The male germline of flowering plants is a simple lineage of two cell types: generative\ud(germ) cell and sperm cells. An asymmetric division of the microspore during pollen\ud(male gametophyte) development produces the germ cell, which goes on to divide to\udform a pair of sperm that later fuse with egg and central cells at double fertilisation.\udThe production of functional sperm cells depends upon cell cycle progression and cell\udspecification, and three regulatory proteins – the MYB transcription factor DUO1, and\udthe C2H2 zinc finger proteins DAZ1 and DAZ2 - acting in a gene network have been\udidentified in Arabidopsis to be essential for both of these processes. Expression of\udDAZ1/DAZ2 is triggered by DUO1, and DAZ1/DAZ2 show functional redundancy.\udUnderstanding the mechanisms by which DAZ1 and DAZ2 control male germline\uddevelopment was a major aim of this thesis.\udThe first objective was to explore sequence diversity among DAZ1/DAZ2 flowering\udplant homologues. This study established that the number of zinc finger domains\uddiffered between species, and mutating the zinc finger domains of DAZ1 had different\udeffects on DAZ1 function. Functional analysis of DAZ1 EAR motifs showed that these\udsequences are important for in planta activity. DAZ1 and DAZ2 interact with the\udtranscriptional co-repressor TPL, and a second objective was to investigate the spatiotemporal\udexpression pattern of TPL and its family members in pollen, with male\udgermline expression was observed for TPL and TPR2. The final objective was to\udidentify genes under the regulation of DAZ1/DAZ2. While DAZ1 was predicted to be a\udtranscriptional repressor, through transcriptomics it was revealed that a broad suite of\udgenes were positively regulated by DAZ1, overlapping with targets of DUO1. The\udfindings communicated in this thesis provide new insights into the molecular\udmechanisms controlling male germline development.
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