Abstract Galinsoga quadriradiata Ruiz & Pav. is an annual weedy plant that can be found all over the world. It belongs to the Asteraceae family and is recognised as one of the invasive foreign plants in Poland, which are native to Central and South America. The aim of this study was to describe the reproductive features of Galinsoga quadriradiata focusing on the changes that occur during microsporogenesis and microgametogenesis along with the morphology of its pollen. As it is typical of the eudicot clade of Angiosperms, cytokinesis of G. quadriradiata is simultaneous. The pollen grains are tricolporate with spiny outer walls and the course of the microsporogenetic process is fairly typical of the Echinatae group of weed plants. The high viability of the pollen grains, which mature unequally in the inflorescences, and the proper course of meiosis determine whether a plant has the invasive character of Galinsoga quadriradiata.

The Arabidopsis CDKG;2 gene encodes a putative cyclin-dependent Ser/Thr protein kinase of unknown biological function. This gene shows structural similarity to animal and human cyclin-dependent (PITSLRE) kinases. This study used the homozygous knockout cdkg;2 mutant based on T-DNA insertional line SALK_090262 to study the effect of mutation of the CDKG;2 gene on explant response and in vitro plant regeneration. For callus induction and proliferation, hypocotyls and cotyledons of 3-day-old seedlings of cdkg;2 and A. thaliana ecotype Col-0 were cultured on solid MS medium supplemented with 2,4-D (2 mg l-1). Organogenesis was induced after callus transfer on MS + TDZ (0.5 mg l-1). The initiation time of callus and shoot induction differed between the mutant and control cultures. Shoot regeneration after callus transfer on MS + TDZ was delayed in cdkg;2 (31 days versus 7 days in Col- 0). Shoots formed on callus derived from Col-0 hypocotyls but not on cotyledon-derived callus; in cdkg;2, shoots developed on both callus types. Mutant shoots did not form roots, regenerants were dwarfed, and inflorescences had small bud-like flowers with a reduced corolla and generative organs. Abnormalities observed during cdkg;2 organogenesis suggest a role of CDKG;2 as a regulator of adventitious root initiation