ABSTRACT

The tribe Camelineae (Brassicaceae) contains eight genera: Arabidopsis, Camelina, Capsella, Catolobus, Chrysochamela, Neslia, Noccidium and Pseudoarabidopsis. Little is known about pollen morphology in these taxa, and this limits research on gene flow, aerobiology, reproductive biology, systematics and palaeobotany. In this study, pollen from 13 taxa representing all of the genera in the tribe Camelineae were examined using light and scanning electron microscopy. Measurements of pollen size in Camelina (mean 26.4 µm) and Arabidopsis (mean 30.4 µm) showed that these genera contain taxa with relatively large pollen that could be classified as medium-sized pollen. The largest pollen were from Camelina microcarpa (mean 37.6 µm) and C. sativa (mean 35.6 µm). Conversely, Pseudoarabidopsis had the smallest pollen (mean 18.4 µm) in the Camelineae. Capsella bursa-pastoris was distinct in the tribe in having tectum discontinuities. Catolobus and Neslia shared a similar pollen shape that tended to be subspheroidal and less prolate than others in the tribe. Noccidium had distinct microverrucate elements on its colpus membrane. Within Camelina, variations in pollen size and stratification were observed among the five species studied. The pollen morphology of Chrysochamela deviated from that of other members of the tribe, and it was distinct in having a homobrochate reticulum and the thickest exine, sexine and infratectum. These results support research on diverse topics including pollen dispersal and gene flow in Camelina, pollen development in Arabidopsis thaliana and phylogenetic studies in the Brassicaceae.

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