Influence of the acetolactate synthase inhibitor metsulfuron-methyl on the operation, regulation and organisation of photosynthesis in Solanum nigrum

Abstract

The influence of the acetolactate synthase inhibitor metsulfuron-methyl on the operation of the photosynthetic apparatus was examined on 4-weeksold climate chamber-grown Solanum nigrum plant. To have an indication on the relative performance of the photosynthetic apparatus of ALS-treated plants, the level of carbon dioxide (CO 2 ) fixation, the relative quantum efficiency of photosystem I (F PSI ) or photosystem II (F PSII ) electron transport and leaf chlorophyll content were assessed for both control and treated plants at 2, 4 and 7 days after application of the herbicide. Results indicated a progressive inhibition of the level of CO 2 fixation, the relative quantum efficiency of photosystem I (F PSI ) and II (F PSII ) electron transport and the leaf chlorophyll content already 2 days after application of the herbicide. The linear relationship between the photosystem I and II was unaltered by herbicidal treatment and was sustained under conditions where large changes in pigment composition of the leaves occurred. It appears that the stressinduced loss of leaf chlorophyll is not a catastrophic process but rather is the consequence of a well-organised breakdown of components. Under photorespiratory and non-photorespiratory conditions, the relationship between the index of electron transport flow through photosystem I and II and the rate of CO 2 fixation is altered so that electron transport becomes less efficient at driving CO 2 fixation.Keywords Herbicide AE Photosystem I AE Photosystem II AE Quantum efficiency AE Sulfonylurea AE CO 2 fixation AE Chlorophyll AE Chlorophyll fluorescence Abbreviations ALS acetolactate synthase DAT days after treatment HRAC herbicide resistance action committee F PSI relative quantum efficiency of photosystem I F PSII relative quantum efficiency of photosystem II

The effect of field dodder (Cuscuta campestris Yunck.) on morphological and fluorescence parameters of giant ragweed (Ambrosia trifida L.)

“…The other fluorescence parameters (Fm, ETR and IF) were unaffected by C. campestris, and were consequently excluded from further study. The stressful influence of C. campestris on A. trifida led to reductions in the parameters Fv, Fv/Fm and Φ PSII , which is consistent with reports from other studies (Abbaspoor et al, 2006;Riethmuller-Haage et al, 2006) that confirmed lower values of these parameters in plants exposed to stress caused by various factors. Contrarily, C. campestris was found to increase Fo values in host plants, compared to non-infested plants, which is consistent with data showing that Fo values also increased after stressful activity of herbicides in sunflower plants (Božić, 2010).…”

Chlorophyll fluorescence imaging: a new method for rapid detection of herbicide resistance in Alopecurus myosuroides

“…Our findings are in line with studies by Riethmüller‐Haage et al . (,b), Judy et al . () and Percival and Baker ().…”

“…Riethmüller‐Haage et al . (,b) and Kempenaar et al . () showed that herbicides with different modes of action including PSII‐inhibitors, ALS‐inhibitors and auxin‐like herbicides, caused a rapid increase in the relative quantum efficiency of photosystem II and photosystem I electron transport in different weed species shortly after herbicide application.…”

Determining the limitations and regulation of photosynthetic energy transduction in leaves

“…A valuable feature of k e is that it is absolute, not relative like Φ PSI . This allows comparisons to be made between leaves and for the basis of changes in the relationship between Φ PSI and PPFD relationship to be analysed in terms of changes in k e (Riethmuller‐Haage et al. 2006).…”