2017 ASHS Annual Conference

Self-Incompatibility systems were evaluated in Abelia chinensis, Abelia engleriana and Abelia xgrandiflora. Self and cross pollinations were performed in greenhouse-grown plants on recently opened flowers. Pollinations were evaluated at one or two days after pollination. Pollinated flowers dropped after the second day after pollination. Styles were removed one and two days after pollination, fixed in a solution of ethanol and glacial acetic acid (3:1) for at least 24 hours, transferred to a solution of NaOH 4N for 12 to 24 hrs. to soften the tissues, and then stained with 0.1% decolorized aniline blue with 0.1 M K₃PO₄. Stained styles were analyzed for pollen tube growth under an inverted epifluorescent microscope. Pollen tubes were inhibited in the upper half of the style on self-pollinations and reached the base of the style on cross-pollinations. Inhibition in the style suggests the presence of gametophytic self-incompatibility in Abelia. In vitro pollen germination was evaluated in A. chinensis, A. engleriana and A. serrata. The most effective germination medium consisted of 10% sucrose, 0.01% H₃BO₃, 0.02% CaCl₃ and 0.5% agar with a pH of 7. Pollen did not germinate in liquid medium and sucrose concentrations of 15, 20 or 25% were not effective. Three samples of pollen from different dehiscent anthers of recently opened flowers from greenhouse-grown plants were placed on top of a slide containing germination medium. Slides were placed on a petri dish with a wet paper towel to ensure 100% humidity and cultured in light at 28.5 ± 0.5°C. Germination of 100 pollen grains was evaluated at 2hrs and 24hrs after culture. Overall, Abelia engleriana had the highest germination, with 86% of the grains germinating after 24 hrs of culture. A. serrata had 38% germination, while A. chinensis exhibited very low germination in the three different pH levels tested: approximately 13%, 8% and 3% in medium pH 6, 7, and 8 respectively. Pollen nuclei identification was evaluated in in vitro germinated pollen grains stained for one hour with 0.25 mg∙L^-1 or 0.5mg∙L^-1 of a 4’, 6-diamidino-2-phenylindole (DAPI) solution prepared with glass distilled water, and evaluated under a fluorescent microscope. Observations indicate the presence of three nuclei in Abelia pollen.