Jáuregui Damelis, Castro Mercedes, Ruiz-Zapata Thirza, Lapp Marlene
Rev Biol Trop. 2014 Dec;62(4):1625-36.
In Venezuela, Atriplex is represented by A. cristata and A. oestophora, the latter being endemic; they inhabit coastal areas with high temperatures, high solar radiation and sandy soils with high salt content. This work aimed to provide information to facilitate and clarify these species taxonomic delimitation, throughout the study of the anatomy of their vegetative organs; this may also clarify our understanding of their adaptability to soil and climatic conditions prevailing in areas they inhabit. The plant material was collected from at least three individuals of each species in Punta Taima Taima and Capatárida, Falcon. Segments of roots, located near the neck and towards the apex, apical, middle and basal internodes of stems, were taken; and of leaves, located in the middle portion of plants. This material was fixed in FAA (formaldehyde, acetic acid, 70% ethanol) until processing. Semipermanent and permanent microscope slides were prepared with transverse or longitudinal sections, made using a razor (free-hand) or a rotation microtome, in this latter case, after paraffin embedding; besides, additional plates were mounted with portions of leaf epidermis, obtained by the maceration technique. The sections were stained with aqueous toluidine blue (1%) or safranin-fast-green, and mounted in water-glycerin or in Canada balsam. In order to calculate the vulnerability index, the vessel diameter in the vascular rings of roots, as well as their density, were quantified. Our results revealed structural features in the different organs, that resulted of taxonomic value and allowed the distinction of the species: in the leaf, the presence of aquifer tissue, the number of vascular bundles and their organization in the midrib, and the collenchyma differentiation in this part of the leaf; in the roots, the xylem and phloem arrangement in the growth rings, the nature of conjunctive tissue, and the presence of included phloem in one species. In addition, the species showed typical anatomical features of halophytes and xerophytes, such as: high density of trichomes on leaves and young stems which act as salt secreting glands, abundant sclerenchyma in stems and roots, water storage tissue and Kranz anatomy in leaves, narrow cortical region in young roots, presence of cambial variants in stems and roots, as well as short and narrow xylem vessels. Vulnerability index calculations indicated that both species tend to assure conduction but not the efficiency of the system. Atriplex species have anatomical characters which facilitate their adaptation to the special conditions prevailing in their habitats and that may be used for taxonomic delimitation.
在委内瑞拉，滨藜属植物有鸡冠滨藜和奥氏滨藜，后者为特有种；它们生长在高温、高太阳辐射且土壤含盐量高的沿海沙地。本研究旨在通过对其营养器官解剖结构的研究，提供有助于明确和澄清这些物种分类界定的信息；这也可能有助于我们理解它们对所栖息地区土壤和气候条件的适应性。植物材料取自法尔孔州塔伊马塔伊马角和卡帕蒂达的每个物种至少三个个体。采集了靠近颈部和根尖的根段、茎的顶端、中部和基部节间，以及植株中部的叶片。这些材料用FAA（甲醛、乙酸、70%乙醇）固定直至处理。制作了半永久和永久显微镜载玻片，用剃须刀（徒手）或旋转切片机制备横切或纵切片，后者是在石蜡包埋后进行；此外，还制作了通过浸解技术获得的叶表皮部分的额外装片。切片用1%的水溶甲苯胺蓝或番红 - 固绿染色，并用甘油水或加拿大树胶封片。为了计算脆弱性指数，对根维管束环中的导管直径及其密度进行了量化。我们的结果揭示了不同器官的结构特征，这些特征具有分类学价值，能够区分这两个物种：在叶片中，有储水组织的存在、维管束的数量及其在中脉中的排列，以及叶片这部分的厚角组织分化；在根中，生长轮中木质部和韧皮部的排列、结合组织的性质，以及一个物种中存在内韧皮部。此外，这些物种表现出盐生植物和旱生植物的典型解剖特征，如：叶片和幼茎上高密度的毛状体，其起到分泌盐分的腺体作用，茎和根中有丰富的厚壁组织，叶片中有储水组织和花环结构，幼根的皮层区域狭窄，茎和根中有形成层变异，以及短而窄的木质部导管。脆弱性指数计算表明，这两个物种都倾向于确保传导，但不保证系统的效率。滨藜属物种具有有助于它们适应其栖息地特殊条件的解剖特征，这些特征可用于分类界定。
