Distribution of ¹⁴C‐glyphosate in legumes parasitised by Orobanche crenata. Répartition du glyphosate ¹⁴C dans des légumes parasités par Orobanche crenata

Abstract

Absorption and translocation of '"C-glyphosate was evaluated under controlled conditions in peas (Pisum sativum L.) and broad beans (Viciafaba L.) parasitised or not by crenate broomrape Orobanche crenata Forsk.), Absorption increased with time up to 12 days after treatment, and reached about 50% of the '"C-glyphosate applied. Three days after treatment 70-85% of the total herbicide absorbed had been translocated out of the treated leaflet. There was no consistent difference in absorption and translocation between infected and non-infected plants 12 days after treatment. The '^C-glyphosate concentration in the root system increased with time in broad beans. In peas it remained more or less constant from 3 days after treatment. Generally, pods were stronger sinks for glyphosate than other parts of the plant. Herbicide accumulation in broomrape increased with its growth stage, and the parasite was a much stronger sink for glyphosate than the legume root system.A. Arjona-Berral. J. Mesa-Garcia and L. Garcia-Torres blieb sie nach 3 Tagen nach der Behandlung mehr Oder weniger konstant. In die Hulsen wurde im allgemeinen mehr Glyphosat verlagert als in andere Teile der PHanzen. In der Orobanche nahm die Akkumulation des Herbizids mit dem Wuchsstadium zu und war viel groBer als im Wurzelsystem der Gemusepflanzen.

Effect of Glyphosate on Performance of Faba Bean Varieties Under Heavy Infestation of Orobanche crenata

“…Around that time O.crenata seed germination would have been triggered by the faba bean root exudates and germinated seeds would have attached themselves using the haustorium. Once successful in root penetration, the haustorium becomes the physiological connection between the parasite and faba bean, channeling water and photo-assimilates to the parasite, thus creating a new strong sink below the soil surface (Arjona-Berral et al 1990). At this delicate phase, if pod filling has already been initiated on the faba bean plant, partitioning of assimilate between the two sinks (parasite and the pod) occurs, however, if pod filling was not achieved by that time, the below-ground sink (parasite) suppresses the formation of the above-ground sink (pods) as indicated by Manschadi et al (1997).…”

“…At this delicate phase, if pod filling has already been initiated on the faba bean plant, partitioning of assimilate between the two sinks (parasite and the pod) occurs, however, if pod filling was not achieved by that time, the below-ground sink (parasite) suppresses the formation of the above-ground sink (pods) as indicated by Manschadi et al (1997). It is at this critical phase, that when glyphosate is introduced to the host in low concentrations, translocation of the herbicide molecules was observed to be greater in the direction of the haustorium leading to the accumulation of the herbicide in the parasite tissue causing growth disruption (Arjona-Berral et al 1990). This however, comes at an expense, where signs of phytotoxicity effects of the herbicide start showing on the faba bean plants, including leaf wrinkling and chlorosis .…”

Secondary Effects of Glyphosate Action in Phelipanche aegyptiaca: Inhibition of Solute Transport from the Host Plant to the Parasite

“…In the host-parasite system, organic carbon, nitrogen and some minerals are transported primarily via the phloem (Hibberd et al, 1999 ; Hibberd and Jeschke, 2001 ). Translocation to the parasite of small molecules, such as sugars, herbicides and possibly amino acids, also takes place, as has been previously described in some members of the genus Orobanche (Aber et al, 1983 ; Arjona-Berral et al, 1990 ; Nandula et al, 1999 ; Diaz-Sanchez et al, 2002 ). In addition, it is known that macromolecules are also transported in the host-parasite system.…”

The Effects of Herbicides Targeting Aromatic and Branched Chain Amino Acid Biosynthesis Support the Presence of Functional Pathways in Broomrape

“…These results may demonstrate a direct influence of imazapic on the parasite, or an effect via interruption of transport between the host and the parasite. However, translocation from host to parasite has never been reported for ALS-inhibiting herbicides, although it has been proven for glyphosate (Arjona-Berral et al, 1990; Nandula et al, 1999). Thus, we determined the level of imazapic in the leaves and roots, and in P. aegyptiaca attached to the roots of HRT plants treated with imazapic.…”

“…Glyphosate has been shown to be translocated from the foliage of treated host plants to broomrape attachments on their roots (Arjona-Berral et al, 1990; Nandula et al, 1999). However, with respect to ALS-inhibiting herbicides, accumulation of radioactivity in sunflower broomrape following application of 14 C-labeled imazapyr has been reported (Dıaz-Sanchez et al, 2002), but this cannot be used as a direct indication of the transfer of non-metabolized herbicide molecules to the parasite.…”