Departamento de Biología y Geología, Área de Biodiversidad y Conservación, Escuela Superior de Ciencias Experimentales y Tecnología, Universidad Rey Juan Carlos, c/Tulipán s/n, Móstoles 28933, Spain.
J Exp Bot. 2013 Aug;64(11):3137-46. doi: 10.1093/jxb/ert147.
Stomata are the major gates regulating substrate availability for photosynthesis and water loss. Although both processes are critical to yield and to resource-use efficiency, we lack a comprehensive picture on how domestication and further breeding have impacted on leaf stomata. To fill this gap, stomatal sizes and densities were screened in cultivated and wild ancestor representatives of a uniquely large group of 24 herbaceous crops. Anatomical data and gas-exchange models were combined to compute maximum potential conductance to water, separately for upper and lower leaf sides. The evolution of maximum conductance under domestication was diverse. Several crops increased, others decreased (noticeably high-conductance species), and others kept a similar potential conductance following domestication. It was found that the contribution of upper leaf sides to maximum conductance was statistically higher in cultivated than in wild ancestors. For crops showing this response, reduced stomatal density in the lower side of domesticated leaves was responsible for the observed 'adaxialization' of conductance. Increases in the size of stomata at the upper epidermis played a comparatively minor role. Nevertheless, this overall response was varied in magnitude and direction, signalling crop-wise specificities. Observed patterns reflect only potential conductances based on anatomical traits and should be used with care until actual physiological outcomes are measured. Together with advancements in the developmental genetics of stomata, our findings might hint at new breeding avenues, focused on stomata distribution. Provided urgent needs for increasing yields, the opportunities of enhancing traits of the physiological relevance of stomata should not be ignored.
气孔是调节光合作用和水分损失底物可用性的主要门户。尽管这两个过程对产量和资源利用效率都至关重要，但我们缺乏关于驯化和进一步选育如何影响叶片气孔的全面认识。为了填补这一空白，对 24 种草本作物这一独特大组的栽培和野生祖先代表进行了气孔大小和密度的筛选。结合解剖学数据和气体交换模型，分别计算了上、下叶面的最大潜在导水率。驯化过程中最大导水率的进化是多样化的。一些作物增加了，另一些减少了（明显的高导水物种），而另一些则在驯化后保持相似的潜在导水率。结果发现，与野生祖先相比，栽培叶片上表皮对最大导水率的贡献具有统计学意义。对于表现出这种反应的作物，驯化后叶片下表皮气孔密度的降低是导致导水率“背腹化”的原因。上表皮气孔大小的增加相对作用较小。然而，这种整体反应在幅度和方向上是不同的，表明了作物特异性。观察到的模式仅反映基于解剖学特征的潜在导水率，在实际生理结果得到测量之前应谨慎使用。随着气孔发育遗传学的进步，我们的发现可能暗示着新的选育途径，重点是气孔的分布。鉴于提高产量的迫切需求，不应忽视增强与气孔生理相关性相关的性状的机会。
