Vidal Tiphaine, Aissaoui Hafssa, Rehali Sabrina, Andrieu Bruno
UMR ECOSYS, INRAE, AgroParisTech, Université Paris-Saclay, Thiverval-Grignon, France.
AoB Plants. 2021 Jan 4;13(1):plaa072. doi: 10.1093/aobpla/plaa072. eCollection 2021 Feb.
Simulating leaf development from initiation to maturity opens new possibilities to model plant-environment interactions and the plasticity of plant architecture. This study analyses the dynamics of leaf production and extension along a maize () shoot to assess important modelling choices. Maize plants from two cultivars originating from the same inbred line, yet differing in the length of mature leaves were used in this study. We characterized the dynamics of the blade and sheath lengths of all phytomers by dissecting plants every 2-3 days. We analysed how differences in leaf size were built up and we examined the coordination between the emergence of organs and phases of their extension. Leaf extension rates were higher in the cultivar with longer leaves than in the cultivar with shorter leaves; no differences were found in other aspects. We found that (i) first post-embryonic leaves were initiated at a markedly higher rate than upper leaves; (ii) below ear position, sheaths were initiated at a time intermediate between tip emergence and appearance, while above the ear position, sheaths were initiated at a high rate, such that the time interval between the blade and sheath initiations decreased for these leaves; and (iii) ear position also marked a change in the correlation in size between successive phytomers with little correlation of size between upper and lower leaves. Our results identified leaf extension rate as the reason for the difference in size between the two cultivars. The two cultivars shared the same pattern for the timing of initiation events, which was more complex than previously thought. The differences described here may explain some inaccuracies reported in functional-structural plant models. We speculate that genotypic variation in behaviour for leaf and sheath initiation exists, which has been little documented in former studies.
模拟叶片从起始到成熟的发育过程为建模植物 - 环境相互作用以及植物结构的可塑性开辟了新的可能性。本研究分析了玉米茎上叶片产生和伸展的动态过程，以评估重要的建模选择。本研究使用了来自同一自交系的两个品种的玉米植株，但其成熟叶片长度不同。我们通过每2 - 3天解剖植株来表征所有叶元的叶片和叶鞘长度的动态变化。我们分析了叶片大小差异是如何形成的，并研究了器官出现与其伸展阶段之间的协调性。叶片较长的品种的叶片伸展速率高于叶片较短的品种；在其他方面未发现差异。我们发现：（i）胚后第一片叶的起始速率明显高于上部叶片；（ii）在穗位以下，叶鞘在叶尖出现和叶鞘出现之间的中间时间起始，而在穗位以上，叶鞘起始速率较高，使得这些叶片的叶片和叶鞘起始之间的时间间隔缩短；（iii）穗位还标志着连续叶元之间大小相关性的变化，上部和下部叶片之间大小相关性很小。我们的结果确定叶片伸展速率是两个品种之间大小差异的原因。两个品种在起始事件的时间安排上具有相同的模式，这比以前认为的更为复杂。这里描述的差异可能解释了功能 - 结构植物模型中报道的一些不准确之处。我们推测在叶片和叶鞘起始行为上存在基因型变异，而以前的研究对此记录很少。
