Evidence that ethylene signalling is not involved in selective root placement by tobacco plants in response to nutrient-rich soil patches.
Ethylene is a strong controller of root development, and it has been suggested that it is involved in the increase of lateral root development in nutrient-rich soil patches (selective root placement). Here, this contention was tested by comparing selective root placement of an ethylene-insensitive transgenic tobacco (Nicotiana tabacum) genotype (Tetr) with that of wild-type (Wt) plants. Wt and Tetr plants were grown in pots with locally increased nitrate or phosphate concentrations, after which the root growth patterns were compared with those of plants grown in pots with homogeneous nutrient distribution. Tetr plants responded to nutrient patches in a similar way to Wt plants, by placing their roots preferentially at locations with higher nutrient content, and other aspects of plant morphology were also not greatly influenced by ethylene insensitivity. The response of both Wt and Tetr plants to high-nitrate patches was considerably stronger than to locally high phosphate, suggesting that the two responses are not linked in any functional or regulatory way. As the response to nutrient patches was similar in ethylene-sensing and ethylene-insensitive plants, it is concluded that selective root placement in response to nitrate or phosphate is, at least in tobacco, not mediated or modified by ethylene action.
Visser
Eric J W
EJW
Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands.
Bögemann
Gerard M
GM
Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands.
Smeets
Maaike
M
Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands.
De Bruin
Susanne
S
Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands.
De Kroon
Hans
H
Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, the Netherlands.
Bouma
Tjeerd J
TJ
NIOO-KNAW Centre for Estuarine and Marine Ecology, Korringaweg 7, 4401 NT Yerseke, the Netherlands.
D005030:Ethylenes / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development* / Q000378:metabolism; D030821:Plants, Genetically Modified; D015398:Signal Transduction; D012987:Soil; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
D005030:Ethylenes; D012987:Soil; C036216:ethylene