INVESTIGADORES
GOLDRAIJ ariel
artículos
Título:
Disorganization of F-actin cytoskeleton precedes vacuolar disruption in pollen tubes during the in vivo self-incompatibility response in Nicotiana alata
Autor/es:
JUAN A ROLDÁN; HERNÁN ROJAS; ARIEL GOLDRAIJ
Revista:
ANNALS OF BOTANY
Editorial:
OXFORD UNIV PRESS
Referencias:
Lugar: Oxford; Año: 2012 vol. 110 p. 787 - 795
ISSN:
0305-7364
Resumen:
Background and Aims The integrity of actin
filaments (F-actin) is essential for pollen tube growth. In S-RNase-based
self-incompatibility (SI), incompatible pollen tubes are inhibited in the
style. Consequently, research efforts have focused on the alterations of pollen
F-actin cytoskeleton during the SI response. However, so far, these studies
were carried out in in vitro-grown
pollen tubes. This study aimed to assess the timing of in vivo changes of pollen F-actin cytoskeleton taking place
after compatible and incompatible pollinations in Nicotiana
alata. To our knowledge, this is the first report of the in vivo F-actin alterations occurring during
pollen rejection in the S-RNase-based SI system.
Methods The F-actin cytoskeleton and the
vacuolar endomembrane system were fluorescently labeled in compatibly and
incompatibly pollinated pistils at different times after pollination. The
alterations induced by the SI reaction in pollen tubes were visualized by
confocal laser scanning microscopy.
Key Results Early after pollination, about 70%
of both compatible and incompatible pollen tubes showed an organized pattern of
F-actin cables along the main axis of the cell. While in compatible
pollinations this percentage was unchanged until pollen tubes reached the
ovary, pollen tubes of incompatible pollinations underwent gradual and
progressive F-actin disorganization. Colocalization of the F-actin cytoskeleton
and the vacuolar endomembrane system, where S-RNases are compartmentalized,
revealed that by day six after incompatible pollination, when the pollen tube
growth was already arrested, about 80% of pollen tubes showed disrupted F-actin
but a similar percentage had intact vacuolar compartments.
Conclusions Results indicate that during the
SI response in Nicotiana, disruption of
the F-actin cytoskeleton precedes vacuolar membrane breakdown. Thus,
incompatible pollen tubes undergo a sequential disorganization process of major
subcellular structures. Results also suggest that the large pool of S-RNases
released from vacuoles acts late in pollen rejection, after significant
subcellular changes in incompatible pollen tubes.