Departamento de Microbiologia e Inmunologia, Facultad de Ciencias Exactas Fco-Qcas y Naturles, Universidad Nacional de Rio Cuarto, Ruta Nacional 36 Km 601(5800), Rio Cuarto, Cordoba, Argentina.
Mycologia. 2004 May-Jun;96(3):470-8.
Studies were conducted to determine the effect of osmotic (NaCl, glycerol) and matric (PEG 8000) water stress on temporal germination and growth of two F. graminearum strains over the water potential range of -0.7 to -14.0 MPa at 15 and 25 C. The effect on endogenous water potentials and accumulation of sugars and sugar alcohols also were measured. For both strains, germination occurred rapidly over the same range of osmotic or matric potential of -0.7 to -5.6 MPa after 4-6 h incubation. At lower osmotic and matric potentials (-7.0 to -8.4 MPa), there was a lag of up to 24 h before germination. Optimum germ-tube extension occurred between -0.7 and -1.4 MPa for both strains but varied with the solute used. Growth was optimal at -1.4 MPa and 25 C in response to matric stress, with the minimum being about -8.0 and -11.2 MPa at 15 and 25 C, respectively. In contrast, F. graminearum grew fastest at -0.7 MPa and was more tolerant of solute stress modified with either glycerol or NaCl with a minimum of about -14.0 MPa at 15 and 25 C. A decrease in the osmotic/matric water potential of the media caused a large decrease in the mycelial water potential (Ψ(c)) as measured by thermocouple psychrometry. In general, the concentration of total sugar alcohols in mycelia increased as osmotic and matric potential were reduced to -1.2 MPa. However, this increase was more evident in mycelia from glycerol-amended media. The quality of the major sugar alcohol accumulated depended on the solute used to generate the water stress. The major compounds accumulated were glycerol and arabitol on osmotically modified media and arabitol on matrically modified media. In response to matric stress, the concentration of trehalose in colonies generally was higher in the case of osmotic stress. In each water-stress treatment there was a good correlation between Ψ(c) and total sugar alcohol content.
研究了渗透（NaCl、甘油）和基质（PEG8000）水分胁迫对两个 F. graminearum 菌株在 15 和 25°C 下水势范围为-0.7 至-14.0MPa 时的时间发芽和生长的影响。还测量了对内源水势和糖和糖醇积累的影响。对于两个菌株，在 4-6 小时孵育后，在渗透或基质潜力相同的-0.7 至-5.6MPa 范围内，发芽迅速。在较低的渗透压和基质潜力（-7.0 至-8.4MPa）下，发芽前有长达 24 小时的滞后。对于两个菌株，最佳的芽管延伸发生在-0.7 和-1.4MPa 之间，但随溶质的不同而变化。在基质胁迫下，生长最佳在-1.4MPa 和 25°C，而在 15 和 25°C 下，最低分别约为-8.0 和-11.2MPa。相比之下，F. graminearum 在-0.7MPa 下生长最快，对用甘油或 NaCl 修饰的溶质胁迫更耐受，在 15 和 25°C 下最低约为-14.0MPa。培养基的渗透压/基质水势降低会导致热电偶湿度计测量的菌丝体水势（Ψ（c））大幅降低。一般来说，随着渗透压和基质势降低至-1.2MPa，菌丝体中的总糖醇浓度增加。然而，在添加甘油的培养基中的菌丝体中，这种增加更为明显。积累的主要糖醇的质量取决于用于产生水分胁迫的溶质。在渗透压修饰的培养基上积累的主要化合物是甘油和阿拉伯糖醇，而在基质修饰的培养基上积累的主要化合物是阿拉伯糖醇。在基质胁迫下，在渗透压胁迫的情况下，糖海藻糖在菌落中的浓度通常更高。在每种水分胁迫处理中，Ψ（c）和总糖醇含量之间存在良好的相关性。
