Cellular Plasticity in Response to Suppression of Storage Proteins in the <i>Brassica napus</i> Embryo
Hardy Rolletschek, Jörg Schwender, Christina König, Kent D. Chapman, Trevor B. Romsdahl, Christin Lorenz, Hans‐Peter Braun, Peter Denolf, Katrien Van Audenhove, E. Muñz, Nicolas Heinzel, Stefan Ortleb, Twan Rutten, S. McCorkle, Taras Borysyuk, André Guendel, Hai Shi, Michiel Vander Auwermeulen, Stéphane Bourot, Ljudmilla Borisjuk
Abstract
) by analyzing the effect of suppressing key genes encoding protein storage products (napin and cruciferin). The phenotypic outcomes were assessed using NMR and mass spectrometry imaging, microscopy, transcriptomics, proteomics, metabolomics, lipidomics, immunological assays, and flux balance analysis. Surprisingly, the profile of storage products was only moderately changed in RNA interference transgenics. However, embryonic cells had undergone remarkable architectural rearrangements. The suppression of storage proteins led to the elaboration of membrane stacks enriched with oleosin (sixfold higher protein abundance) and novel endoplasmic reticulum morphology. Protein rebalancing and amino acid metabolism were focal points of the metabolic adjustments to maintain embryonic carbon/nitrogen homeostasis. Flux balance analysis indicated a rather minor additional demand for cofactors (ATP and NADPH). Thus, cellular plasticity in seeds protects against perturbations to its storage capabilities and, hence, contributes materially to homeostasis. This study provides mechanistic insights into the intriguing link between lipid and protein storage, which have implications for biotechnological strategies directed at improving oilseed crops.