Xyloglucan remodelling enzymes and the mechanics of plant seed and fruit biology

The developmental transition from flowers to the mature diaspores (seeds or fruits) depends on cell growth and differentiation (Balanza et al., 2016; Finch-Savage and Leubner-Metzger, 2006). The plant cell wall is a dynamic nanoscale network for which the classical model and role of xyloglucan-cellulose tethers in wall structure and cell growth was challenged by recent results from genetics, biomechanics and advanced imaging (Cosgrove, 2018; Moulia, 2013; Zhang et al., 2021a). Xyloglucan (XyG), the predominant hemicellulose, is composed of a a-1,4-glucan backbone that is consecutively substituted with a-1,6-linked xylosyl residues (Frankova and Fry, 2013; Pauly and Keegstra, 2016). Di Marzo et al. (2021) demonstrated that the MADS-box transcription factor SEEDSTICK (STK) specifically controls seed and fruit biology by a-xylosidase (aXYL) mediated XyG-remodelling.