Calorimetric properties of dehydrating pollen - Analysis of a desiccation-tolerant and an intolerant species
Calorimetric properties of dehydrating pollen - Analysis of a desiccation-tolerant and an intolerant species
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DOI：
10.1104/pp.111.1.235
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发表时间：
1996-05-01
期刊：
影响因子：
7.4
通讯作者：
Leprince, O
中科院分区：
文献类型：
--
作者：
Buitink, J;WaltersVertucci, C;Leprince, O
研究了香蒲（Typha latifolia L.）和玉米花粉的脱水敏感性。研究了使用差示扫描量热法，试图进一步解开复杂的脱水耐受机制。在水含量（wc）值小于0.21（T. latifolia）和0.26（Z.玉米）g H2O/g干重。在水分含量的熔化过渡是不可观察的，水的性质可以通过热容量的变化来表征。三个水化区域可以区分与定义的w值作为温度的函数变化。在这两个物种中观察到类似于二级转变的基线功率的变化，并将其解释为玻璃-液体转变，玻璃化转变温度取决于我们。无论脱水耐性的程度，两个花粉表现出类似的状态图。玉米花粉在室温下的生活力随着未冻水组分的去除而逐渐降低。在玉米中，在谷物充分干燥进入玻璃态之前，活力完全丧失。显然，玻璃态本身不能提供耐干燥性。从现有的数据，我们得出结论，虽然没有重大的差异，在物理行为的水可以区分耐干燥和不耐花粉，生理反应的水分损失之间的两种花粉类型。
The physical state of water in the desiccation-tolerant pollen of Typha latifolia L. and the desiccation-sensitive pollen of Zea mays L. was studied using differential scanning calorimetry in an attempt to further unravel the complex mechanisms of desiccation tolerance. Melting transitions of water were not observed at water content (wc) values less than 0.21 (T. latifolia) and 0.26 (Z. mays)g H2O/g dry weight. At moisture levels at which melting transitions were not observable, water properties could be characterized by changes in heat capacity. Three hydration regions could be distinguished with the defining we values changing as a function of temperature. Shifts in baseline power resembling second-order transitions were observed in both species and were interpreted as glass-to-liquid transitions, the glass-transition temperatures being dependent on we. Irrespective of the extent of desiccation tolerance, both pollens exhibited similar state diagrams. The viability of maize pollen at room temperature decreased gradually with the removal of the unfrozen water fraction. In maize, viability was completely lost before grains were sufficiently dried to enter into a glassy state. Apparently, the glassy state per se cannot provide desiccation tolerance. From the existing data, we conclude that, although no major differences in the physical behavior of water could be distinguished between desiccation-tolerant and -intolerant pollens, the physiological response to the loss of water varies between the two pollen types.