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1.
The rate of photosynthesis in intact leaves attached to plants of an atrazine-resistant cultivar of Brassica napus L. was compared with that in leaves of an atrazine-susceptible, rather isogenic cultivar, in a number of irradiance series. The resistant cultivar had been obtained from the susceptible cultivar by crossing the resistant biotype of Brassica campestris L. with the susceptible cultivar of B. napus, and using the fourth back-cross for comparison. At a natural CO2 concentration (360 cm3 m?3) the rate of photosynthesis of leaves of the atrazine-resistant cultivar was significantly (17–21%) less than that of leaves of the susceptible cultivar, over the whole range of irradiances up to 250 W m?2 At the enriched CO2 concentration of 1500 cm?3 m?3 this reduction in rate amounted to 9–12%.  相似文献   

2.
Triazine-resistant (R) biotypes of Amaranthus albus L. (tumble pigweed), A. blitoides S. Wats. (prostrate pigweed), A. hybridus L. (smooth pigweed), A. retroflexus (redroot pigweed), and Solanum nigrum L. (black nightshade) were found in Spain. The former two R biotypes were found in simazine-treated, non-tilled olive orchards, whereas the latter three came from atrazine-treated maize (Zea mays L.) crops. All R biotypes survived at rates up to 5.0 kg ha?1 of soil-incorporated atrazine or simazine, whereas their susceptible (S) or ‘wild type’ counterparts were completely controlled at levels of 0.25 kg ha?1 atrazine, in the case of A. hybridus, A. retroflexus and S. nigrum, and 2.5 kg ha?1 in the case of A. albus and A. blitoides. The higher tolerance to triazines of these latter S biotypes appears to be attributable to herbicide detoxification. Photosynthetic electron transport in R biotypes was little affected by atrazine and simazine, but was inhibited by diuron, as shown by fluorescence induction measurements in whole leaves. In Hill reaction assays, the R biotypes showed a high level of resistance to atrazine and simazine (resistance factors in the range 350–900), and very slight resistance to diuron (resistance factors in the range 1.1–1.6). It is concluded that all R biotypes have evolved a chloroplastic mode of resistance similar to that previously described for other triazine-resistant weed biotypes. Résistances aux triazines des biotypes de Solanum nigrum et 4 espèces d'Amaranthus trousiées en Espagne Des biotypes résistant aux triazines (R) d'Amaranthus albus L., d'A. blitoïdes S. Wats, d'A. hybrydus et d'A. retroflexus et de Solanum nigrum L. ont été trouvés en Espagne. Les 2 premiers biotypes (R) ont été trouvés dans des oliveraies non labourées traitées à la simazine, tandis que les 3 derniers viennent de cultures de maïs traitées à l'atrazine. Tout les biotypes R ont survécu à des doses jusqu'à 5 kg ha?1 d'atrazine ou de simazine incorporée au sol tandis que leurs équivalents sensibles (S) ou ‘types sauvages’étaient complètement détruits à des doses de 0,25 kg ha?1 d'atrazine dans le cas d'A. hybridus, A. retroflexus et S. nigrum et de 2,5 kg ha?1 dans le cas d'A. albus et A. blitoïdes. La tolérance plus élevée aux triazines de ces 2 derniers biotypes apparaît être attribuable à la détoxification de l'herbicide. Le transport des d'électrons photosynthétiques dans les biotypes R a été peu affecté par l'atrazine et la simazine mais a été inhibé par le diuron, comme l'ont montré des mesures d'induction de fluorescence dans des feuilles entières. Dans des essais de réaction de Hill, les biotypes R ont exprimé une haute résistance à l'atrazine et à la simazine (facteurs de résistance de 350 à 900) et une très faible résistance du diuron (facteurs de résistance de 1,1 à 1,6). Il est conclu que tous les biotypes R ont développé un mode de résistance chloroplastiques identique à celui déjà décrit par d'autres biotypes d'adventices résistant aux triazines. Triazinresistenz bei Biotypen von Solanum nigrum und vier Amaranthus-Arten in Spanien Triazinresistente Biotypen (R) von Amaranthus albus L. (Weißer Amarant), A. blitoides S. Watson (Westamerikanischer A.), A. hybridus L. (Grünähriger A.), A. retroflexus L. (Zurückgekrümmter A.) und Solanum nigrum L. (Schwarzer Nachtschatten) wurden in Spanien gefunden. Die ersten beiden R-Biotypen stammten aus Simazin-behandelten Olivengärten ohne Bodenbearbeitung, die drei anderen von Atrazin-behandeltem Mais (Zea mays L.). Alle R-Biotypen ertrugen biszu 5,0kg ha?1 Atrazin oder Simazin, in den Boden eingcarbeitet, während empfindliche (S) oder ‘wilde’ Pflanzen mit 0,25 kg ha?1 Atrazin (A. hybridus, A. retroflexus, S. nigrum) und 2,5 kg ha?1 (A. albus, A. blitoides) bekämpfbar waren. Die höhere Triazintoleranz der beiden letzten Arten ist wahrscheinlich, auf eine Herbizidde-toxifikation zurückzuführen. Der photosynthetische Elektronentransport in den R-Biotypen wurde durch Atrazin und Simazin nur wenig beeinflußt, durch Diuron jedoch unterbunden, wie durch Messungen der Fluoreszenzinduktion der ganzen Blätter gefunden wurde. Bei der Untersuchung der Hill-Reaktion wurde bei den R-Biotypen für Simazin und Atrazin Resistenzfaktoren zwischen 900 und 350 festgestellt, für Diuron aber nur kleine Faktoren (1,1 bis 1,6). Daraus wurde geschlossen, daß alle R-Biotypen eine chloroplastische Resistenz entwickelt haben, wie sie schon früher für andere Triazin-resistente Unkrautbiotypen beschrieben worden ist.  相似文献   

3.
A biotype of Sonchus oleraceus L. and two bio types of Sisymbrium orientate Torn., SSO 3 and NSO 1, are the first dicot weeds in Australia to develop resistance to ALS-inhibiting herbicides. The resistant biotypes had been exposed to va rying periods of selection with sulfonylurea her bicides. All three biotypes are resistant to a range of sulfonylurea and imidazolinone herbicides. The S. orientale biotypes are also resistant to the triazolopyrimidine herbicide, flumetsulam. LD50 ratios of resistant Sonchus oleraceus for sulfony lurea and imidazolinone herbicides are greater than 64-fold and 4.5-fold, respectively. GR50 ratios are greater than 9 for sulfonylureas and 7.4 for imazapyr. The LD50 ratios for both S. orien tale biotypes for chlorsulfuron, sulfometuron methyl, metsulfuron-methyl, flumetsulam and imazethapyr are greater than 110-, 15-, 7-, 24- and 29-fold, respectively. All resistant biotypes are susceptible to MCPA, diuron and diflufenican, herbicides which do not inhibit ALS.  相似文献   

4.
Leaf chlorophyll fluorescence (LCF) of atrazine-susceptible Sinapis arvensis L. (wild mustard) biotype was greatly increased (119–181%)and the Hill reaction activity of isolated chloroplasts was inhibited by 104 M of either atrazine, metribuzin or diuron. In contrast the LCF as well as photochemical activity of the chloroplasts of resistant biotype remained unaffected by 104 M atrazine. However, in response to 104 M metribuzin, LCF of the resistant biotype increased by 43% and Hill reaction activity of the chloroplasts was partially blocked. Complete inhibition of the Hill reaction and a 96% LCF increase in response to diuron indicated that the atrazine-resistant S. arvensis biotype had no tolerance to diuron. Similar chloroplast photoreaction responses were observed when the known atrazine-susceptible and resistant Brassica campestris L. (bird's rape) biotypes and B. napus L. cv. Laurentian (rutabaga) genotypes were subjected to the triazine and urea herbicides. These results indicate that resistance to atrazine, in the resistant S. arvensis biotype, is based in the chloroplasts and could involve a selective modification of the PS II complex with respect to the triazine herbicides. Résistance chloroplastique aux herbicides de la famille des triazines chez Sinapsis arvensis L. (moutarde des champs) Chez un biotype de Sinapis arvensis L. (Moutarde des champs) sensible à l'atrazinc. la fluorescence chlorphyllienne des feuilles était fortement augmentée (de 119 à 181%), et la réaction de Hill des chioroplastes isolés, fortement diminuée, par des traitements à l'atrazinc. la métribuzine ou le diuron 104 M. Par contre, ni la fluorescence chlorophyllienne ni la réaction de Hill n'étaient affectées par de l'atrazine 104 M chez un biotype résistant. Toutefois, en réponse à de la métribuzine 104 M, la fluorescence chlorophyllienne du biotype résistant était augmentée de 43%, et la réaction de Hill chez les chioroplastes était partiellement bloquée. L'inhibition complète de la réaction de Hill et une augmentation de 96% de la fluorescence chlorophyllienne après traitement au diuron indiquaient que le biotype de S. arvensis résistant à l'atrazine ne manifestait pas de tolérance à l'égard du diuron. Par comparaison, des réponses chloroplasliques similaires ont été obtenues lorsque des biotypes de Brassica campestris L. (navette des oiseaux) et des génotypes de B. napus L. cv Laurentian (rutabaga) sensibles ou résistants à l'atrazinc ont été traités par des herbicides de la famille des triazines et des urées substituées. Ces résultats montrent que la résistance à l'atrazine, chez le biotype S. arvensisétudié, est un caractère chloroplastique et implique probablement une modification sélective du complexe PS II à l'égard des triazines. Chlaraplastenresistenz gegen Triazinherbizide bei Sinapis arvensis L. (Ackersenf) Bei atrazinempfindlichen Biotypen von Sinapis arvensis L. wurde die Blattchlorophyll-Fluores-zenz (LCF) in isolierten Chloroplasten durch 104m Atrazin, Metribuzin oder Diuron stark gesteigert (119–181%), die Hillreaktion aber gehemmt. In resistenten Biotypen hingegen blieben LCF und die photochemische Aktivität durch 10?4m Atrazin unbeeinflusst. Resistente Biotypen reagierten auf 10?4m Metribuzin mit einer Erhöhung der LCF um 43% während die Hillreaktion in den Chloroplasten teilweise blockiert wurde. Eine komplette Hemmung der Hillreaktion und eine um 96% gesteigerte LCF durch Diuron weisen darauf hin, dass atrazinresistente Biotypen von S. arvensis gegenüber Diuron nicht resestent sind. Aehnliche Veränderungen der Photoreaktionen in Chloroplasten konnten beobachtet werden, wenn atrazinemp-findliche und -resistente Brassica campestris L., Biotypen (Ackerkohl) und B. napus L. cv. Laurentian, Genotypen (Kohlrübe) Triazin- und Harnstoffherbiziden exponiert wurden. Diese Ergebnisse weisen darauf hin, dass die Ursache der Unempfindlichkeit gegenüber Atrazin bei den resistenten S. arvensis-Biotypen in den Chloroplasten liegt und dass eine selektive Veränderung des PS II Komplexes in Bezug auf die Triazinherbizide eingeleitet werden kann.  相似文献   

5.
An acetolactate synthase (ALS)‐resistant Amaranthus retroflexus biotype was collected in a soyabean crop after repeated exposure to imazethapyr and thifensulfuron‐methyl in north‐eastern Italy. Studies were conducted to characterise the resistance status and determine alternative post‐emergence herbicides for controlling this biotype. Whole‐plant bioassay revealed that the GR50 values were 1898‐ and 293‐fold higher than those observed for the biotype susceptible to imazethapyr and imazamox respectively. The biotype also displayed high cross‐resistance to sulfonylureas. Molecular analysis demonstrated that a single nucleotide substitution had occurred in domain B (TGG to TTG at position 574), conferring a change from the amino acid tryptophan to leucine in the resistant biotype. However, herbicides with other modes of action (PSII, 4‐HPPD and PPO inhibitors) provided excellent control. The GR50 ratios for metribuzin, terbuthylazine and mesotrione were close to 1 and treatments with fomesafen gave 100% control of both susceptible and resistant biotypes at the recommended field dose. This study documents the first case of an imidazolinone and ALS‐resistant biotype in European crops and identifies the post‐emergence herbicide options available for managing this troublesome weed in soyabean crops. Alternative management strategies are also discussed.  相似文献   

6.
A modified leaf disc buoyancy procedure for the detection of photosynthesis-inhibiting residues in water is described. The modifications proposed, mainly the presence of sodium hydrogen carbonate in the infiltration solution, increased the sensitivity of the method and reduced the time required. The substituted urea and 1,3,5-triazine herbicides diuron, linuron, monuron, atrazine, ametryn and atraton were detected below 0.7 mg litre?1 using cucumber (Cucumis sativus L., cv. ‘Dalia’) leaf discs. A concentration as low as 0.09 mg diuron litre?1 could be detected. Although bean (Phaseolus vulgaris L., cv. ‘Bulgarian’) leaf tissue was less sensitive in this bioassay than cucumber, 0.3 mg diuron litre?1 could still be detected. The test, being very rapid (less than 30 min per determination) and relatively sensitive, could be used for the detection of photosynthesis inhibitors in recycled water used for irrigation.  相似文献   

7.
The metabolism of atrazine was studied in resistant and susceptible biotypes of Chenopodium album L., Chenopodium strictum Roth., and Amaranthus powellii S. Wats. Both biotypes metabolized atrazine by N-dealkylation, hydroxy lation at the 2-position and conjugation. In addition, binding of mono-N-dealkylated atrazine with plant constituents to form nonextractable (bound) residues was also observed. Although parent atrazine levels were similar in the shoots and roots of both biotypes of the three weed species, the resistant biotype in each case contained a higher level of polar conjugates and bound residues in the plant tissues. In contrast, presence of a phytotoxic metabolite, namely 2-chloro-4-amino-6-isopropylamino-s-triazine, was only observed in the susceptible biotype of the three weed species.  相似文献   

8.
Wheat (cv. WH-147) and five biotypes of Phalaris minor Retz. (KR-1, H-4, K-2, H-2 and J-1) were treated with isoproturon in controlled environmental conditions to assess their level of resistance. Resistance of P. minor to isoproturon was found in the order of KR-1 > H-4 > K-2 > H-2 = J-1. Compared with the susceptible (S) biotype (H-2), the resistant (R) biotypes (KR-1. H-4 and K-2) of P. minor required 13.0, 4.5 and 2.7 times higher doses of isoproturon for a 50% reduction in growth (GR50) and 2.4 times that of the S biotype (H-2) by wheat. The corresponding figures for KR-1, H-4, K-2 biotypes and wheat were 18, 4.1, 2.4 and 4.6 times based on dry weight reduction. The effect of isoproturon on photosynthesis was studied in vitro using five biotypes of P. minor and in viro with wheat. KR-1 (R) and H-2 (S) biotypes of P. minor. Under in vitro treatment conditions isoproturon inhibited the photosynthesis of all five P. minor biotypes, whereas in vivo the recovery was greater in the R biotype than in the wheat and the S biotype. Effects on chlorophyll fluorescence were also measured in wheat and the KR-1 (R) and H-2 (S) biotypes of P. minor. A 4-h treatment of excised leaves incubaled in isoproluron solution (0.025 and 0.05 mm concentration) resulted in a decreased fluorescence coefficient (Fv Fm ratio in which Fv= variable fluorescence (Fm - Fo): Fm= the maximum fluorescence and Fo= initial fiuorescence) in wheat (Triticum aestivum L.) and both biotypes of P. Minor. The recovery was, however, greater in the R biotype than in wheat and it was completely recovered within 24 h. No recovery was recorded in the case of the S biotype of P. minor and a greater recovery time was required for wheat than the R biotype. The higher dose required for growth inhibition in the R biotype and rapid recovery of oxygen evolution and fluorescence coeflicient under in viro conditions together with the absence of selectivity in vitro suggests that the target site was unaffected. It can be conjectured that resistance to isoproturon is most probably because of enhanced metabolism or sequestration of isoproturon, resulting in decreased target site delivery.  相似文献   

9.
Plants of Amaranthus cruentus and Amaranthus hybridus resistant to atrazine and cyanazine were found in maize fields in north-eastern Spain. Both resistant foiotypes survived doses of 5 kg ha?1 of atrazine and 2–4 kg ha?1 of cyanazine but were controlled by lower doses of bentazone and pyridate than were susceptible biotypes. Such a negative cross-resistance was not found for chloroacetamides and MCPA. Chlorophyll fluorescence studies revealed that atrazine, bentazone, cyanazine and pyridate (10 mg litre?1) caused inhibition of photosynlhetic electron transport in susceptible leaves, while in resistant plants, atrazine and cyanazine had no effect. Conversely, bentazone and pyridate inhibited photosynthesis to a greater extent in resistant than in susceptible biotypes. Isolated chloroplast membranes from resistant biotypes showed resistance factors of 366 and 501 to atrazine and 39 and 60 to cyanazine for A. hybridus and A. cruentus, respectively. Bentazone and pyridate were found to be more effective in chloropiasts of the resistant biotypes than those of the susceptible plants. It is suggested that enhanced susceptibility to bentazone and pyridate in triazine-resistant A. cruentus and A. hybridus biotypes may be associated with the alteration of the D-I polypeptide subunit of photosystem II, as found in triazine-resistant plants.  相似文献   

10.
The herbicide‐binding region of the chloroplast psbA gene from a total of 20 biotypes of Poa annua L resistant and susceptible to metribuzin and diuron was selectively amplified using PCR. Sequence analysis of the fragment from six herbicide‐resistant biotypes of P annua exhibited a substitution from valine to isoleucine at position 219 of the D1 protein encoded by the psbA gene. This is the same mutation as reported for Chlamydomonas and Synechococcus through site‐directed mutagenesis and in cell cultures of Chenopodium rubrum L. To our knowledge this is the first report of a higher plant exhibiting resistance in the field to photosystem II inhibitors due to a psbA mutation other than at position 264. The existence of additional biotypes of P annua resistant to diuron or metribuzin but lacking mutation in the herbicide‐binding region indicates that resistance to these herbicides can also be attained by other mechanisms. © 2000 Society of Chemical Industry  相似文献   

11.
The infestations of two biotypes of Panicum miliaceum L. were monitored over a 5-year period (1981–1985) as they occurred in two townships in southwestern Ontario, Canada. On average, 16·5% of the cultivated fields in Hullett township were infested with the black-seeded biotype while 12·9% of the fields in North Norwich township were infested with the golden-seeded biotype. Neither population showed clear signs of increasing. The two biotypes were similar in their ability to persist as adult infestations. The black-seeded biotype showed a greater potential for colonizing uninfested fields. The crops grown in this region showed different susceptibilities to infestation by P. miliaceum. Corn (maize) fields were susceptible while most grain fields were resistant to infestation. White beans were susceptible to infestation by the black-seeded biotype. Wheat and oat crops were more resistant to infestation by the golden-seeded biotype than to those of the black-seeded biotype.  相似文献   

12.
Three Australian Sisymbrium orientale and one Brassica tournefortii biotypes are resistant to acetolactate synthase (ALS)-inhibiting herbicides due to their possession of an ALS enzyme with decreased sensitivity to these herbicides. Enzyme kinetic studies revealed no interbiotypic differences within species in Km (pyruvate) (the substrate concentration at which the reaction rate is half maximal) but a greater Vmax (the rate when the enzyme is fully saturated with substrate) for two of the resistant S orientale biotypes over susceptible levels. F1 hybrids from reciprocal crosses between resistant and susceptible biotypes of S orientale showed an intermediate response to chlorsulfuron compared to the parental plants. ALS herbicide resistance in S orientale segregated in a 3:1 (resistant:susceptible) ratio in F2 plants with a single rate of chlorsulfuron, indicating that resistance is inherited as a single, incompletely dominant nuclear gene. Two regions of the ALS structural gene known to vary in ALS-resistant biotypes were amplified and sequenced. Resistant S orientale biotypes NS01 and SS03 contained a single nucleotide substitution in Domain B, predicting a Trp (in susceptible) to Leu (in resistant) amino acid change. Two adjacent nucleotide substitutions (CC T to AT T) predicting a Pro (in susceptible) to Ile (in resistant) change in the primary amino acid sequence were identified in Domain A of resistant S orientale biotype SS01. Likewise, a single nucleotide substitution at the same site in the resistant B tournefortii biotype predicts a Pro (in susceptible) to Ala (in resistant) substitution. No other interbiotypic nucleotide differences predicted amino acid changes in the sequenced regions, suggesting that the amino acid substitutions reported above are responsible for resistance to ALS-inhibiting herbicides in the respective biotypes. © 1999 Society of Chemical Industry  相似文献   

13.
Atrazine [2-chloro-4-(ethylaminol-6-(isopropyl-amino)-s-triazine] resistant biotypes of lamb's quarters (Chenopodium athum L) were reported in the maize growing areas of Ontario, where the herbicide had been used fur a number of years. Field samples from four locations proved tolerant to higber than recommended rates of atrazine in controlled environment screening trials. A resistant biotype was not killed with up to 40 kg/ha atrazine. Diuron at 5 x10-5 M inhibited the Hill reaction with isolated chloroplasts of resisiant and susceptible biotypes of lamb's-quarters. However, with 10-4 M atrazine, the photochemical activity was inhibited in chloroplasts isolated from the susceptible biotype but not in chloroplasts from the resisiant biotype. With maize chloroplasts, inhibition with 10-4 M atrazine was the same as with the susceptible biotype of lamb's-quarters. These studies suggested that a new mechanism of intraspecific resistance in lamb's quarters to atrazine was involved, other than differences in uptake, translocation and metabolism reported with interspecific comparisons involving the s-triazines and other herbicides, It was also concluded that atrazine and diuron did not have precisely the same mechanism of action as photosynthetic inhibitors with lamb's-quarters, and that external and or internal structure or function of chloroplasts in relation to atrazine inhibition can vary significantly even in biotypes of the same species.  相似文献   

14.
Herbicide resistance poses a substantial threat to the agricultural industry throughout the world and during the past decade several reports regarding herbicide resistance have been published. Raphanus raphanistrum L., from two wheat farms located in the winter rainfall region of South Africa, showed indications of resistance to chlorsulfuron. Seeds from these suspected resistant biotypes as well as seeds from a susceptible biotype were collected and transported to the ARC-Small Grain Institute for herbicide resistance studies. Herbicides registered for R. raphanistrum control, i.e. chlorsulfuron, MCPA and bromoxynil, were used in this study. Significant differences in the degree of control were found between the susceptible and two resistant biotypes, when treated with chlorsulfuron. The LD50 values for the resistant biotypes (WR 1 & WR 2) were 45 and 11.3 g a.i. ha–1, respectively, whereas the LD50 value for the susceptible biotype was 5.6 g a.i. ha–1. The almost eightfold difference between the susceptible and resistant biotype (WR 1), indicated that resistance has developed to chlorsulfuron. Only twofold resistance was established between the other resistant biotype (WR 2) and the susceptible biotype. Significant differences between herbicide rates were also established with the MCPA and bromoxynil experiments. No significant difference could, however, be found between the susceptible and resistant biotypes when treated with MCPA and bromoxynil, indicating the importance of different modes of action of herbicide as a strategy to prevent herbicide resistance.  相似文献   

15.
Glyphosate is one of the most commonly used broad‐spectrum herbicides over the last 40 years. Due to the widespread adoption of glyphosate‐resistant (GR) crop technology, especially corn, cotton and soybean, several weed species have evolved resistance to this herbicide. Research was conducted to confirm and characterize the magnitude and mechanism of glyphosate resistance in two GR common ragweed ( A mbrosia artemisiifolia L.) biotypes from Mississippi, USA. A glyphosate‐susceptible (GS) biotype was included for comparison. The effective glyphosate dose to reduce the growth of the treated plants by 50% for the GR1, GR2 and GS biotypes was 0.58, 0.46 and 0.11 kg ae ha?1, respectively, indicating that the level of resistance was five and fourfold that of the GS biotype for GR1 and GR2, respectively. Studies using 14 C‐glyphosate have not indicated any difference in its absorption between the biotypes, but the GR1 and GR2 biotypes translocated more 14 C‐glyphosate, compared to the GS biotype. This difference in translocation within resistant biotypes is unique. There was no amino acid substitution at codon 106 that was detected by the 5‐enolpyruvylshikimate‐3‐phosphate synthase gene sequence analysis of the resistant and susceptible biotypes. Therefore, the mechanism of resistance to glyphosate in common ragweed biotypes from Mississippi is not related to a target site mutation or reduced absorption and/or translocation of glyphosate.  相似文献   

16.
The resistance mechanism of Leptochloa chinensis Nees to propanil was investigated, based on propanil metabolism, aryl acylamidase activity, and chlorophyll fluorescence at the 8 week growth stage of L. chinensis. The concentration of propanil in the leaf and culm extracts of the resistant (R) and susceptible (S) biotypes, as measured by gas chromatography (GC), was found to increase after propanil treatment. The concentration of propanil in the leaf and culm extracts of the S biotype at 72 h was 1.55 and 0.49 µg mL?1, respectively. However, a lower concentration of propanil was observed in the R biotype, as compared to that in the S biotype. The residue of 3,4‐dichloroaniline, as measured by GC, was detected only in the leaf extracts of the R biotype. In contrast, no residue of 3,4‐dichloroaniline was observed in the S biotype. The level of aryl acylamidase in the leaf tissue extracts of the R biotype was ～140% higher than that in the S biotype. The fluorescence studies showed that propanil inhibited the quantum efficiency of the photosystem II in both the R and S biotypes after 2 h of incubation time. However, when the leaf disks were transferred and incubated in deionized water for 48 h, the quantum efficiency increased in the R biotype but decreased in the S biotype. These results suggest that propanil metabolism, enhanced by aryl acylamidase activity, is the most likely factor contributing towards the mechanism of propanil resistance in L. chinensis plants at the 8 week growth stage.  相似文献   

17.
The photosynthetic performance of Solarium nigrum L., Poa annua L. and Chenopodium album L. resistant to triazines was investigated in order to determine whether the alteration of the 32-kD protein of photosystem (PS) II changed the ability to oxidize the PSII primary quinone acceptor QA. The effect of heat stress on the photochemistry of the resistant biotypes and the susceptible biotypes was also compared. The weeds were screened with the in-vivo modulated chlorophyll fluorescence device to measure the photochemical component of fluorescence quenching (qQ), which provided semi-quantitative information on the redox state of QA. At 25°C, an increase in the amplitude of the parameter 1-qQ, which reflected the reduced state of QA, was observed in all resistant biotypes, compared to the susceptible wild biotypes. This was attributable to a shift in the equilibrium between QA? and QB (the PSII secondary quinone acceptor) in favour of QA. A heat stress of 35°C did not increase the level of reduced QA, except in the resistant biotypes of Poa annua. The photochemical activity of the two types of leaves exposed to increasingly high temperatures (25–65°C) indicated that quinone oxidation was more affected by heat stress in mutant resistant biotypes than in the susceptible biotypes. The quinone reoxidation was nullified at 60, 56 and 60°C, respectively, for susceptible biotypes of Solatium nigrum, Poa annua and Chenopodium album, and at 56, 48 and 54°C, respectively, for the three resistant biotypes. Heat also induced changes in the dark fluorescence F0, an indicator of the heat sensitivity of the light-harvesting chlorophyll protein complex of PSII (LHCPII). The temperature dependence (25–70°C) of this fluorescence parameter confirmed the higher susceptibility of heat-treated resistant leaves. Indeed, the temperatures of the peak of F0 (Tp) were 60, 55 and 62°C for susceptible Solanum nigrum, Poa annua and Chenopodium album, respectively. The Tp values for the three resistant biotypes were 55, 48 and 57°C, respectively. It is concluded that heat tolerance is related to differences in the organization of the chlorophyll antennae (LHCPII) between the two biotypes. Tolerance de biotypes sensibles et resistants aux triazines de 3 adventices au stress de la chaleur: une étude de fluorescence Les rendements photosynthétiques de Solanum nigrum L., Poa annua L. et Chenopodium album L. resistant aux triazines ont étéétudiés en vue de déterminer dans quelle mesure l'altération de la protéïne 32 kD du photosystème (PS) II, affecte la capacité d'oxyder l'accepteur quinonique primaire de PS II. QA L'influence d'un stress de chaleur sur la photochimie de biotypes résistants et de biotypes sensibles a été comparée. Les mauvaises herbes ont été triées au moyen de la fluorescence de la chlorophylle in vivo, pour mesurer la composante photochimique de réduction de la fluorescence (qQ) qui donne une information semi quantitative de l'état redox de QA. A 25 °C, une augmentation dans l'amplitude du paramètre 1-qQ, qui reflète l'état réduit de QA a été observée chez les biotypes resistants encomparaison des biotypes sauvages sensibles. Ceci a été attribuéà une modification dans l'équilibre entre Q?A et QB (l'accepteur quinonique secondaire PS II), en faveur de QA. Un stress thermique de 35°C n'a pas augmenté le niveau de QA réduit, sauf chez le biotype résistant de Poa annua. L'activité photochimique des feuilles des 2 types exposées à des hautes températures croissantes (25 à 65°C) a montré que l'oxydation de la quinone était plus affectée par le stress thermique chez les biotypes mutants résistants que chez les biotypes sensibles. La réoxydation de la quinone était annulée à 60, 56 et 60°C respectivement pour les biotypes sensibles de Solatium nigrum, Poa annua et Chenopodium album et à 56, 48 et 54°C respectivement pour les 3 biotypes résistants. La chaleur a également entrainé des changements dans la fluorescence F0, un indicateur de la sensibilitéà la chaleur du complexe collecteur de lumière du PS II (LHCP II). La dépendance avec la température (25–70°C) de ce paramètre de fluorescence a confirmé la plus grande sensibilité des feuilles résistantes soumises à la chaleur. En effet, les températures du pic de Fo (Tp) étaient de 60, 55 et 62°C respectivement, pour les biotypes sensibles de Solanum nigrum, Poa annua et Chenopodium album. Les valeurs Tp pour les 3 biotypes résistants étaient respectivement de 55, 48 et 57°C. Il est conclu que la tolérance à la chaleur est liée aux différences dans l'organisation des antennes chlorophylliennes (LHC P II) entre les 2 biotypes. Hitzetoleranz Triazin-resistenter und -empfindlicher Biotypen von drei Unkrautarten Die photosynthetische Leistung Triazin-resistenter Biotypen von Solanum nigrum L., Poa annua L. und Chenopodium album L. wurde dahingehend untersucht, ob eine Veränderung des 32-kD-Eiweisses des Pigmentsystems II (PII) die Fähigkeit änderte, den primären Quinon-Akzeptor QA des PII zu oxidieren. Auch die Wirkung einer Hitzebehandlung auf die photochemischen Reaktionen resistenter und empfindlicher Biotypen wurde verglichen. Die Unkräuter wurden in vivo mit einem Chlorophyll-Fluorimeter gescreent, um die photochemische Komponente der Fluoreszenz-Auslösung (qQ) zu messen, die eine semiquantitative Information über den Redox-Zustand des QA lieferte. Die Amplitude des Parameters l-qQ, der den reduzierten Zustand des QA widerspiegelte, nahm bei 25°C bei allen resistenten Biotypen im Vergleich zu den empfindlichen zu. Dies konnte einer Verschiebung des Gleichgewichts zwischen Q?A und QB (dem sekundären Quinon-Akzeptor QA des PII) zugunsten des QA zugeordnet werden. Eine Hitzebehandlung mit 35°C erhöhte den reduzierten QA nicht, außer bei resistenten Biotypen von Poa annua. Die photochemische Aktivität von Blättern der beiden Typen, die steigenden Temperaturen von 25 bis 65°C unterworden wurden, zeigte, daß die Quinon-Oxidation bei den resitenten Biotypen durch den Hitzestreß stärker beeinflußt wurde als bei den empfindlichen. Die Quinon-Reoxidation wurde bei den empfindlichen Biotypen von Solanum nigrum, Poa annua und Chenopodium album bei 60, 56 bzw. 60°C aufgehoben, bei den resistenten bei 56, 48 bzw. 54°C. Hitze führte auch zu Änderungen der Dunkel-Fluoreszenz Fo, einem Indikator der Hitzeempfindlichkeit des lichtabsorbierenden Chlorophyll-Eiweißkomplexes des PII (LHCPII). Die Temperaturabhängigkeit dieses Fluoreszenz-Parameters bei 25 bis 70°C bestätigte die höhere Empfindlichkeit hitzebehandelter Blätter resistenter Pflanzen. So waren Fo-Peaks bei empfindlichen Solanum nigrum, Poa annua und Chenopodium album bei 60, 55 bzw. 62°C, bei resistenten bei 55, 48 bzw. 57°C festzustellen. Daraus wurde geschlossen, daß die Hitzetoleranz auf Unterschieden im Aufbau des lichtabsorbierenden Pigmentsystems LHCPII der beiden Biotypen beruht.  相似文献   

18.
In Shizuoka Prefecture, Japan, glyphosate‐resistant Lolium multiflorum is a serious problem on the levees of rice paddies and in wheat fields. The mechanism of resistance of this biotype was analyzed. Based on LD50, the resistant population was 2.8–5.0 times more resistant to glyphosate than the susceptible population. The 5‐enolpyruvyl‐shikimate‐3‐phosphate synthase (EPSPS) gene sequence of the resistant biotype did not show a non‐synonymous substitution at Pro106, and amplification of the gene was not observed in the resistant biotype. The metabolism and translocation of glyphosate were examined 4 days after application through the direct detection of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) using liquid chromatograph‐tandem mass spectrometer (LC‐MS/MS). AMPA was not detected in either biotype in glyphosate‐treated leaves or the other plant parts. The respective absorption rates of the susceptible and resistant biotypes were 37.90 ± 3.63% and 41.09 ± 3.36%, respectively, which were not significantly different. The resistant biotype retained more glyphosate in a glyphosate‐treated leaf (91.36 ± 1.56% of absorbed glyphosate) and less in the untreated parts of shoots (5.90 ± 1.17%) and roots (2.76 ± 0.44%) compared with the susceptible biotype, 79.58 ± 3.73%, 15.77 ± 3.06% and 4.65 ± 0.89%, respectively. The results indicate that the resistance mechanism is neither the acquisition of a metabolic system nor limiting the absorption of glyphosate but limited translocation of the herbicide in the resistant biotype of L. multiflorum in Shizuoka Prefecture.  相似文献   

19.
水稻品种对稻褐飞虱抗性的研究   总被引：2，自引：0，他引：2  
水稻品种对褐飞虱的不同生物型反应是不相同的。试验结果证实:(1)褐飞虱若虫在敏感性品种上的生存率显著地高于抗性品种。在TN_1上,无论那种生物型的生存率均很高;而栖息在Mudgo的褐飞虱若虫,其生存率以生物型2的最高,而生物型1与生物型3的均很低,栖息在ASD_7的若虫,以生物型3的生存率最高。(2)褐飞虱在敏感品种上的后代群体密度显著地比抗性品种的大。生活在敏感品种的若虫,发育进度较抗性品种的快,并且身体较重。(3)在敏感品种取食的飞虱,其分泌的蜜露量较抗性品种的多,生物型2取食Mudgo的和生物型3取食ASD_7的均分泌较多的蜜露。上述结果说明了水稻品种抗褐飞虱的机制属抗生性范畴。  相似文献   

20.
Enhanced crop competition could aid in the management of annual sowthistle (Sonchus oleraceus L.), a dominant weed of Australian cropping systems. A two‐year pot study was conducted to evaluate the effect of wheat (Triticum aestivum L.) planting densities (0, 82, and 164 wheat plants/m2) on growth and seed production of glyphosate‐resistant (GR) and glyphosate‐susceptible (GS) biotypes of annual sowthistle. Without competition, both biotypes produced a similar number of leaves and biomass, but the GS biotype produced 80% more seeds (46,050 per plant) than the GR biotype. In competition with 164 wheat plants/m2, the number of leaves in the GR and GS biotypes was reduced by 62 and 61%, respectively, in comparison with the no‐competition treatment, and similarly, weed biomass was reduced by 78 and 77%, respectively. Compared to no‐competition treatment, the seed production of GR and GS biotypes was reduced by 33 and 69%, respectively, when grown with 82 wheat plants/m2, but increasing wheat density from 82 to 164 plants/m2 reduced the number of seeds only in the GS biotype (81%). Both biotypes produced greater than 6,000 seeds per plant when grown in competition with 164 plants/m2, suggesting that increased crop density should be integrated with other weed management strategies for efficient control of annual sowthistle.  相似文献   

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