Expression and distribution of a vacuolar aquaporin in young and mature leaf tissues of Brassica napus in relation to water fluxes

Frangne, Nathalie; Maeshima, Masayoshi; Schäffner, Anton R.; Mandel, Therese; Martinoia, Enrico; Bonnemain, Jean-Louis (2001). Expression and distribution of a vacuolar aquaporin in young and mature leaf tissues of Brassica napus in relation to water fluxes. Planta, 212(2), pp. 270-278. Springer 10.1007/s004250000390

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Recently, it has been shown that water fluxes across biological membranes occur not only through the lipid bilayer but also through specialized water-conducting proteins, the so called aquaporins. In the present study, we investigated in young and mature leaves of Brassica napus L. the expression and localization of a vacuolar aquaporin homologous to radish γ-tonoplast intrinsic protein/vacuolar-membrane integral protein of 23 kDa (TIP/VM 23). In-situ hybridization showed that these tonoplast aquaporins are highly expressed not only in developing but also in mature leaves, which export photosynthates. No substantial differences could be observed between different tissues of young and mature leaves. However, independent of the developmental stage, an immunohistochemical approach revealed that the vacuolar membrane of bundle-sheath cells contained more protein cross-reacting with antibodies raised against radish γ-TIP/VM 23 than the mesophyll cells. The lowest labeling was detected in phloem cells. We compared these results with the distribution of plasma-membrane aquaporins cross-reacting with antibodies detecting a domain conserved among members of the plasma-membrane intrinsic protein 1 (PIP1) subfamily. We observed the same picture as for the vacuolar aquaporins. Furthermore, a high density of gold particles labeling proteins of the PIP1 group could be observed in plasmalemmasomes of the vascular parenchyma. Our results indicate that γ-TIP/VM 23 and PIP1 homologous proteins show a similar expression pattern. Based on these results it is tempting to speculate that bundle-sheath cells play an important role in facilitating water fluxes between the apoplastic and symplastic compartments in close proximity to the vascular tissue.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS) > Plant Development
08 Faculty of Science > Department of Biology > Institute of Plant Sciences (IPS)

UniBE Contributor:

Mandel, Therese and Martinoia, Enrico

Subjects:

500 Science > 580 Plants (Botany)

ISSN:

0032-0935

Publisher:

Springer

Language:

English

Submitter:

Peter Alfred von Ballmoos-Haas

Date Deposited:

02 Jun 2016 08:09

Last Modified:

02 Jun 2016 08:09

Publisher DOI:

10.1007/s004250000390

Uncontrolled Keywords:

Aquaporin, localization, Brassica, (aquaporin), Plasma membrane, Vacuolar membrane, Water flux

BORIS DOI:

10.7892/boris.81031

URI:

https://boris.unibe.ch/id/eprint/81031

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