Vessel development and the importance of lateral flow in water transport within developing bundles of current-year shoots of grapevine (Vitis vinifera L.)
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Date
2012
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
In the developing xylem bundles of young
stems, the presence of immature living vessel elements can
strongly restrict or even block axial hydraulic conductance,
especially in newly matured vessels. Lateral connections
between vessels may provide an alternative pathway for
water movement to bypass these closed, living elements.
Using the grapevine as a model system, the present study
aimed to demonstrate the effects of living vessel elements
on water movement patterns, and the importance of lateral
flow for effective water conductivity in the developing
bundles. Living vessel elements were detected using dye
staining and the pattern of vessel development and maturation
was then monitored. The importance of lateral flow
was confirmed using several approaches: (1) capacity for
lateral flow, (2) effect of increasing the distance of water
transport, and (3) effect of ion concentrations. Living
vessel elements were found along the developing bundles,
they occupied a significant proportion of the distal and
peripheral parts of the flow path, forming a substantial
barrier to apoplastic water flow. Water in the developing
xylem bundles could move easily from vessel to vessel and
between secondary and primary xylem. Furthermore, data
from increasing the transport length and altering the ion
concentrations supported the critical contribution of the
lateral flow to the total hydraulic conductance within the
developing bundles. The hydraulic architecture of the
developing xylem bundles is described. The results are
discussed in terms of reliability and efficiency of water
transport during shoot growth and development.
Description
Keywords
Axial flow, Developing bundles, Intervessel contacts, Grapevine, Lateral flow, Lateral pathways, Living vessel elements