DUO1 Activated Zinc Finger (AtDAZ) protein role in the generative cell body morphogenesis

Arabidopsis MYB transcription factor, AtDUO1 regulates generative cell body (GC) morphogenesis from round to semi and fully elongated forms before pollen mitosis-II (PM II). It was hypothesised that DUO1 might regulate morphogenesis through any of its direct target genes or components of the DUO1-DAZ1 network. The developmental analysis of plants harbouring T-DNA insertions in some DUO1 target genes using light and fluorescence microscopy revealed abnormal GC morphogenesis only in daz1 and daz2, but gcs1, trm16, mapkkk10, mapkkk20, tet11, and tip1 all undergo normal elongation indicating that these target genes have no important roles in morphogenesis or may be redundant. The important regulatory role of DUO1 was confirmed through the observed incomplete rescue of morphogenesis of mutant duo1-1 GCs by DAZ1 and independently by a C-terminally deleted version of DUO1 (DUO1∆C3) lacking activation sequences. The evidence supports the important role of DAZ1 in GC shape partial morphogenesis. The C-terminus of DUO1 may regulate some target genes that affect GC body elongation. Furthermore, an intact DUO1 is shown to be indispensable for GC shape and nucleus elongation and subsequently for timely division and sperm cell morphogenesis. The development of the GC cytoplasmic projection is regulated independently of DUO1, and all its target genes were able to form it.