Maize kernels have a triploid endosperm and a diploid embryo. Storage reserves move from the endosperm to the embryo as it grows. Mutants have been identified with abnormal embryos but normal endosperms, although usually a defective endosperm prevents normal embryo formation. Here Zheng and Li et al. investigated how disrupting the accumulation of zein proteins in the endosperm (through RNA interference) affects embryo development. In these plants, the embryo produces more globlulin, another type of storage protein. Transcriptomic analysis showed that many of the genes affected by zein gene silencing are regulated by transcription factor VIVIPAROUS-1 (VP1), so named because loss-of-function of VP1 leads to premature seed germination (vivipary means live birth). In vp1 mutants, nutrient assimilation in the embryo is also abnormal. This study shows a key role for VP1 in signalling and nutrient transfer between the endosperm and embryo. (Summary by Mary Williams) Plant Cell 10.1105/tpc.19.00444.
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