Sexual and apomictic seed development in the vulnerable grass Bothriochloa biloba

Abstract

Embryological investigations on three populations of the vulnerable grass species Bothriochloa biloba point to a complex reproductive system involving both sexual and apomictic mechanisms. The apomictic mode in this species is far more complicated than has been reported earlier in the genus. It includes non-recurrent parthenogenesis and pseudogamy in the sexual embryo sac, as well as recurrent apospory and adventive embryony from somatic cells. Furthermore, multiple aposporous embryo sacs occur that are not limited to the typical Hieracium and Panicum types. Evidence from bagging individual inflorescences and pollination of dissected gynoecia indicated that sexually reproducing florets were self-compatible. Both diploid and tetraploid plants were found in three populations, and one population had triploid and hexaploid plants as well.