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Title: Nutrient translocation of offspring in plants
Author: Bateman, Perry James Dominic
ISNI:       0000 0004 5366 0475
Awarding Body: University of Warwick
Current Institution: University of Warwick
Date of Award: 2014
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A key question in biology is how the transfer of nutrients from mother to offspring is regulated. In mammals, the translocation of nutrients to the embryo is mediated by the placenta, while in flowering plants is governed by the seed endosperm. Current evidence shows that in plants, nutrient transfer from maternal tissues to developing embryos is regulated at two levels: Initially, from maternal integuments to endosperm through a layer of specialised transfer cells and secondly from endosperm to embryo through the embryo-surrounding cells (ESR). However, a remaining question is: how is the translocation of nutrients between these two layers coordinated? The aim of this work was to investigate small cysteine-rich proteins (CRP) and their involvement in the reproductive development of cereal crops. This was carried out by characterisation of ZmMlp1, a novel plant CRP gene, using promoter reporters, spatiotemporal gene expression profiling, biochemical protein characterisation and localisation. The function of ZmMlp1 was then investigated by knocking down its expression in maize through RNA interference and subsequent morphological and molecular phenotypic characterisation. The 3D structure of ZmMLP1 was resolved by solution state NMR, allowing investigation into key structural components and how they contribute to the functionality of ZmMLP1. The characterisation of ZmMLP1 demonstrated a novel expression pattern in maize, since ZmMLP1 was shown to be a secreted protein expressed in both the central cell of the ovule and the ESR of the developing endosperm between 0 and 10 DAP. Functionally, ZmMLP1 was shown to play a role in embryonic development, demonstrated by a defective embryo patterning phenotype displayed by the RNAi transgenics. Furthermore, seed weight and size was shown to be significantly reduced in ZmMlp1 –RNAi lines, linking ZmMlp1 to crop yield. The structure of ZmMLP1 was shown to contain a knottin-like core, stabilised by 4 disulphide bonds which support disordered sequence loops that form key sections of the molecular surface. Sequence chimeras formed from ZmMLP1 and AtESF1.3 induced a known suspensor phenotype in Arabidopsis, demonstrating that specific structural loops are critical to CRP functionality. Collectively these studies have furthered the understanding of nutrient translocation between maternal tissue to offspring and how CRPs are involved in these plant processes.
Supervisor: Not available Sponsor: Biogemma
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QK Botany