Moore P H, Cosgrove D J
U.S. Department of Agriculture, Agricultural Research Service, Aiea, Hawaii 96701, USA.
Plant Physiol. 1991;96(3):794-801. doi: 10.1104/pp.96.3.794.
The osmotic pressure of the cell sap of stalk storage parenchyma of sugarcane (Saccharum spp. hybrids) increases by an order of magnitude during ontogeny to reach molar concentrations of sucrose at maturity. Stalk parenchyma cells must either experience very high turgor at maturation or have an ability to regulate turgor. We tested this hypothesis by using pressure probe techniques to quantify parameters of cell and tissue water relations of sugarcane storage parenchyma during ontogeny. The largest developmental change was in the volumetric elastic modulus, which increased from 6 bars in immature tissue to 43 bars in mature tissue. Turgor was maintained relatively low during sucrose accumulation by the partitioning of solutes between the cell and wall compartments. Membrane hydraulic conductivity decreased from about 12 x 10(-7) centimeters per second per bar down to 4.4 x 10(-7) centimeters per second per bar. The 2.7-fold decrease in membrane hydraulic conductivity during tissue maturation was accompanied by a 7.8-fold increase in wall elasticity. Integration of the cell wall and membrane properties appears to be by the opposing effects of turgor on hydraulic conductivity and elastic modulus. The changes in these properties during development of sugarcane stalk tissue may be a way for parenchyma cells to develop a capacity for expansive growth and still serve as a strong sink for storing high concentrations of sucrose.
甘蔗（甘蔗属杂交种）茎贮藏薄壁细胞的细胞液渗透压在个体发育过程中增加了一个数量级，在成熟时达到蔗糖的摩尔浓度。茎薄壁细胞在成熟时要么经历非常高的膨压，要么具有调节膨压的能力。我们通过使用压力探针技术来量化甘蔗贮藏薄壁细胞在个体发育过程中细胞和组织水分关系的参数，对这一假设进行了测试。最大的发育变化是体积弹性模量，从未成熟组织中的6巴增加到成熟组织中的43巴。在蔗糖积累过程中，通过溶质在细胞和细胞壁区室之间的分配，膨压保持相对较低。膜水力传导率从约每秒每巴12×10⁻⁷厘米下降到每秒每巴4.4×10⁻⁷厘米。组织成熟过程中膜水力传导率下降2.7倍，同时细胞壁弹性增加7.8倍。细胞壁和膜特性的整合似乎是通过膨压对水力传导率和弹性模量的相反作用实现的。甘蔗茎组织发育过程中这些特性的变化可能是薄壁细胞发展出膨胀生长能力并仍然作为储存高浓度蔗糖的强大库的一种方式。
