图1. 共生体系中NO的产生与降解示意图(改自Hichri et al., 2016a)
图中包含上下2部分, 分别对应植物和共生体NO的产生与降解。其中, 七角星图示代表氧化途径, 椭圆形图示代表还原途径。实线表示已有研究证实, 虚线表示还有待考证。ETC: 线粒体电子传递链; GSNOR: 亚硝基谷胱甘肽还原酶; Hmp: 黄素血红蛋白; Lb: 豆血红蛋白; NnrS: 含血红素和铜的膜蛋白; Nor: NO还原酶; NOS: NO合酶; ns-Hb: 非共生血红蛋白; NR: 硝酸还原酶; PAOX: 多胺氧化酶; sd-Hb: 单域血红蛋白; Tr-Hb: 截短血红蛋白; TrxR: 硫氧还蛋白还原酶; XOR: 黄嘌呤氧化还原酶

Figure 1. The schematic diagram of NO production and degradation in the symbiotic system (modified from Hichri et al., 2016a)
The figure contains the upper and lower parts, which correspond to the production and degradation of NO from plants and symbiotes, respectively. The seven horns star diagrams refer to the oxidation pathway and the oval diagrams refer to the reduction pathway. The lines indicate that studies have been confirmed, and the dashed lines indicate that it is yet to be studied. ETC: Mitochondrial electron transport chain; GSNOR: S-nitrosoglutathione reductase; Hmp: Flavin hemoglobin; Lb: Leghemoglobin; NnrS: Haem- and copper-con- taining membrane protein; Nor: NO reductase; NOS: NO synthase; ns-Hb: Nonsymbiotic hemoglobin; NR: Nitrate reductase; PAOX: Polyamine oxidase; sd-Hb: Single domain hemoglobin; Tr-Hb: Truncated hemoglobin; TrxR: Thioredoxin reduction enzymes; XOR: Xanthine oxidoreductase