Proteomics reveal tissue‐specific features of the cress (Lepidium sativum L.) endosperm cap proteome and its hormone‐induced changes during seed germination

Abstract

Mature angiosperm seeds consist of an embryo surrounded by the endosperm and the testa. The endosperm cap that covers the radicle plays a regulatory role during germination and is a major target of abscisic acid-induced inhibition of germination. Cress (Lepidium sativum) is a close relative of the model plant Arabidopsis thaliana (Arabidopsis). Cress seeds offer the unique possibility of performing tissue-specific proteomics due to their larger size while benefiting the genomic tools available for Arabidopsis. This work provides the first description of endosperm cap proteomics during seed germination. An analysis of the proteome of the cress endosperm cap at key stages during germination and after radicle protrusion in the presence and absence of abscisic acid led to the identification of 144 proteins, which were clustered by the changes in their abundances and categorized by function. Proteins with a function in energy production, protein stability and stress response were overrepresented among the identified endosperm cap proteins. This strongly suggests that the cress endosperm cap is not a storage tissue as the cereal endosperm but a metabolically very active tissue regulating the rate of radicle protrusion.

Regulation of Seed Germination in the Close Arabidopsis RelativeLepidium sativum: A Global Tissue-Specific Transcript Analysis

“…The abundance of one Asp protease was shown to increase from 8 to 18 h during the period of CAP weakening. The authors concluded that this early mobilization of protein bodies in the cap is likely to serve a nonnutritional function in the control of germination (Mü ller et al, 2010). These observations are consistent with the CAPspecific expression of a number of putative Asp protease transcripts within our data set (Fig.…”

“…Molecular studies of osmoprimed seeds of cauliflower (Brassica oleracea; Fujikura and Karssen, 1995) identified two Asp proteases with enhanced expression upon priming. A proteomic analysis of Lepidium CAP tissue (Mü ller et al, 2010) identified Asp proteases as a main class of proteins involved in storage protein degradation. The abundance of one Asp protease was shown to increase from 8 to 18 h during the period of CAP weakening.…”

OsRACK1 Is Involved in Abscisic Acid- and H2O2-Mediated Signaling to Regulate Seed Germination in Rice (Oryza sativa, L.)

“…Although ROS are long considered as hazardous molecules, many recent studies have provided physiological and genetic evidence that ROS may also function as messengers or transmitters of environmental cues during seed germination. There are many reports indicated that seed germination and ROS accumulation appear to be linked, and that seed germination success may be closely associated with internal ROS contents and the activities of ROS-scavenging systems in species such as Arabidopsis thaliana [21],[49], sunflower [22], wheat [50], cress [51] and barley [12], soybean [20], rice [24]. Our results present here suggest that OsRACK1A may also regulate seed germination by mediating ROS production in imbibed seeds.…”

Using proteomics to study sexual reproduction in angiosperms

“…In contrast to most ''shotgun'' proteomic analyses of seeds, Müller et al (2010) reported the results from analysis of a specific tissue, the endosperm cap, during germination of Lepisium sativum seeds. The cap is a specific part of the endosperm surrounding the embryo radicle.…”