Seed germination is a complex process in which the embryo, enclosed within the surrounding tissues, must quickly switch from a maturation program to a germination‐driven developmental process that will prepare the embryo for seedling growth and establishment. The germination process initiates with water uptake by the dry seed and culminates, usually, with the radicle protrusion. The radicle emergence from the seed is a highly regulated process that involves discrete and coordinated changes in plant cell wall extensibility and rearrangements of its components, among other processes. In this chapter we will review current knowledge of the physiological process of controlled cell separation and expansion, which give the primary cell wall its plastic properties by “loosening” of the main components of the cell wall during seed germination. We will focus on the physiological importance of primary cell wall constitution and modification by the activity in muro of a broad variety of cell wall‐modifying enzymes that include hydrolases and transglycosylases, as well as non‐enzymatic processes such as expansin‐mediated loosening during seed germination.
Part of the book: New Challenges in Seed Biology