Purnobasuki Hery, Suzuki Mitsuo
Botanical Garden, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-0862, Japan.
J Plant Res. 2004 Dec;117(6):465-72. doi: 10.1007/s10265-004-0181-3. Epub 2004 Nov 5.
Aerenchyma gas spaces are important for plants that grow in flooded and anaerobic sites or habitats, because these gas spaces provide an internal pathway for oxygen transport. The objective of this study is to characterize the development of aerenchyma gas spaces and observe the porosity in roots of Sonneratia alba. Tissue at different developmental stages was collected from four root types, i.e. cable root, pneumatophore, feeding root and anchor root, of S. alba. In S. alba, gas space is schizogenously produced in all root types, and increases in volume from the root meristem to mature root tissues. The aerenchyma formation takes place immediately, or 3-5 mm behind the root apex. At first, cortical cells are relatively round in cross sections (near the root apex); they then become two kinds of cells, rounded and armed, which combine together, forming intercellular spaces behind the root apex. The average dimensions of cortical cells increased more than 1.3 times in the vertical direction and over 3.3 times in the horizontal direction. At maturity, aerenchyma gas spaces are long tuberous structures without diaphragms and with numerous small pores on the lateral walls. Within the aerenchyma, many sclereids grow intrusively. Root porosity in all root types ranged from 0-60%. Pneumatophores and cable roots had the highest aerenchyma area (50-60%).
通气组织气腔对于生长在水淹和厌氧环境或栖息地的植物很重要，因为这些气腔为氧气运输提供了一条内部通道。本研究的目的是描述海桑通气组织气腔的发育过程，并观察其根的孔隙率。从海桑的四种根型，即缆状根、呼吸根、吸收根和固着根中收集不同发育阶段的组织。在海桑中，所有根型的气腔均通过裂生方式产生，且从根尖分生组织到成熟根组织体积逐渐增大。通气组织的形成在根尖处或根尖后方3 - 5毫米处立即开始。起初，皮层细胞在横切面上相对呈圆形（靠近根尖）；随后它们变成两种细胞，圆形细胞和具臂细胞，这两种细胞结合在一起，在根尖后方形成细胞间隙。皮层细胞的平均尺寸在垂直方向上增加了1.3倍以上，在水平方向上增加了3.3倍以上。成熟时，通气组织气腔为长形块状结构，无隔膜，侧壁上有许多小孔。在通气组织内，许多石细胞侵入生长。所有根型的根孔隙率在0 - 60%之间。呼吸根和缆状根的通气组织面积最大（50 - 60%）。
