Arabidopsis NPCC6/NaKR1 is a phloem mobile metal binding protein necessary for phloem function and root meristem maintenance.
Plant Cell
; 22(12): 3963-79, 2010 Dec.
Article
en En
| MEDLINE
| ID: mdl-21193571
ABSTRACT
SODIUM POTASSIUM ROOT DEFECTIVE1 (NaKR1; previously called NPCC6) encodes a soluble metal binding protein that is specifically expressed in companion cells of the phloem. The nakr1-1 mutant phenotype includes high Na(+), K(+), Rb(+), and starch accumulation in leaves, short roots, late flowering, and decreased long-distance transport of sucrose. Using traditional and DNA microarray-based deletion mapping, a 7-bp deletion was found in an exon of NaKR1 that introduced a premature stop codon. The mutant phenotypes were complemented by transformation with the native gene or NaKR1-GFP (green fluorescent protein) and NaKR1-ß-glucuronidase fusions driven by the native promoter. NAKR1-GFP was mobile in the phloem; it moved from companion cells into sieve elements and into a previously undiscovered symplasmic domain in the root meristem. Grafting experiments revealed that the high Na(+) accumulation was due mainly to loss of NaKR1 function in the leaves. This supports a role for the phloem in recirculating Na(+) to the roots to limit Na(+) accumulation in leaves. The onset of root phenotypes coincided with NaKR1 expression after germination. The nakr1-1 short root phenotype was due primarily to a decreased cell division rate in the root meristem, indicating a role in root meristem maintenance for NaKR1 expression in the phloem.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Arabidopsis
/
Meristema
/
Metales Pesados
/
Proteínas de Arabidopsis
/
Floema
Idioma:
En
Revista:
Plant Cell
Asunto de la revista:
BOTANICA
Año:
2010
Tipo del documento:
Article
País de afiliación:
Estados Unidos