Adapting Quantum Dot staining in a nectarless plant, Solanum sisymbriifolium, to measure self- and cross-pollen deposition rates.

Paternity analyses of seeds only reflect the final result of pollination, a highly stochastic processwith many different fates, the successful siring of a seed only being one of them. Recentadvances in the use of UV-fluorescent nanocrystals, such as Quantum Dots, allow individualpollen grains to be color-tagged, enabling us to track their movement and determine their fate .However, flowers with poricidal anthers, which are commonly nectar-less and buzz-pollinated,can be challenging to tag due to their narrow anther openings. With this Degree Project, I aimedto i) develop a method for injecting Quantum Dot solution into anthers of buzz-pollinatedSolanum sisymbriifolium and efficiently tag pollen grains, ii) use the proposed method todetermine self-pollen deposition rates along a visitation sequence and iii) estimate pollentransfer rates in consecutive visits by Bombus terrestris. The technique achieved high stainingefficiency within the anther (95.2 ± 11.9%). I found that the proportion of tagged pollen tountagged pollen grains deposited on the stigma of the first flower visited was significantly lowerthan the proportion of tagged pollen inside the anther, suggesting unexpected destaining or lossof tagged pollen during transport which resulted in reduced transfer efficiency of pollen withQDs tags. Using tagged pollen only, I estimated that the rate of self-pollination in the secondand third visited flower is around 50%, 95% CI [37.9%, 63.0%]). I found that pollen depositionincreased with more intense buzzing behavior, while greater herkogamy (spatial separation ofsexual organs) selectively increased cross-pollen deposition. These results suggest thatQuantum Dots can be applied to species with poricidal anthers, though the pattern of pollendestaining observed here should be thoroughly investigated. Further research should focus ondetermining the viability of the staining and the adhesion mechanism in pollen grains, becausethe ability to tag and track individual pollen grains would allow us to study pollen transfer inbuzz pollinated species within natural settings.