Abstract Detail

Pollination Biology

Callen, Steven [1], Zweck, Justin [1], Zander, Tracy [1], Miller, Allison [1], Bernhardt, Peter [1].

Sexual reproduction and self-compatibility of the invasive vine kudzu (Pueraria montana) in Missouri roadside populations.

While kudzu (Pueraria montana var. lobata), an invasive vine native to Asia, dominates landscapes through clonal growth, its sexual reproduction in North America is poorly understood. To assess the potential influence of sexual reproduction in facilitating invasion, we first compared pod/seed production in flowers exposed to pollinating insects (open) versus unexposed flowers (bagged). Open flowers were primarily visited early in the flowering season (June-July) by Megachile sculpturalis (giant resin bee) and later in the season (August-September) by Apis mellifera (honeybee), both of which are non-native bees of Asian/Eurasian origin. Foraging patterns showed individual bees visiting multiple flowers on the same inflorescence. Pollen load analysis confirmed these insects as effective pollinators. No pods developed in bagged inflorescences. Florescence microscopy revealed that pods do not develop without pollinators because self-fertilization is impeded by a stigmatic cuticle. We next performed hand-pollination experiments to determine whether pod/seed set varied by treatment. Geitonogamous (flowers on the same vine) and within-patch treatments set significantly less fruit/seed than cross-pollinations. Florescence microscopy showed pollen tubes from both geitonogamous and cross-pollinations reaching the ovules within 24 hours post-pollination. Because pollen tubes reached the ovules in all treatments, but pod/seed set was significantly reduced in geitonogamous pollinations, we suspect a late-acting, partially self-compatible breeding system. The self-compatibility index for fruit set (SCI = 0.36) and for seed set (SCI = 0.13) indicate a low ability for self-fertilization. To assess whether fruit/seed set under natural conditions was similar to any treatment, we compared open-pollinations within two populations to hand-pollinations. In one population, pod/seed set in natural conditions were more similar to geitonogamous and within-patch treatments than to cross-pollination treatments. Alternatively, in a second population, pod/seed set in natural conditions were equivalent to cross-pollination treatments. The differences in pod/seed set between these two populations may result from differences in the genetic composition of these populations, i.e. from the number of genets (genetically-distinct individuals) and ramets (clones). To investigate the influence of genetic composition on mating opportunities, future studies will assess the spatial genetic structure and clonal architecture within kudzu populations. These Missouri kudzu populations appear to be partially self-compatible, requiring some degree of cross-pollination to set pod/seed. To investigate possible changes associated with invasion, future studies will compare pollination and mating systems in Missouri to China populations.

Broader Impacts:

1 - Saint Louis University, Biology, 3507 Laclede Ave., St. Louis, Missouri, 63103, United States

Keywords:
pollination
kudzu
Pueraria montana
invasive species
plant mating systems
invasive mutualism.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Grand Salon A - D/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 5:30 PM
Number: PPL010
Abstract ID:620
Candidate for Awards:None