Departamento Biología Animal, Biología Vegetal y Ecología, Universidad de Jaén, Paraje las Lagunillas s/n, 23071, Jaén, Spain.
Department of Biology, Institute for Genome Sciences and Policy, Duke University, PO Box 90338, Durham, NC 27708, USA.
New Phytol. 2012 Feb;193(3):797-805. doi: 10.1111/j.1469-8137.2011.03988.x. Epub 2011 Dec 12.
• The ecological and adaptive significance of plant polyploidization is not well understood and no clear pattern of association between polyploid frequency and environment has emerged. Climatic factors are expected to predict cytotype distribution. However, the relationship among climate, cytotype distribution and variation of abiotic stress tolerance traits has rarely been examined. • Here, we use flow cytometry and root-tip squashes to examine the cytotype distribution in the temperate annual grass Brachypodium distachyon in 57 natural populations distributed across an aridity gradient in the Iberian Peninsula. We further investigate the link between environmental aridity, ploidy, and variation of drought tolerance and drought avoidance (flowering time) traits. • Distribution of diploids (2n = 10) and allotetraploids (2n = 30) in this species is geographically structured throughout its range in the Iberian Peninsula, and is associated with aridity gradients. Importantly, after controlling for geographic and altitudinal effects, the link between aridity and polyploidization occurrence persisted. Water-use efficiency varied between ploidy levels, with tetraploids being more efficient in the use of water than diploids under water-restricted growing conditions. • Our results indicate that aridity is an important predictor of polyploid occurrence in B. distachyon, suggesting a possible adaptive origin of the cytotype segregation.
• 植物多倍体化的生态和适应意义尚未得到很好的理解，也没有出现多倍体频率与环境之间明确的关联模式。气候因素有望预测细胞型分布。然而，气候、细胞型分布和非生物胁迫耐受性性状变异之间的关系很少被研究。• 在这里，我们使用流式细胞术和根尖压片法，在分布于伊比利亚半岛干旱梯度的 57 个自然种群中，研究了温带一年生草本植物短柄草的细胞型分布。我们进一步研究了环境干旱、倍性和耐旱性和耐旱性（开花时间）性状变异之间的联系。• 在该物种的范围内，其分布的二倍体（2n = 10）和异源四倍体（2n = 30）在整个伊比利亚半岛的地理结构上是有组织的，并且与干旱梯度有关。重要的是，在控制了地理和海拔效应后，干旱与多倍体发生之间的联系仍然存在。水分利用效率在不同倍性水平之间存在差异，在水分受限生长条件下，四倍体比二倍体更有效地利用水分。• 我们的结果表明，干旱是短柄草多倍体发生的一个重要预测因子，这表明细胞型分离可能具有适应性起源。
