About this Research Topic
When seeds germinate in the natural habitat, their first major tasks are to safely break through the soil, successfully strip off the seed coat, and prepare for autotrophic growth above the soil surface. To fulfill these tasks, the seedlings form the apical hook first, and then start to elongate the shoot responding to the directions of light and gravity to take its advantageous shape and position. These events have been the target of researchers’ interest since the late 19th century discoveries of the first plant hormone, auxin, as well as the plant photoreceptors, phytochrome and phototropin.
More recently, the introduction of molecular-biological techniques is opening a new aspect of analysis of the mechanisms of such physiological events in germinating seedlings. These events are commonly caused by differences of elongation (differential growth) between the opposite sides of the shoot part involved, and are distinct from the photo- or gravi-tropical growth difference that are solely governed by the direction of the incident light and gravity vector. Apical hook formation is complex, involving an intrinsic property of the embryo plumule that in many species is also affected by the direction of the gravity vector and/or non-directional red or far-red light. In addition, the apical hook is a transient phenomenon necessarily followed by its opening. Thus, the whole behavior of the apical hook still contains many problems to be settled even by pure physiological approaches in addition to up-to-date molecular techniques. The current information on photo- and gravi-tropism of the shoot is expected to greatly contribute not only to clarifying the mechanisms of the apical hook phenomenon, but broadly of the tactics for a seedling to shift to autotrophic life.
In such a view, it will be very productive to bring together and publish collectively as an e-book the new information on the apical hook and other bending phenomena of the shoot. We welcome any type of articles: original researches, methods, reviews, mini-reviews or perspectives. Before being bound as an e-book, each manuscript is first published upon acceptance in the journal, Frontiers in Plant Science (enjoying a high impact factor, 3.637 for 2013), without waiting for all manuscripts being received. The associate editors cordially invite you to participate in the program of this research topic.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.