Department of Biology, University of Washington, Seattle, WA 98195, USA.
J Plant Res. 2010 May;123(3):275-80. doi: 10.1007/s10265-010-0330-9. Epub 2010 Mar 25.
Stomata are an essential land plant innovation whose patterning and density are under genetic and environmental control. Recently, several putative ligands have been discovered that influence stomatal density, and they all belong to the epidermal patterning factor-like family of secreted cysteine-rich peptides. Two of these putative ligands, EPF1 and EPF2, are expressed exclusively in the stomatal lineage cells and negatively regulate stomatal density. A third, EPFL6 or CHALLAH, is also a negative regulator of density, but is expressed subepidermally in the hypocotyl. A fourth, EPFL9 or STOMAGEN, is expressed in the mesophyll tissues and is a positive regulator of density. Genetic evidence suggests that these ligands may compete for the same receptor complex. Proper stomatal patterning is likely to be an intricate process involving ligand competition, regional specificity, and communication between tissue layers. EPFL-family genes exist in the moss Physcomitrella patens, the lycophyte Selaginella moellendorffii, and rice, Oryza sativa, and their sequence analysis yields several genes some of which are related to EPF1, EPF2, EPFL6, and EPFL9. Presence of these EPFL family members in the basal land plants suggests an exciting hypothesis that the genetic components for stomatal patterning originated early in land plant evolution.
气孔是陆地植物的一项基本创新，其模式和密度受遗传和环境控制。最近，发现了几种假定的配体，它们都属于表皮模式因子样家族的分泌富含半胱氨酸的肽，这些配体影响气孔密度。其中两种假定的配体 EPF1 和 EPF2 仅在气孔谱系细胞中表达，负调控气孔密度。第三种，EPFL6 或 CHALLAH，也是密度的负调节剂，但在子叶中表皮下表达。第四种，EPFL9 或 STOMAGEN，在叶肉组织中表达，是密度的正调节剂。遗传证据表明，这些配体可能竞争相同的受体复合物。适当的气孔模式可能是一个复杂的过程，涉及配体竞争、区域特异性和组织层之间的通讯。EPFL 家族基因存在于苔藓植物Physcomitrella patens、石松植物Selaginella moellendorffii 和水稻 Oryza sativa 中，它们的序列分析产生了几个基因，其中一些与 EPF1、EPF2、EPFL6 和 EPFL9 有关。这些 EPFL 家族成员在基础陆地植物中的存在提出了一个令人兴奋的假设，即气孔模式形成的遗传成分在陆地植物进化的早期就已经存在了。
