Synthesis and Biological Activities of Myricetin Derivatives Containing Quinoxaline
CHEMICAL JOURNAL OF CHINESE UNIVERSITIES-CHINESE
Authors: Li Pu; Chen Ying; Xia Rongjiao; Guo Tao; Zhang Min; Jiang Shichun; Tang Xu; He Ming; Xue Wei
According to the active substructure combination theory, a series of novel myricetin derivatives containing quinoxaline moieties was synthesized by introducing the quinoxaline blocks into the structures of myricetins. The antibacterial activities of the target compounds were evaluated via turbidimeter test in vitro. The preliminary bioassay results indicated that all of the title compounds exhibited certain antibacterial activities in vitro against Xanthomonas axonopodis pv. Citri (X. citri) and Xanthomonas oryzae pv. Oryzae (X. oryzae) . The compounds were also tested to evaluate the half maximal effective concentration (EC50) of phytopathogenic bacteria. The results showed that all the X. citri ECof the target compounds were superior to those of the control drugs of bismerthiazol and thiodiazole copper(54. 85 and 61. 13 mu g/mL, respectively) . Compound 4o (EC50 = 11. 17 mu g/mL) exhibited the best activity. All of the X. oryzae EC50 of the target compounds were superior to the control drugs of bismerthiazol and thiodiazole copper (148. 20 and 175. 47 mu g/mL , respectively) . Compound 4f(EC50= 34. 49 mu g/mL) exhibited the best activity. The in vivo efficacies against tobacco mosaic virus (TMV) of the target compounds were tested through half-leaf method. The results of bioassay showed that the target compounds exhibited certain anti-TMV activities at the concentration of 500 mg/L.
Plant NLR immune receptor Tm-2(2) activation requires NB-ARC domain-mediated self-association of CC domain
Authors: Wang, Junzhu; Chen, Tianyuan; Han, Meng; Qian, Lichao; Li, Jinlin; Wu, Ming; Han, Ting; Cao, Jidong; Nagalakshmi, Ugrappa; Rathjen, John P.; Hong, Yiguo; Liu, Yule
The nucleotide-binding, leucine-rich repeat-containing (NLR) class of immune receptors of plants and animals recognize pathogen-encoded proteins and trigger host defenses. Although animal NLRs form oligomers upon pathogen recognition to activate downstream signaling, the mechanisms of plant NLR activation remain largely elusive. Tm-2(2) is a plasma membrane (PM)-localized coiled coil (CC)-type NLR and confers resistance to Tobacco mosaic virus (TMV) by recognizing its viral movement protein (MP). In this study, we found that Tm-2(2) self-associates upon recognition of MP. The CC domain of Tm-2(2) is the signaling domain and its function requires PM localization and self-association. The nucleotide-binding (NB-ARC) domain is important for Tm-2(2) self-interaction and regulates activation of the CC domain through its nucleotide-binding and self-association. (d)ATP binding may alter the NB-ARC conformation to release its suppression of Tm-2(2) CC domain-mediated cell death. Our findings provide the first example of signaling domain for PM-localized NLR and insight into PM-localized NLR activation. Author summary Nucleotide-binding, leucine-rich repeat proteins (NLR) can function as immune receptors of plants and animals and confer resistance against pathogens. However, despite their importance in immunity, the activation mechanism of PM-localized NLRs remains largely elusive. In this study, we demonstrate that CC domain is the signaling domain for inducing cell death for PM-localized NLR Tm-2(2). Further, we report that nucleotide-binding (NB-ARC) domain is important for Tm-2(2) self-association and regulates activation of CC domain through its nucleotide-binding and self-association. Our findings provide the first example of signaling domain for PM-localized NLR and insight into PM-localized NLR activation.