Tumour development in Arabidopsis thaliana involves the Shaker-like K+ channels AKT1 and AKT2/3.
After completion of the Arabidopsis genome-sequencing programme, crown galls induced by Agrobacterium tumefaciens may become a model system to study plant tumour development. The molecular mechanisms of nutrient supply to support tumour growth and development are still unknown. In this study, we have identified a unique profile of Shaker-like potassium channels in agrobacteria-induced Arabidopsis tumours. Comparing the gene expression pattern of rapidly growing tumours with that of non-infected tissues, we found the suppression of shoot in favour of root-specific K+ channels. Among these, the upregulation of AKT1 and AtKC1 and the suppression of AKT2/3 and GORK were most pronounced. As a consequence, K+ uptake and accumulation were elevated in the tumour (163 mm) compared to control tissues (92 mm). Patch clamp studies on tumour protoplasts identified a population expressing the electrical properties of the AKT1 K+ channel. Furthermore, plants lacking a functional AKT1 or the AKT2/3 phloem K+ channel gene did not support tumour growth. This indicates that the delivery of potassium by AKT1 and the direction of assimilates, triggered by AKT2/3, are essential for tumour growth.
Deeken
Rosalia
R
Julius-von-Sachs-Institut für Molekulare Pflanzenphysiologie und Biophysik, Universität Würzburg, Julius-von-Sachs-Platz 2, D-97082 Würzburg, Germany.
Ivashikina
Natalya
N
Czirjak
Tina
T
Philippar
Katrin
K
Becker
Dirk
D
Ache
Peter
P
Hedrich
Rainer
R
D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002412:Cations; D015972:Gene Expression Regulation, Neoplastic; D018506:Gene Expression Regulation, Plant; D008564:Membrane Potentials; D009154:Mutation; D018408:Patch-Clamp Techniques; D018547:Plant Stems / Q000235:genetics / Q000378:metabolism; D010941:Plant Tumors / Q000382:microbiology; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*
C097485:AKT2 protein, Arabidopsis; C431716:AKT3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D002412:Cations; D015221:Potassium Channels; C074500:AKT1 protein, Arabidopsis; D011188:Potassium