Crop Science Department, Hawaiian Sugar Planters' Association, P.O. Box 1057, Aiea, Hawaii 96701-1057.
Plant Physiol. 1990 Jul;93(3):1147-53. doi: 10.1104/pp.93.3.1147.
Previous studies have suggested that the apoplast solution of sugarcane stalk tissue contains high concentrations of sucrose, but the accuracy of these reports has been questioned because sucrose leakage from damaged cells may have influenced the results. In this study, the solute potential of the apoplast and symplast of the second (immature), tenth, twentieth, thirtieth, and fortieth internodes of field-grown sugarcane (Saccharum spp. hybrid) stalk tissue was determined by two independent methods. Solute potential of the apoplast was measured either directly by osmometry from solution collected by centrifugation, or inferred from the initial water potential of fully hydrated tissue determined by thermocouple psychrometry before the tissue was progressively dehydrated for generation of water potential isotherms. Both methods produced nearly identical values ranging from -0.6 to -1.8 megapascals for immature and mature tissue, respectively. The solute potential of the symplast determined by either method ranged from -1.0 to approximately -2.2 megapascals for immature and mature internodes, respectively. Solute quantitation by HPLC agreed with concentrations inferred from osmometry. Washing thirtieth internode tissue in deionized water increased pressure potential from 0.29 to 1.96 megapascals. The apoplast of mature sugarcane stalk tissue is a significant storage compartment for sucrose containing as much as 25% of the total tissue water volume and as much as 21% of the stored sucrose.
先前的研究表明，甘蔗茎组织的质外体溶液中含有高浓度的蔗糖，但这些报告的准确性受到了质疑，因为受损细胞中的蔗糖渗漏可能影响了结果。在这项研究中，通过两种独立的方法测定了田间生长的甘蔗（甘蔗杂种）茎组织的第二个（未成熟）、第十个、第二十个、第三十个和第四十个节间的质外体和共质体的溶质势。通过离心收集的溶液直接用渗透压计测量质外体的溶质势，或者在组织逐渐脱水生成水势等温线之前，用热电偶湿度计测定充分水合组织的初始水势来推断质外体的溶质势。这两种方法都产生了几乎相同的数值，未成熟和成熟组织的范围分别为-0.6 到-1.8 兆帕。通过任何一种方法测定的共质体溶质势，未成熟和成熟节间的范围分别为-1.0 到约-2.2 兆帕。高效液相色谱法的溶质定量与渗透压计推断的浓度一致。用去离子水洗涤第三十个节间组织可将压力势从 0.29 增加到 1.96 兆帕。成熟甘蔗茎组织的质外体是蔗糖的一个重要储存室，其储存的蔗糖量相当于总组织水量的 25%，相当于储存蔗糖的 21%。
