我国水稻田稗属杂草种类分布特点: 以9个省级行政区73个样点调查数据为例

除草剂二氯喹啉酸长期使用已导致部分稗草出现高水平抗药性，氨基酸在植物代谢中发挥着重要作用。本研究以抗二氯喹啉酸的孔雀稗Echinochloa crus-pavonis为试材，研究了在500 μmol/L二氯喹啉酸胁迫下，外源添加200、400、600和800 μmol/L系列浓度的L-甲硫氨酸和L-半胱氨酸的等摩尔浓度混合液处理，对抗性型孔雀稗生长、抗氧化酶和解毒酶活性以及乙烯生物合成及氰化物解毒相关基因表达的影响。结果表明：在没有除草剂胁迫时，上述氨基酸混合液处理对抗性孔雀稗生长无显著影响，对其超氧化物歧化酶 (SOD) 和过氧化氢酶 (CAT) 活性也没有影响，仅600和800 μmol/L氨基酸混合液处理可显著抑制多酚氧化酶 (PPO) 活性；而在500 μmol/L的二氯喹啉酸胁迫下，氨基酸混合液预处理对抗性稗草的生长存在低浓度促进高浓度抑制现象，同时，随着氨基酸混合液浓度升高，稗草抗氧化酶 (SOD、CAT、PPO) 及解毒酶谷胱甘肽S-转移酶 (GSTs) 活性整体表现为逐渐降低趋势，而过氧化物酶(POD)活性则逐渐升高。此外，外源添加L-甲硫氨酸和L-半胱氨酸混合液处理显著激活了乙烯信号途径，乙烯信号途径1-氨基环丙烷基-1-羧酸 (ACC) 合成酶基因、ACC氧化酶基因以及与氰化物解毒相关的β-氰丙氨酸合成酶基因EC_CAS均随着氨基酸混合液浓度的升高而上调表达，其中600和800 μmol/L混合液预处理强烈诱导了所有5个测试基因的表达水平。本研究发现，外源施加L-甲硫氨酸和L-半胱氨酸混合液可通过影响植物乙烯信号途径而调控稗草对除草剂二氯喹啉酸的抗性，对降低稻田中除草剂的施用量以及减缓稗草对二氯喹啉酸抗性的产生和发展均有重要意义。

Distribution characteristics of Echinocloa species in rice fields in China: a case survey on 73 sites from nine provincial administrative regions

Long-term application of the herbicide quinclorac has led to high levels of resistance in barnyard grass (Echinochloa spp.). Amino acids play an important role in plant metabolic processes. By use of quinclorac-resistant barnyard grass E. crus-pavonis, this study examined the effects of external application of an equimolar mixture of L-methionine and L-cysteine (concentrations: 200, 400, 600, 800 μmol/L) on the growth, and antioxidant enzyme activity, and gene expression related to ethylene biosynthesis and cyanide detoxification in the plant exposed to 500 μmol/L quinclorac. In the absence of quinclorac, the treatment with mixtures of the two amino acids had no significant effect on growth, and did not show any effect on SOD and CAT enzyme activities either. The treatment of 600 and 800 μmol/L mixture significantly inhibited PPO enzyme activity. However, after exposure of the plants to quinclorac, the mixture stimulated the growth at lower concentration but inhibited the growth at higher concentration. Meanwhile, the activity of antioxidant enzymes SOD, CAT, PPO and detoxifying enzyme GSTs increased first and then decreased, while the activity of POD increased gradually with the concentration of L-methionine and L-cysteine elevated. More importantly, pretreatment of the two amino acid mixtures significantly activated the ethylene signaling pathway, and the expression of the ACC synthase gene, ACC oxidase gene, and β-cyanalanine synthase gene EC_CAS related to cyanide detoxification were increased. The mixture at 600 and 800 μmol/L strongly induced the expression of all five tested genes. This study revealed that exogenous application of L-methionine and L-cysteine regulates the resistance of barnyard grass to herbicide quinclorac by affecting the ethylene signaling pathway, which is of great significance in reducing the application amount of herbicides in rice fields and slowing down the resistance of barnyard grass to quinclorac.