Wild oat ( Avena fatua L.) is a common and problematic weed in wheat fields in China. In recent years, farmers found it increasingly difficult to control A. fatua using acetyl-CoA carboxylase (ACCase)-inhibiting herbicides. The purpose of this study was to identify the molecular basis of clodinafop-propargyl resistance in A. fatua . In comparison to the S1496 population, whole dose response studies revealed that the R1623 and R1625 populations were 71.71- and 67.76-fold resistant to clodinafop-propargyl, respectively. The two resistant A. fatua populations displayed high resistance to fenoxaprop-p-ethyl (APP) and low resistance to clethodim (CHD) and pinoxaden (PPZ), but they were still sensitive to the ALS inhibitors mesosulfuron-methyl and pyroxsulam. An Ile-2041-Asn mutation was identified in both resistant individual plants. The copy number and relative expression of the ACCase gene in the resistant population were not significantly different from those in the S1496 population. Under the application of 2160 g ai ha −1 of clodinafop-propargyl, the fresh weight of the R1623 population was reduced to 74.9%; however, pretreatment with the application of the cytochrome P450 inhibitor malathion and the GST inhibitor NBD-Cl reduced the fresh weight to 50.91% and 47.16%, respectively, which proved the presence of metabolic resistance. This is the first report of an Ile-2041-Asn mutation and probable metabolic resistance in A. fatua , resulting in resistance to clodinafop-propargyl.
The evaluation of herbicidal activity and the isolation of plant allelopathic substances can lead to the discovery of new herbicide. This study has confirmed that the ethanol extract of S. mukorossi leaves was inhibitory to growth of Avena fatua L. and Amaranthus retroflexus L. both in petri dish experiment and pot culture assay, with the fresh weight inhibition varied between 47.60% and 62.05% at a concentration of 40 g/L of the leaf extract, being comparable to that of a commercialized natural product herbicide pelargonic acid at a concentration of 4 g/L. Five herbicidal compounds, oleanolic acid (1) , lupeol (2) , d-pinitol (3) , hexadecanoic acid (4) and octadecanoic acid (5) were isolated from the most active fraction, petroleum ether extract. D-pinitol (3) showed the highest growth inhibitory activity against both the shoot and root of A. fatua , with the half maximal inhibitory concentration (IC 50 ) values of 53.61 and 56.43 μg/mL, respectively. Furthermore, oleanolic acid (1) and d-pinitol (3) also inhibited the growth of A. retroflexus with the IC 50 value of 56.05 and 61.89 μg/mL against shoot growth, and 58.07 and 66.70 μg/mL against root growth, respectively. Thus, oleanolic acid (1) and d-pinitol (3) are the main phytotoxin constituents of S. mukorossi , and these compounds have the potential for further development as a botanical herbicide.
危险品化学品经营许可证（带存储）