Apoplasmic barriers and oxygen transport properties of hypodermal cell walls in roots from four Amazonian tree species
Apoplasmic barriers and oxygen transport properties of hypodermal cell walls in roots from four Amazonian tree species
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DOI：
10.1104/pp.102.014902
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发表时间：
2003-05-01
期刊：
影响因子：
7.4
通讯作者：
Schmidt, W
中科院分区：
文献类型：
--
作者：
De Simone, O;Haase, K;Schmidt, W
外皮中木木化和木质化屏障的形成被认为是一系列适应淹没或浸水条件的一部分，调节溶质和气体进出根部的运输。在这项研究中，分析了栖息地长期遭受洪水侵袭的四种亚马逊树种的皮下细胞壁质外屏障的组成以及根部和周围介质中的氧气分布。在落叶树 Crateva Benthami 的皮下细胞壁中，木栓化作用非常弱，并且以一元酸、2-羟基酸和 omega-羟基羧酸为主。该物种没有表现出任何对洪水的形态适应，并以休眠状态克服了水生期。 Tabernaemontana juruana 是一种能够在水生阶段维持其叶系统的树，其特征是壁广泛木栓化，主要由不饱和 C-18 omega-羟基羧酸和 α,omega-二羧酸类似物（称为典型的木栓质标记）覆盖。另外两种常绿物种，Laetia corymbulosa 和 Salix martiana，其外皮中的脂肪族木栓质含量要少 3 至 4 倍，但超过 85% 的木栓质芳香部分由对羟基苯甲酸组成，这表明木栓质具有防御病原体的功能。没有观察到物种间木质素含量的重大差异。对四个物种根部和根际氧分布的测定表明，木栓化屏障的形成可以有效地限制氧的径向损失，但不能通过外皮细胞壁的木质化来限制。
The formation of suberized and lignified barriers in the exodermis is suggested to be part of a suite of adaptations to flooded or waterlogged conditions, adjusting transport of solutes and gases in and out of roots. In this study, the composition of apoplasmic barriers in hypodermal cell walls and oxygen profiles in roots and the surrounding medium of four Amazon tree species that are subjected to long-term flooding at their habitat was analyzed. In hypodermal cell walls of the deciduous tree Crateva benthami, suberization is very weak and dominated by monoacids, 2-hydroxy acids, and omega-hydroxycarboxylic acids. This species does not show any morphological adaptations to flooding and overcomes the aquatic period in a dormant state. Hypodermal cells of Tabernaemontana juruana, a tree which is able to maintain its leaf system during the aquatic phase, are characterized by extensively suberized walls, incrusted mainly by the unsaturated C-18 omega-hydroxycarboxylic acid and the alpha,omega-dicarboxylic acid analogon, known as typical suberin markers. Two other evergreen species, Laetia corymbulosa and Salix martiana, contained 3- to 4-fold less aliphatic suberin in the exodermis, but more than 85% of the aromatic moiety of suberin are composed of para-hydroxybenzoic acid, suggesting a function of suberin in pathogen defense. No major differences in the lignin content among the species were observed. Determination of oxygen distribution in the roots and rhizosphere of the four species revealed that radial loss of oxygen can be effectively restricted by the formation of suberized barriers but not by lignification of exodermal cell walls.