Download study of the expression and the localization of carrot potassium

STUDY OF THE EXPRESSION AND THE LOCALIZATION
POTASSIUM CHANNEL KDC1 DURING PLANT DEVELOPMENT
OF
CARROT
Alex Costa1, Armando Carpaneto2, Serena Varotto3, Elide Formentin1, Oriano Marin1,
Mario Terzi1, Franco Gambale2 and Fiorella Lo Schiavo1
1
CRIBI, Centro Interdipartimentale per le Biotecnologie Innovative, Università di Padova, Viale G.
Colombo 3, 35121 Padova, Italy;; 2Istituto di Cibernetica e Biofisica-CNR, Via DeMarini 6, 16149
Genova, Italy; 3Dipartimento di Agronomia Ambientale e Produzioni Vegetali, Università di
Padova, Agripolis-Via Romea 16, 35020 Legnaro (Padova), Italy
The expression pattern of the kdc1 gene, coding for an inwardly directed K+ channel of
Daucus carota, is described in several plant tissues and embryo stages. Relative quantitative
RT-PCR experiments indicated that the kdc1 transcript is preferentially expressed in plant
roots, but is also present in other tissues, and in particular, in the shoot apical meristem.
During (somatic) embryonic development, the kdc1 transcript appears as early as the
globular stage, and the transcript level remains constant throughout the successive heart
and torpedo stages. In situ hybridisation experiments showed that kdc1 mRNA is
detectable preferentially in root hairs, root epidermis and endodermis, but is also observed
in single cell layers corresponding to L1 (protoderm) of the shoot apical meristem and leaf
primordia. In embryos, the hybridisation signal is particularly evident in protoderm cells
with a stage dependent expression pattern. Studies with the -glucuronidase promoter
confirm preferential expression of kdc1 at the level of embryo protoderm cells and, in
plant, in root epidermis and root hairs. Western blot analysis of embryonic proteins and
immunolocalisation experiments on somatic embryos sections revealed the presence of
KDC1 during embryo development. Patch-clamp experiments, performed on protoplasts
isolated from embryos at the torpedo stage demonstrated the presence of two types of
functional inward rectifying K+ channels having different amplitudes, kinetics and
threshold of current activation. This would be the first case of a plant ionic channel
analysed during embryo development