Key Laboratory of Arid and Grassland Ecology, School of Life Sciences, Lanzhou University, Lanzhou 730000, Gansu, China.
New Phytol. 2010 Jan;185(1):204-16. doi: 10.1111/j.1469-8137.2009.03037.x. Epub 2009 Oct 5.
The homoploid hybrid species Pinus densata is restricted to alpine habitats that exceed the altitude range of its two parental species, Pinus tabulaeformis and Pinus yunnanensis. Alpine habitats usually generate cold-induced water stress in plants. To understand the ecological differentiation between these three species, we examined their physiological responses to drought stress. Potted seedlings of three species were subjected to low, mild, moderate and severe water stress in an automatic-controlled glasshouse. Fifteen indicators of fitness were measured for each species in each treatment, and most of these decreased as drought increased. Pinus densata exhibited higher fitness than both parental species in terms of total dry mass production (TDM) and long-term water use efficiency (WUE(L)) across all treatments; several other ecophysiological traits were also extreme but not across every treatment, and not always in the highest stress treatment. These results indicate that extreme characters that have become well fixed in P. densata, confer a faster seedling growth rate and more efficient water use, which in turn should confer increased drought tolerance. These traits of P. densata likely promoted its ecological separation from its parental species and facilitated its successful colonization and establishment in high-altitude habitats.
同源多倍体杂交种云南松是限制在高山生境超过其两个亲本种，华山松和云南松的海拔范围。高山生境通常在植物中产生冷诱导的水分胁迫。为了了解这三个物种之间的生态分化，我们研究了它们对干旱胁迫的生理响应。在自动控制的玻璃温室中，对三个物种的盆栽幼苗进行低、温和中度以及严重水分胁迫处理。在每个处理中，测量了每个物种的 15 个适应度指标，随着干旱的增加，大多数指标都下降了。云南松在所有处理中，在总干物质生产（TDM）和长期水分利用效率（WUE（L））方面均表现出比双亲种更高的适应性；其他一些生理生态特征也很极端，但并非在每个处理中都如此，也不总是在最高胁迫处理中。这些结果表明，在云南松中已很好固定的极端特征赋予了幼苗更快的生长速度和更有效的水分利用，这反过来又应该赋予其更高的耐旱性。云南松的这些特征可能促进了它与其亲本种的生态分离，并促进了它在高海拔生境中的成功定居和建立。
