Polarized Cell Expansion and Heterochronic Shift in Angiosperm Spermatogenesis

Single cell expansion of the growing pollen tube and the coordinated control of germ cell division and sperm cell fate specification, are landmark features of the developing male gametophyte. We applied the Agilent 44K tobacco gene chip to conduct the first transcriptomic analysis of the tobacco male gametophyte. We have performed a comparative study with the Arabidopsis root-hair trichoblast transcriptome to evaluate genetic factors and common pathways in polarized cell-tip expansion. Extension of our analysis beyond the second haploid mitosis allowed construction of a genetic model likely to have instigate the heterochronic shift in Angiosperm spermatogenesis.