Transcription activator that acts as a positive regulator of male germline development by promoting both gametic cell specification and cell cycle progression (PubMed:15694308, PubMed:15618418, PubMed:19300502, PubMed:21285328). Binds to canonical MYB sites 5'-AACCGTC-3', 5'-AAACCGC-3' and 5'-AACCGT-3' in promoters to trigger the expression of male germline-specific or enriched genes (e.g. MGH3, GEX2 and GCS1), including those required for fertilization (PubMed:21285328, PubMed:19300502). Required for sperm cell specification leading to pollen maturation by activating a germline-specific regulon (PubMed:21285328, PubMed:15694308, PubMed:15618418, PubMed:19300502). Involved in pollen mitosis entry at G2-M transition via the regulation of CYCB1-1, DAZ1 and DAZ2 expression (PubMed:15618418, PubMed:19300502, PubMed:24876252). Accumulates in sperm-cell nuclei. Confined to inflorescences, especially in stamens and pollen. Strict spatial and temporal transcriptional activation leading to a specific expression in the male germline cells; this specific expression pattern is dependent of the regulatory region of DUO1 (ROD1) 5'-YAACYGY-3' in its promoter (PubMed:15694308, PubMed:27624837). First observed in the germ cell during or soon after engulfment by the vegetative cell, just after asymmetric division. In maturating pollen, accumulates in germ cells before mitosis and remains high in mature sperm cells. Expression persists during pollen development (PubMed:19300502). Repressed by the microRNA 159 (miR159); the production of miR159 is stimulated by the anaphase promoting complex/cyclosome (APC/C) (PubMed:21441434). Activated by ARID1 in male germline cells via specific histone acetylation regulation (e.g. H3K9Ac) (PubMed:25057814). Loss of male fertility. Reduced expression of germline-specific genes (e.g. MGH3, GEX2 and GCS1) (PubMed:19300502). Blocked generative cell division resulting in the formation of bicellular pollen grains at anthesis. Pollen fails to enter mitosis at G2-M transition associated with reduced levels of CYCB1-1. Blocked generative cell division followed by endocycle during pollen maturation leads to single larger diploid sperm cell unable to perform fertilization (PubMed:15694308, PubMed:15618418, PubMed:19300502, PubMed:24876252). Enhanced polytubey (e.g. multiple pollen tubes entering ovules) (PubMed:22608506). Truncated N-terminus. Truncated N-terminus.