Storey R., Schachtman D. P., Thomas M. R.
CSIRO Plant Industry -Horticulture Unit, PMB, Merbein, Victoria 3505, Australia and PO Box 350, Glen Osmond, South Australia 5064, Australia.
Plant Cell Environ. 2003 Jun;26(6):789-800. doi: 10.1046/j.1365-3040.2003.01005.x.
X-ray microanalysis was used to study the patterns of K+, Na+ and Cl- accumulation in salinized (25 mm NaCl) and non-salinized grapevine (Vitis) roots. The aim was to determine whether NaCl affects patterns of Cl- accumulation differentially in the roots of a Cl--excluding genotype and a non-excluding genotype. Two regions of fibrous roots were analysed: (1) a region 2-3 mm basipetal to the root tip; and (2) a region of the root 10-12 mm basipetal to the root tip where the outermost layer is the hypodermis. The ion contents of the hypodermis, cortex, endodermis and pericycle vacuoles were analysed. Data were also collected from the cytoplasm of the endodermal and pericycle cells. The analyses showed that the ion profiles of the hypodermis and the endodermis were significantly different from those of the cortex and pericycle. The hypodermis and endodermis had higher K+ and lower Na+ and Cl- than surrounding cells. Some changes due to salinity such as increased K+ concentrations in the hypodermis were also noted. Chloride concentrations did not differ between the genotypes in the hypodermis, across the cortex or in the endodermis, but were higher in the pericycle of the excluder in comparison with the non-excluding genotype. However, K+/Na+ ratios of the cortex and endodermis were higher in the excluder. The pericycle cells exhibited the greatest ability to sequester Na+ and Cl- in vacuoles. Overall the data show cell-type-specific ion accumulation patterns and small but significant differences were found between genotypes. The possibility that these accumulation patterns arise from differences in uptake properties of cell types and/or result from the spatial distribution of the cell types along the competing symplastic and apoplastic ion transport pathways across the root is discussed.
采用X射线微分析法研究了盐渍化（25 mM NaCl）和非盐渍化葡萄（葡萄属）根系中K⁺、Na⁺和Cl⁻的积累模式。目的是确定NaCl是否对Cl⁻排斥型基因型和非排斥型基因型根系中Cl⁻的积累模式有不同影响。分析了须根的两个区域：（1）根尖向基部2 - 3 mm的区域；（2）根尖向基部10 - 12 mm的区域，该区域最外层为下皮层。分析了下皮层、皮层、内皮层和中柱鞘细胞液泡中的离子含量。还收集了内皮层和中柱鞘细胞细胞质的数据。分析表明，下皮层和内皮层的离子分布与皮层和中柱鞘的显著不同。下皮层和内皮层的K⁺含量高于周围细胞，而Na⁺和Cl⁻含量较低。还注意到一些盐度引起的变化，如下皮层中K⁺浓度增加。在下皮层、整个皮层或内皮层中，两种基因型的Cl⁻浓度没有差异，但与非排斥型基因型相比，排斥型基因型的中柱鞘中Cl⁻浓度更高。然而，排斥型基因型皮层和内皮层的K⁺/Na⁺比值更高。中柱鞘细胞在液泡中隔离Na⁺和Cl⁻的能力最强。总体而言，数据显示了细胞类型特异性的离子积累模式，并且在基因型之间发现了微小但显著的差异。讨论了这些积累模式是由细胞类型吸收特性的差异引起的，还是由细胞类型沿着根系中竞争性共质体和质外体离子运输途径的空间分布导致的可能性。
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