| Tóm tắt: | <p>Abstract</p> <p>Background</p> <p>Although <it>Nicotiana attenuata </it>is entirely self-compatible, chemical and other floral traits suggest selection for the maintenance of advertisement for moth pollinators.</p> <p>Results</p> <p>Experimental exclusions of pollinators from plants with emasculated flowers in natural populations in southern Utah during an outbreak of the hawkmoth <it>Hyles lineata </it>revealed that 24% of the seed set could be attributed to insect pollination, and eliminated wind pollination and apomixis as contributing to seed set. Hence these moths can mediate gene flow when self-pollen is unavailable. To quantify gene flow when self-pollen is available, plants were transformed with two marker genes: hygromycin-B resistance and β-glucuronidase. The utility of these genetic markers to measure gene flow between plants was examined by mixing pollen from plants homozygous for both genes with self-pollen in different ratios and hand-pollinating emasculated flowers of plants growing in a natural population. The proportion of transformed seeds was positively correlated with the amount of transformed pollen applied to stigmas. In glasshouse experiments with the hawkmoth <it>Manduca sexta </it>and experimental arrays of transformed and wild-type plants, pollination mediated by moths accounted for 2.5% of the seed set.</p> <p>Conclusions</p> <p>Even though moth pollination is rare and highly variable for this largely selfing plant, <it>N. attenuata </it>opportunistically employs a mixed-mating system.</p>
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