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1 Section for Crop Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet 2 Department of Plant and Environmental Sciences, University of Copenhagen 3 Section for Crop Sciences, Department of Plant and Environmental Sciences, Faculty of Science, Københavns Universitet
Several members of the Kalanchoë genus are popular as ornamental plants. Cross-breeding and wide hybridisation are essential to continuously introduce novel traits into cultivated plant material. This study aimed to identify the major factors related to the stigma affecting cross-pollination in the Kalanchoë blossfeldiana. Pollen tube growth after pollination of K. blossfeldiana 'Jackie' and 'Reese' was examined at different stigma developmental stages. Five distinct developmental stages were identified based on changes in morphology and activity of stigmatic peroxidase. After reciprocal pollination at the five stigma developmental stages, fluorescence microscopy was used to estimate the number of pollen tubes in situ. Both cultivars had receptive stigmas from stage I to IV, which concurred with the continuous expansion of the stigma covered with exudates. No pollen tube growth was observed at stage V for both cultivars. The number of pollen tubes was significantly higher in carpels pollinated at stage III, characterized by loose arrangement of the papillae and maximal amount of exudates, compared to all other developmental stages. Stigmas showing drying exudates and absence of peroxidase exhibited a relatively decreased number of pollen tubes in situ. No pollen tubes germinated on wilting stigmas. The arrangement of the papillae, the presence of exudates and peroxidase activity affected the number of pollen tubes in cross-pollination of K. blossfeldiana cultivars 'Jackie' and 'Reese'. These results will help breeders to better select the optimal time for effective pollination. The findings may be applicable for other cultivars of K. blossfeldiana and relevant for different species of Kalanchoë. © 2014 Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.
Acta Physiologiae Plantarum, 2014, Vol 36, Issue 7, p. 1763-1769
Cross-breeding; Exudates; Papillae; Peroxidase; Pollen tubes; Stigma morphology
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