Stop, slow-down or speed-up? : The role of mRNA binding proteins during seed germination

Abstract

The seed life cycle Seed development and maturation: The birth of a seedArabidopsis seed development is composed of two phases, namely, the embryogenesis and the seed maturation phase which partially overlap with each other (Fig. 1.1) (Bewley et al., 2012). The embryogenesis phase, starts with a double fertilization event that leads to a single zygote. This zygotic embryo grows filling the embryo sac through cell division and expansion, and ends with all the embryo structures being formed. At the end of this phase, cell division is arrested (Fig. 1.1A) (Raz et al., 2001). While the embryo is still transforming morphologically, the first part of the maturation phase commences (Raz et al., 2001;Nonogaki, 2019). The maturation phase begins with accumulation of reserves like storage proteins, mRNAs and sugars important for the germination process (Fig. 1.1B). This is followed by an intense period of moisture loss and ends with the embryo being in a quiescent and dry state. In this dehydrated state, desiccation tolerance and primary dormancy have been established (Fig 1 .1C) (Gutierrez et al., 2007;Holdsworth et al., 2008). The mature seed houses an embryo that forms the new plant, a single layer of surrounding tissue often referred to as the endosperm, and the seed coat (testa), a protective outer layer of dead tissue (