Direct evidence on participation of root hairs in phosphorus (32P) uptake from soil
Direct evidence on participation of root hairs in phosphorus (32P) uptake from soil
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DOI：
10.1023/a:1004346412006
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发表时间：
1998-01-01
期刊：
影响因子：
4.9
通讯作者：
Nielsen, NE
中科院分区：
文献类型：
--
作者：
Gahoonia, TS;Nielsen, NE
根毛基本上延伸根表面的离子吸收。尽管许多研究表明植物根毛与磷吸收之间存在着一定的关系，但根毛在植物吸收磷中的作用仍存在争议。我们直接通过根毛测量了土壤中磷的吸收。仅允许根毛穿过粘在PVC管底部的紧密拉伸的尼龙筛网（53 μ m）。在另一个PVC管中填充放射性同位素磷（P）示踪剂P-32（185 kBq g（-1）干土）标记的土壤中，穿透根毛生长2天和4天。将厚度范围为0.25 mm至2.0 mm的透明塑料环插入两个PVC管之间。这为原位显微镜观察提供了狭缝宽度，这证实了只有根毛生长到P-32标记的土壤中。在某些情况下，没有插入环（狭缝宽度= 0），根毛和根表面都与标记的土壤（总P-32吸收）接触。通过测定植物地上部P-32的活性（32 P仅通过根毛吸收）来定量仅通过根毛从土壤中吸收P-32，结果表明，当70%的根毛生长到标记土壤中时，它们占总吸收P-32的63%。随着进入P-32标记土壤的根毛数量的减少，植株地上部中的P-32含量也随之减少。在这项研究中，通过根毛吸收磷的土壤为基础的系统，其中根毛是唯一的途径P-32从土壤到植物地上部。因此，本研究为根毛参与土壤磷素吸收提供了有力的证据。
Root hairs substantially extend root surface for ion uptake. Although many reports suggest a relationship between root hairs and phosphorus (P) uptake of plants, the role of root hairs in phosphorus uptake from soils is still debated. We measured uptake of phosphorus from soil directly via root hairs. Root hairs only were allowed to penetrate through a tightly stretched nylon screen (53 mu m) glued to the bottom of a PVC tube. The penetrating root hairs grew for 2 and 4 days in soil labelled with radioisotope phosphorus (P) tracer P-32 (185 kBq g(-1) dry soil) filled in another PVC tube. Transparent plastic rings of thickness ranging from 0.25 mm to 2.0 mm were inserted between the two PVC tubes. This provided slit width for microscopic observations in situ, which confirmed that only root hairs were growing into the P-32 labelled soil. In some cases no rings were inserted (slit width = 0) where both root hairs and root surface were in contact with the labelled soil (total P-32 uptake). The uptake of P-32 from soil via the root hairs only was quantified by measuring activity of P-32 in the plant shoot ((32)p uptake only via root hairs).The results showed that when 70 percent of the root hairs grew into the labelled soil, they contributed to 63 percent of the total P uptake. With decreasing number of root hairs growing into the P-32 labelled soil, the quantity of P-32 in the plant shoot decreased. In this study, P uptake via root hairs was measured in a soil-based system, where root hairs were the only pathway of P-32 from soil to the plant shoot. Therefore, this study provides a strong evidence on the substantial participation of root hairs in uptake of phosphorus from soil.