Coumarins are the largest group of 1-benzopyran derivatives found in plants. The initial member of this group of compounds, coumarin (2H-1-benzopyran-2-one), a fragrant colorless compound, was first isolated from the Tonka bean (Dipteryx odorata, family Fabaceae) in 1820. The name coumarin comes from a French term for the tonka bean, coumarou. Since the discovery of coumarin, several of its derivatives, with umbelliferone (7-hydroxycoumarin) being the most common one, have been reported from various natural sources. The families Apiaceae, Asteraceae, and Rutaceae are the three major plant sources of coumarins.

Progress in the Chemistry of Naturally Occurring Coumarins.

Herbicide safeners enhance herbicide detoxification in crops without affecting target weed sensitivity. To enhance crop tolerance to the toxicity-related stress caused by the herbicide acetochlor (...

Design, Synthesis, and Bioevaluation of Substituted Phenyl Isoxazole Analogues as Herbicide Safeners.

Echinochloa crusgalli (L.) Beauv. (barnyard grass) is considered a noxious weed worldwide, and is the most pernicious weed decreasing rice yields in China. Recently, E. crusgalli has evolved quinclorac resistance, making it among the most serious herbicide resistant weeds in China. The present study explored differences in germination and growth between quinclorac-resistant and -susceptible E. crusgalli collected in Hunan Province. The order of the seven E. crusgalli biotypes assessed, from high to low quinclorac-resistance, was: quinclorac-resistant, Chunhua, Hanshou, Shimen, Hekou, Dingcheng, and quinclorac-susceptible. With an increased in the level of quinclorac-resistance, the germination rate, length of young shoots and roots, and fresh weight of E. crusgalli were all decreased compared with that in more susceptible biotypes. However, there were no significant differences between quinclorac-resistant and susceptible E. crusgalli biotypes without polyethylene glycol 6000 treatment. Drought had a more obvious effect on glutathione S-transferases (GST) activity, determined by spectrophotometric method, in quinclorac-resistant E. crusgalli. Higher resistance level biotypes showed greater activity, and when treated with polyethylene glycol 6000 for 3 days, all E. crusgalli biotypes showed the highest GST activity. This study demonstrated that as the level of quinclorac-resistance increased, the rate of seed germination decreased, while the growth of young buds, young roots, and fresh weight decreased. Increased quinclorac-resistance may be related to the increased metabolic activity of GST in E. crusgalli.

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Effects of drought-stress on seed germination and growth physiology of quinclorac-resistant Echinochloa crusgalli

Fenclorim (Fen) can effectively protect rice from pretilachlor (Pre) injury, but its effects on rice have not been formally evaluated; thus, the Fen mode of action for alleviating the phytotoxicity caused by Pre in rice is not clear. This study aimed to examine the biochemical and physiological effects of Fen on rice and to determine the changes induced by Fen at the transcriptome level. The chlorophyll content of rice plants was significantly affected by Pre but not by Fen. The activity of oxidative stress enzymes showed that Fen did not elicit any changes in oxidative stress; however, it reduced lipid peroxidation and oxidative damage induced by Pre. Fen did not affect the uptake of Pre but did affect its persistence in rice. In a transcriptome experiment, Fen upregulated genes in a detoxification pathway. Overall, 25 genes related to detoxification were identified, including P450, GST, and GT. Moreover, qRT-PCR analysis showed that four P450 genes, CYP71Y83, CYP71K14, CYP734A2 and CYP71D55, and two GST genes, GSTU16 and GSTF5, were upregulated by Fen and/or Pre. Our work indicates that Fen acts in antioxidative defense in addition to enhancing the metabolism of herbicides in rice.

/pdf/effects-of-fenclorim-on-rice-physiology-gene-transcription-1lowagycg6.pdf

Effects of fenclorim on rice physiology, gene transcription and pretilachlor detoxification ability

BACKGROUND Asia minor bluegrass (Polypogon fugax) is one of the main weeds invading Chinese canola fields. The P. fugax resistant population SC-R, which survived quizalofop-p-ethyl at the field-recommended rate (67.5 g ha-1 ), was collected from a canola field in Qingsheng County in China. The present study aimed to (1) characterize the SC-R resistance pattern to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides, and (2) investigate the mechanism of quizalofop-p-ethyl resistance in this population. RESULTS Dose-response studies showed that resistance to quizalofop-p-ethyl and haloxyfop occurred in the SC-R population. Four transcripts/genes encoding the plastidic ACCase carboxyl-transferase domain were isolated from the P. fugax plants. No mutations in the four ACCase genes were detected in the SC-R population compared to the SC-S population. Pre-treatment with the known glutathione S-transferase (GST) inhibitor 4-chloro-7-nitrobenzoxadiazole (NBDCl), reversed resistance to quizalofop-p-ethyl and partially reversed resistance to haloxyfop-R-methyl in the resistant population (SC-R). However, the cytochrome P450 inhibitor malathion did not reverse the resistance. There was no difference in basal GST activity (using CDNB as a substrate), but there was higher inducible GST activity in SC-R relative to SC-S. Two GST genes, GST2c and GSTL3, were constitutively overexpressed in the resistant SC-R population. CONCLUSION This study confirmed that resistance to quizalofop-p-ethyl in the resistant P. fugax population is likely nontarget-site based involving GST, and this resistance mechanism also partially confers haloxyfop-R-methyl resistance. © 2020 Society of Chemical Industry.

Quizalofop‐p‐ethyl resistance in Polypogon fugax involves glutathione S‐transferases

Asia minor bluegrass (AmB) is a major weed impacting rapeseed production in Dongting Lake District, China. Growth chamber experiments were conducted to determine the influence of environmental factors on germination and emergence of AmB. The optimum constant temperature for germination was around 20 C. Seeds showed germination percentages above 60% under 22/15 and 24/19 C day/night temperature regimes. Seeds could germinate in the dark, but light exposure significantly enhanced the germination percentage. More than 50% of seeds germinated over a pH range between 4 and 10. Seeds were highly sensitive to osmotic stress, and germination was completely inhibited at an osmotic potential of −0.4 MPa, indicating that it was favored by a moist environment. Increasing salinity reduced germination of AmB seeds from 58% at 0 mM to 13% at 80 mM NaCl. The highest seedling emergence (62%) was observed when seeds were placed on the soil surface, and no seedlings emerged from seeds placed at a depth of 5 cm. This work sh...

https://bioone.org/journals/weed-technology/volume-30/issue-2/WT-D-15-00043/Influence-of-Environmental-Factors-on-Seed-Germination-and-Emergence-of/10.1614/WT-D-15-00043.pdf

Influence of Environmental Factors on Seed Germination and Emergence of Asia Minor Bluegrass (Polypogon fugax)

Rhizoma et Radix Notopterygii is often used as a traditional medicine in China. In our recent work, we found that the ethanol crude extract of Rhizoma et Radix Notopterygii could reduce phytotoxicity of acetochlor on rice. The crude extract of Rhizoma et Radix Notopterygii was isolated and purified by activity-guided fractionation. Two coumarins, isopimpinellin and 5-methoxypsoralen (5-MOP) were identified, and their bioactivity was tested in a growth chamber. The results showed that the two coumarins increased herbicide tolerance of rice shoots, and 5-MOP demonstrated better protection than isopimpinellin. The treatment of 5-MOP at 50 g ai ha−1 recovered the shoot height of rice from 42.6% (treated with acetochlor only) to 81.6% of the control treated without acetochlor, whereas the phytocidal activity of acetochlor on barnyardgrass was not impaired by 5-MOP. Further study suggested that 5-MOP increases herbicide tolerance of rice by enhancing the glutathione S-transferase level of activity in r...

Two Coumarins with Safener Activity from Rhizoma et Radix Notopterygii

The invention relates to a method for quickly degrading organophosphorus pesticide in fruits and vegetables with nanometer degradation agent, which can realize quick degrading of organophosphorus pesticide under natural light. The usage amount of nanometer degradation agent for organophosphorus pesticide is that the effective component is 37.5 to 150 g/hm , after being mixed with organophosphorus pesticide, the nanometer degradation agent is mixed with 750 L/hm of water to be sprayed on vegetables and fruits uniformly and constantly in the peak seasons of pests, or in 12 to 24 hours before fruits and vegetables are harvested, the novel nanometer degradation agent for organophosphorus pesticide, which has the effective component of 37.5 to 150 g/hm , is directly mixed with 750 L/hm of water to be sprayed on vegetables and fruits uniformly and constantly, or after fruits and vegetables are harvested, the novel nanometer degradation agent for organophosphorus pesticide is directly mixed with water to be diluted to be 20 to 200 mg/L, and vegetables and fruits are soaked for 15 to 60 min, so that an ideal degradation effect can be achieved.

Method for degrading organophosphorus pesticide in fruits and vegetables with nanometer degradation agent

The invention discloses a method for breaking the dormancy of digitaria sanguinalis seeds. The method comprises the following steps: (1) selecting seeds, namely screening out the seeds which are full in grains and fully mature from collected digitaria sanguinalis seeds which do not go through the period of the dormancy; (2) removing seed shells, namely kneading the screened seeds into a nylon gauze bag for 2-4 minutes by hands; (3) soaking the seeds in hot water, namely soaking the shelled mature seeds in distilled water at 55-65 DEG C for 15-20 minutes; (4) soaking the seeds with hormones, namely soaking with a mixed liquid of gibberellins and 6-benzylamino adenine for 18-30 hours; (5) washing the seeds, namely washing the seeds processed in the step (4) with the distilled water for 2-4 minutes; and (6) accelerating germination, namely accelerating the germination of the seeds processed in the step (5) at 30-35 DEG C. A research proves that the germination rate of the digitaria sanguinalis seeds after being germinated for 8 days by adopting the method disclosed by the invention can reach about 80%.

Xiaomao Zhou

Papers

Influence of Environmental Factors on Seed Germination and Emergence of Asia Minor Bluegrass (Polypogon fugax)

Two Coumarins with Safener Activity from Rhizoma et Radix Notopterygii

Method for degrading organophosphorus pesticide in fruits and vegetables with nanometer degradation agent

Method for breaking dormancy of digitaria sanguinalis seeds