Pereyra-Irujo Gustavo A, Velázquez Luciano, Lechner Leandra, Aguirrezábal Luis A N
Unidad Integrada Balcarce, Facultad de Ciencias Agrarias, Universidad Nacional de Mar del Plata, Instituto Nacional de Tecnología Agropecuaria, CC 276, 7620 Balcarce, Argentina.
J Exp Bot. 2008;59(8):2221-32. doi: 10.1093/jxb/ern087. Epub 2008 Apr 29.
Plants under water deficit reduce leaf growth, thereby reducing transpiration rate at the expense of reduced photosynthesis. The objective of this work was to analyse the response of leaf growth to water deficit in several sunflower genotypes in order to identify and quantitatively describe sources of genetic variability for this trait that could be used to develop crop varieties adapted to specific scenarios. The genetic variability of the response of leaf growth to water deficit was assessed among 18 sunflower (Helianthus annuus L.) inbred lines representing a broad range of genetic diversity. Plants were subjected to long-term, constant-level, water-deficit treatments, and the response to water deficit quantified by means of growth models at cell-, leaf-, and plant-scale. Significant variation among lines was found for the response of leaf expansion rate and of leaf growth duration, with an equal contribution of these responses to the variability in the reduction of leaf area. Increased leaf growth duration under water deficit is usually suggested to be caused by changes in the activity of cell-wall enzymes, but the present results suggest that the duration of epidermal cell division plays a key role in this response. Intrinsic genotypic responses of rate and duration at a cellular scale were linked to genotypic differences in whole-plant leaf area profile to water deficit. The results suggest that rate and duration responses are the result of different physiological mechanisms, and therefore capable of being combined to increase the variability in leaf area response to water deficit.
水分亏缺条件下的植物会减少叶片生长，从而降低蒸腾速率，但代价是光合作用减弱。这项工作的目的是分析几种向日葵基因型的叶片生长对水分亏缺的响应，以便识别和定量描述该性状的遗传变异来源，从而用于培育适应特定环境的作物品种。在代表广泛遗传多样性的18个向日葵（Helianthus annuus L.）自交系中评估了叶片生长对水分亏缺响应的遗传变异。对植株进行长期、恒定水平的水分亏缺处理，并通过细胞、叶片和植株尺度的生长模型对水分亏缺响应进行量化。发现各品系在叶片扩展速率和叶片生长持续时间的响应方面存在显著差异，这些响应在叶片面积减少的变异中贡献相同。水分亏缺条件下叶片生长持续时间增加通常被认为是由细胞壁酶活性变化引起的，但目前的结果表明表皮细胞分裂持续时间在这种响应中起关键作用。细胞尺度上速率和持续时间的内在基因型响应与整株植物叶片面积对水分亏缺的基因型差异相关。结果表明，速率和持续时间响应是不同生理机制的结果，因此能够结合起来增加叶片面积对水分亏缺响应的变异性。
