxylase1), CmCCoAOMT1 (caffeoyl CoA O-methyltransferase 1) and CmCCR1 (cinnamyl CoA reductase1) were all upregulated, in agreement with an increase in lignin content in CmMYB19 over-expressing plants. Collectively, the over-expression of CmMYB19 restricted the multiplication of the aphids on the host, mediated by an enhanced accumulation of lignin.

Background. Zinc plays a role in mitophagy and protects cardiomyocytes from ischemia/reperfusion injury. This study is aimed at investigating whether SUMOylation of Drp1 is involved in the protection of zinc ion on cardiac I/R injury. Methods. Mouse hearts were subjected to 30 minutes of regional ischemia followed by 2 hours of reperfusion (ischemia/reoxygenation (I/R)). Infarct size and apoptosis were assessed. HL-1 cells were subjected to 24 hours of hypoxia and 6 hours of reoxygenation (hypoxia/reoxygenation (H/R)). Zinc was given 5 min before reperfusion for 30 min. SENP2 overexpression plasmid (Flag-SENP2), Drp1 mutation plasmid (Myc-Drp1 4KR), and SUMO1 siRNA were transfected into HL-1 cells for 48 h before hypoxia. Effects of zinc on SUMO family members were analyzed by Western blotting. SUMOylation of Drp1, apoptosis and the collapse of mitochondrial membrane potential (ΔΨm), and mitophagy were evaluated. Results. Compared with the control, SUMO1 modification level of proteins in the H/R decreased, while this effect was reversed by zinc. In the setting of H/R, zinc attenuated myocardial apoptosis, which was reversed by SUMO1 siRNA. Similar effects were observed in SUMO1 KO mice exposed to H/R. In addition, the dynamin-related protein 1 (Drp1) is a target protein of SUMO1. The SUMOylation of Drp1 induced by zinc regulated mitophagy and contributed to the protective effect of zinc on H/R injury. Conclusions. SUMOylation of Drp1 played an essential role in zinc-induced cardio protection against I/R injury. Our findings provide a promising therapeutic approach for acute myocardial I/R injury.

MYB transcription factors are widely involved in the development of and physiological processes in plants. Here, we isolated the chrysanthemum R2R3-MYB family transcription factor CmMYB15, a homologous gene of AtMYB15. It was demonstrated that CmMYB15 expression was induced by aphids and that CmMYB15 could bind to AC elements, which usually exist in the promoter of lignin biosynthesis genes. Overexpression of CmMYB15 in chrysanthemum enhanced the resistance of aphids. Additionally, the content of lignin and the expression of several lignin biosynthesis genes increased. In summary, the results indicate that CmMYB15 regulates lignin biosynthesis genes that enhance the resistance of chrysanthemum to aphids.

MicroRNAs (miRNAs) are important regulators of gene expression, affecting many biological processes. As yet, their roles in the response of chrysanthemum to aphid feeding have not been explored. Here, the identity and abundance of miRNAs induced by aphid infestation have been obtained using high-throughput Illumina sequencing platform. Three leaf small RNA libraries were generated, one from plants infested with the aphid Macrosiphoniella sanbourni (library A), one from plants with mock puncture treatment (library M), and the third from untreated control plants (library CK). A total of 7,944,797, 7,605,251 and 9,244,002 clean unique reads, ranging from 18 to 30 nucleotides (nt) in length, were obtained from library CK, A and M, respectively. As a result, 303 conserved miRNAs belonging to 276 miRNAs families and 234 potential novel miRNAs were detected in chrysanthemum leaf, out of which 80, 100 and 79 significantly differentially expressed miRNAs were identified in the comparison of CK-VS-A, CK-VS-M and M-VS-A, respectively. Several of the differentially abundant miRNAs (in particular miR159a, miR160a, miR393a) may be associated with the plant's response to aphid infestation.