Self-incompatibility in Papaver rhoeas activates nonspecific cation conductance permeable to Ca2+ and K+.
Plant Physiol
; 155(2): 963-73, 2011 Feb.
Article
em En
| MEDLINE
| ID: mdl-21177472
ABSTRACT
Cellular responses rely on signaling. In plant cells, cytosolic free calcium is a major second messenger, and ion channels play a key role in mediating physiological responses. Self-incompatibility (SI) is an important genetically controlled mechanism to prevent self-fertilization. It uses interaction of matching S-determinants from the pistil and pollen to allow "self" recognition, which triggers rejection of incompatible pollen. In Papaver rhoeas, the S-determinants are PrsS and PrpS. PrsS is a small novel cysteine-rich protein; PrpS is a small novel transmembrane protein. Interaction of PrsS with incompatible pollen stimulates S-specific increases in cytosolic free calcium and alterations in the actin cytoskeleton, resulting in programmed cell death in incompatible but not compatible pollen. Here, we have used whole-cell patch clamping of pollen protoplasts to show that PrsS stimulates SI-specific activation of pollen grain plasma membrane conductance in incompatible but not compatible pollen grain protoplasts. The SI-activated conductance does not require voltage activation, but it is voltage sensitive. It is permeable to divalent cations (Ba(2+) ≥ Ca(2+) > Mg(2+)) and the monovalent ions K(+) and NH(4)(+) and is enhanced at voltages negative to -100 mV. The Ca(2+) conductance is blocked by La(3+) but not by verapamil; the K(+) currents are tetraethylammonium chloride insensitive and do not require Ca(2+). We propose that the SI-stimulated conductance may represent a nonspecific cation channel or possibly two conductances, permeable to monovalent and divalent cations. Our data provide insights into signal-response coupling involving a biologically important response. PrsS provides a rare example of a protein triggering alterations in ion channel activity.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Papaver
/
Proteínas de Plantas
/
Potássio
/
Cálcio
/
Canais Iônicos
Idioma:
En
Revista:
Plant Physiol
Ano de publicação:
2011
Tipo de documento:
Article
País de afiliação:
Reino Unido