First off the mark: early seed germination

Abstract

Most plant seeds are dispersed in a dry, mature state. If these seeds are non-dormant and the environmental conditions are favourable, they will pass through the complex process of germination. In this review, recent progress made with state-of-the-art techniques including genome-wide gene expression analyses that provided deeper insight into the early phase of seed germination, which includes imbibition and the subsequent plateau phase of water uptake in which metabolism is reactivated, is summarized. The physiological state of a seed is determined, at least in part, by the stored mRNAs that are translated upon imbibition. Very early upon imbibition massive transcriptome changes occur, which are regulated by ambient temperature, light conditions, and plant hormones. The hormones abscisic acid and gibberellins play a major role in regulating early seed germination. The early germination phase of Arabidopsis thaliana culminates in testa rupture, which is followed by the late germination phase and endosperm rupture. An integrated view on the early phase of seed germination is provided and it is shown that it is characterized by dynamic biomechanical changes together with very early alterations in transcript, protein, and hormone levels that set the stage for the later events. Early seed germination thereby contributes to seed and seedling performance important for plant establishment in the natural and agricultural ecosystem.

Temperature and substrate on Plukenetia volubilis L. seed germination

“…The sharp decrease in the germination percentage of the seeds from 35 ºC on must have been caused by damages to their structure, because high temperatures inhibit embryo development, cause enzymatic alterations and reduce the amount of free amino acids of the synthesis of RNA, modifying the speed of metabolic reactions (Weitbrecht et al, 2011;Borges & Toorop, 2015).…”

“…For the production of seedlings of a certain species, it is important to identify temperatures and substrates that favor their germination and growth (Martins et al, 2012). Temperature acts on the speed of water absorption and biochemical reactions that determine the entire process of germination, and the substrate is also important, because its chemical composition, texture and structure influence the availability of water, oxygen, light and nutrients (Lima et al, 2010;Weitbrecht et al, 2011;Silva et al, 2014).…”

Single-seed oxygen consumption measurements and population-based threshold models link respiration and germination rates under diverse conditions

“…However, P. Bello and K.J. Bradford 216 other data and arguments point to metabolic processes, such as transcriptional changes and enzymatic endosperm weakening, to control the timing of radicle emergence (Nonogaki et al, 2007;Weitbrecht et al, 2011). Regardless, seed respiration is particularly sensitive to Ψ and responds quantitatively to different stress levels, as shown by the close fit of the hydrotime model to respiration data (Fig.…”

Demethylesterification of Cell Wall Pectins in Arabidopsis Plays a Role in Seed Germination

“…Water uptake by germinating seeds can be divided into three phases: phase I is imbibition and is characterized by rapid water uptake by the dry seed; phase II is associated with a lag, during which water uptake slows considerably and several metabolic changes take place (Bewley, 1997a;Weitbrecht et al, 2011). In Arabidopsis and related endospermic species, such as cress (Lepidium sativum) and tobacco, the completion of germination requires testa rupture (part of phase II) followed by endosperm rupture (Liu et al, 2005;Manz et al, 2005;Müller et al, 2006) and radicle elongation.…”