Re: [IAWA Forum] another information about radial water pathway

From: "Veronica Angyalossy Alfonso" <valfonso@ib.usp.br>
Subject: Re: [IAWA Forum] another information about radial water pathway
Date: Sun, 13 Oct 2002 18:01:05 -0300
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Hi,

Only to give another information about Mangrove "supporting roots" -
Rhizophora mangle, Rhizophoraceae.

Nanuza Luiza de Menezes, a professor from our Department, presented a paper
on the XV International Botanical Congress - Yokohama, Japan, 1993 (paper
3153), and showed that this aerial structures are, in reality, stem branches
with a positive geotropism, wich form a great deal of roots in contact with
the water. At the vascular tissue, the protoxylem appears internally to the
metaxylem. This paper is now on press.

Veronica Angyalossy Alfonso
Departamento de Botânica
Instituto de Biociências
Unoversidade de São Paulo





----- Original Message -----
From: MITSUO SUZUKI <mitsuos@mail.cc.tohoku.ac.jp>
To: <iawa@COF.ORST.EDU>
Sent: Monday, October 07, 2002 9:01 PM
Subject: [IAWA Forum] another information about radial water pathway


> I would like to inform you about a typical radial intercellular space
system
> which will serve for water conduction.
> We presented the following paper on 5th Pacific Regional Wood Anatomy
> Conference, Yogyakarta, 2002.
>
> (draft of abstract)
> Specialized water-conducting system in roots of a mangrove plant,
Sonneratia
> alba.
>
> Suzuki, M.12, Sun, Q. 2, Kobayashi, K. 1, Prunbasuki, H. 1 & Suzuki, H. 2
> (1: Botanical Garden, Graduate School of Science, Tohoku University,
Sendai
> 980-0862, Miyagi, Japan; 2:Photodynamics Research Center, RIKEN, Sendai
> 980-0845, Miyagi, Japan)
>
> Mangrove plants develop highly specialized root system for
> adaptation to littoral habitat. Sonneratia alba (Sonneratiaceae) has quite
> complicated root system. It radiates $B%a(Bcable roots$B%b(B
horizontally in the
> ground. The cable roots are anchored by $B%a(Banchoring roots$B%b(B
which are growing
> downwards in the soil. Cable roots bear $B%a(Bpneumatophores$B%b(B
with a certain
> intervals. Pneumatophores grow upwards and finally about uppermost 1/3 of
> them are exposed in the air/sea water. From lateral sides of the under 2/3
> of the pneumatophores, $B%a(Bfeeding roots$B%b(B come out. Feeding
roots run
> horizontally and bear many minute roots just look-like as root hairs of
> terrestrial plants. In usual, mangrove plants do not have root hair.
> As cable roots and pneumatophores are thick since their origin
> (large root apices), it will be expected that they will have no function
to
> absorbing water. As feeding root has much amount of very fine lateral
roots,
> it is only candidate that can serve water absorption, while anchoring
roots
> are medium in size and consequently they may partly function for
absorption.
> Water absorbed by feeding roots move to trunk via a pneumatophore and a
> cable root.
> Pneumatophores are extremely specialized roots in morphology and function.
> They grow only upwards and never branch. They show conspicuous secondary
> growth and form a spindle-like shape. It is generally believed that the
> important function of pneumatophores is oxygen aspiration from air and gas
> conduction for roots which are developing underground. They have
> lenticel-like structure on surface which are exposing in air and
aerenchyma
> is well developed in cortex. Actually, air conduction is one of the
> important functions of pneumatophores, but water conduction is also very
> important function of them.
> Another important function of pneumatophores is water conduction. Water
> absorbed by epidermis of feeding roots enters xylem through endodermis
just
> same as ordinal terrestrial plants. Water them enter to pneumatophore
> secondary xylem. In the secondary xylem, water move horizontally using ray
> cells and the intercellular spaces between ray cells. Vessels have lateral
> wall pitting facing not only to ray cells (cross-field) but also to the
> space. This is the only Sonneratia pneumatophores that have intercellular
> space serving for water conduction in ray tissues among all woody plants
as
> far as we know. As it has fairly specific anatomy in addition to the ray
> intercellular spaces, we will introduce more minutely focusing on the
> pneumatophore secondary xylem structure in this paper.
>
> Key words: anatomy, mangrove, pneumatophore, root system, Sonneratia alba,
> water conduction
>
> After presentation on September 10, we got some arguments from attendants
> including Prof. Pieter Baas. The most important problem is  wether the
> intercellular space is actually filled by water or by air. We are now
> planning further experiments and observations  by employing various
methods
> including cryo-SEM.
>
>
> Mitsuo
>
> --------------------------------------
> Prof. Mitsuo Suzuki
> mitsuos@mail.cc.tohoku.ac.jp
> Director, the Tohoku University Museum, Tohoku University
> Director, Botanical Garden, Graduate School of Science, Tohoku University
> Kawauchi, Aoba, Sendai 980-0862, JAPAN
> TEL&FAX(direct) +81-(0)22-217-6788
> Office of Botanical Garden TEL +81-(0)22-217-6760 FAX +81-(0)22-217-6766
> Secretory (Miss Yagi)  yagi@mail.cc.tohoku.ac.jp  TEL +81-(0)22-217-6761
> ----------------------------------
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