We assessed the effects of Cu on root growth and morphology of stone pine (Pinus pinea L.) and maritime pine (Pinus pinaster Ait.) seedlings grown in culture solutions supplied with 0.012 (control), 0.1, 1 or 5 micro M CuSO(4). The presence of 5 micro M Cu in the nutrient solution completely inhibited root growth of both species within 3 days. In both species, taproot elongation was reduced in the presence of 1 micro M Cu, although partial growth recovery occurred after 7 days of treatment. The presence of 0.1 micro M Cu in the culture solution slightly enhanced root elongation in P. pinaster, but did not significantly influence root elongation in P. pinea. In both species, root weight per unit length increased in response to Cu exposure, and in P. pinaster, root diameter was significantly increased. The Cu treatments also affected lateral root number and length. In the presence of 1 micro M Cu, both species formed only short lateral primordia. The 1 micro M Cu treatment increased the lateral root index (number of roots per cm of root length) of P. pinaster, but decreased that of P. pinea, compared with control values. Neither the 0.1 nor 1 micro M Cu treatment had a significant effect on the mitotic index of either species. We conclude that cell elongation is more sensitive to Cu than cell division. Cell membrane damage, as indicated by Trypan blue staining, occurred after 10 days of exposure to 1 micro M Cu.

1994. Cadmium and copper change root growth and morphology of Pirms pinea and Pinus pinaster seed!ings. -Physiol. Plant. 92: 675-680.Heavy metal loads in forest soils have been increasing over time due to atmospheric inputs. Accumulation in tlie upper soi! layers could affect establishment of seed!ings and forest regeneration. Mediterranean species show a high initia! root development, allowing seedlings to reach the moisture of deeper soil !ayers. In the present work seed!ings of stone pine (Pinus pinea L.) and maritime pine (Pinus pinaster Ait), were grown in culture so!ution supp!ied with 0.0, 0.1, 1 or 5 |iM CdS04 or with 1 \M CdSOj and 1 (tJWCuSO4 combined. !n both species tap-root elongation was drastical!y reduced in the 5 \xM Cd'* and in the (Cd-* + Cu-*) treatments. A supp!y of 0.! or 1 \iM Cd-*, however, enhanced root e!ongation in Pinus pinea without significant!y influencing root elongation in Pinus pinaster. In both species the root density (weight per unit !ength) and the width of the cortex increased in response to Cd-* exposure. In Pinus pinaster the mitotic index decreased at the higher Cd-* concentrations and when Cd^* and Cu^* were combined. The data suggest that ce!l elongation is more sensitive to Cd^* than cell division. The number and length of tlie lateral roots were also affected by Cd-* treatment to a higher degree in Pinus pinaster than in Pinus pinea, reflecting the different Cd-tolerance of the two species.

No abstract

1996, Cadmium and copper uptake and distribution in Mediterranean tree seedlings, -Physiol, Plant. 97: 111-117, Copper and cadmium uptake and distribution in 2-week-old seedlings of stone pine (Pinus pinea L), maritime pine (Pinus pinaster Ait.) and ash (Fraxinus angustifoliaVahl.) were investigated. Seedlings were grown in culture solution at increasing concentrations of CuSO, (0.012-5 ]iM) and CdSO, (0,0-5 pM), All spedes accumulated copper in a larger amount than cadmium. Translocation to the shoot was strongly restricted for both metals, though higher cadmium mobility within the plant could be evidenced. A strong relationship between root content and growth inhibition was detected in the roots in response to copper but not to cadmium treatments. Among species P pinea seemed to be more tolerant to cadmium, whereas F. angustifolia was highly sensitive to both cadmium and copper. X-ray microanalysis of root tip sections showed that copper and cadmium only accumulated in the root tips of F. angustifolia. copper mostly in the cell walls of the cortex layer, cadmium in the inner compartments of the cortex cells. It is suggested that in the two Pinus species the well developed root cap plays a protecting role against metal uptake at the root-dp zone.

Copper and cadmium uptake and distribution in 2-week-old seedlings of stone pine (Pinus pinea L.), maritime pine (Pinus pinaster Ait.) and ash (Fraxinus angustifolia Vahl.) were investigated. Seedlings were grown in culture solution at increasing concentrations of CuSO4 (0.012-5 mu M) and CdSO4 (0.0-5 mu M). All species accumulated copper in a larger amount than cadmium, Translocation to the shoot was strongly restricted for both metals, though higher cadmium mobility within the plant could be evidenced. A strong relationship between root content and growth inhibition was detected in the roots in response to copper but not to cadmium treatments, Among species P. pinea seemed to be more tolerant to cadmium, whereas F: angustifolia was highly sensitive to both cadmium and copper. X-ray microanalysis of root tip sections showed that copper and cadmium only accumulated in the root tips of F. angustifolia, copper mostly in the cell walls of the cortex layer, cadmium in the inner compartments of the cortex cells. It is suggested that in the two Pinus species the well developed root cap plays a protecting role against metal uptake at the root-tip zone