Chen Xin, Huber Heidrun, de Kroon Hans, Peeters Anton J M, Poorter Hendrik, Voesenek Laurentius A C J, Visser Eric J W
Department of Experimental Plant Ecology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
Ann Bot. 2009 Nov;104(6):1057-67. doi: 10.1093/aob/mcp198. Epub 2009 Aug 16.
Intraspecific variation in flooding tolerance is the basic pre-condition for adaptive flooding tolerance to evolve, and flooding-induced shoot elongation is an important trait that enables plants to survive shallow, prolonged flooding. Here an investigation was conducted to determine to what extent variation in flooding-induced leaf elongation exists among and within populations of the wetland species Rumex palustris, and whether the magnitude of elongation can be linked to habitat characteristics.
Offspring of eight genotypes collected in each of 12 populations from different sites (ranging from river mudflats with dynamic flooding regimes to areas with stagnant water) were submerged, and petioles, laminas and roots were harvested separately to measure traits related to elongation and plant growth.
We found strong elongation of petioles upon submergence, and both among- and within-population variation in this trait, not only in final length, but also in the timing of the elongation response. However, the variation in elongation responses could not be linked to habitat type.
Spatio-temporal variation in the duration and depth of flooding in combination with a presumably weak selection against flooding-induced elongation may have contributed to the maintenance of large genetic variation in flooding-related traits among and within populations.
耐淹性的种内变异是适应性耐淹性进化的基本前提条件，而淹水诱导的茎伸长是使植物能够在浅层、长期淹水条件下存活的重要性状。本研究旨在确定湿地物种酸模叶蓼种群间及种群内淹水诱导的叶片伸长变异程度，以及伸长幅度是否与栖息地特征相关。
从不同地点（从具有动态淹水模式的河滩到积水区域）的12个种群中各收集8种基因型的后代进行淹水处理，分别收获叶柄、叶片和根，以测量与伸长及植物生长相关的性状。
我们发现淹水后叶柄强烈伸长，该性状在种群间和种群内均存在变异，不仅在最终长度上，而且在伸长反应的时间上。然而，伸长反应的变异与栖息地类型无关。
淹水持续时间和深度的时空变异，以及对淹水诱导伸长可能较弱的选择作用，可能有助于维持种群间和种群内与淹水相关性状的大量遗传变异。
