Plant Physiol, January 2001, Vol. 125, pp. 241-251
Dynamic Localization of Rop GTPases to the Tonoplast during
Vacuole Development1
Yakang
Lin,2
Darren F.
Seals,
Stephen K.
Randall, and
Zhenbiao
Yang*
Department of Botany and Plant Sciences, University of California,
Riverside, California 92521 (Y.L., Z.Y.); and Department of
Biology, Indiana University-Purdue University, Indianapolis, Indiana
46202 (D.F.S., S.K.R.)
Vacuoles are essential pleomorphic organelles that undergo
dynamic changes during cell growth and differentiation in plants. How
developmental signals are linked to vacuole biogenesis and development
is poorly understood. In this report, we show that a Rop GTPase is
localized to developing vacuoles in pea (Pisum sativum cv Extra Early Alaska). Rop belongs to the RHO
family of Ras-related small GTP-binding proteins that are key molecular switches in a wide variety of eukaryotic signal transduction pathways. Using indirect immunofluorescence and an anti-Rop antibody, we showed
that Rop proteins accumulate to high levels in rapidly growing tapetal
cells of pea anthers. In these cells, Rop is localized to an
endomembrane system that exists as dynamic pleomorphic networks: a
perinuclear fine network decorated with punctate dots, a network composed of small spheres and tubules, and interconnected chambers. Colocalization with a tonoplast annexin VCaB42 shows that these dynamic
networks represent the tonoplast. Our results suggest that the dynamic
Rop-containing tonoplast networks represent a unique stage of vacuole
development. The specific localization of Rop to developing vacuoles
supports a role for Rop in signal transduction that mediates vacuole
development in plants.
1
This work was supported by the U.S. Department
of Agriculture (grant no. 96-35304-3861), the National Science
Foundation (grant no. MCB-9724047 to Z.Y.), and a Purdue Research
Foundation grant (to S.R.).
2
Present address: Plant Biotechnology Center, Ohio State
University, Columbus, OH 43210.
*
Corresponding author; e-mail zhenbiao.yang{at}ucr.edu; fax
909-787-4437.
© 2001 American Society of Plant Physiologists
