Abstract Detail


Ramadoss, Niveditha [1], Orduño-Baez, Amy Karina [2], Portillo, Carlos [3], Steele, Scarlet [3], Rebman, Jon [4], Flores-Renteria, Lluvia [5].

Understanding the factors influencing reduced seed production of a spiny and struggling cactus.

Cylindropuntia wolfii is a rare and endemic cactus that occupies the extremely hot desert of the US - the Sonoran. However, it is predominant in the Mountain Springs area (Imperial County, CA) at the border of California and Baja California. It is an ecologically important species as it offers protection to wild animals and birds, microhabitat for insects, and food reserve for bees. Previously, our lab characterized the sexual system of C. wolfii as functionally dioecious (individuals are either functionally male or female). Tentative field observations showed that although C. wolfii produces a lot of flowers, the females rarely produce fruits with mature seeds. Thus our aim is to identify factors influencing reduced seed production in this species. Several extrinsic and intrinsic factors can affect seed production. Extrinsic factors such as lack of pollinators can result in unfertilized ovules and lack of mature seeds. In order to evaluate whether extrinsic factors influenced the seed production we conducted a field survey for visitors and measured the pollinator visitation rate between male and female plants. Our results showed that males attracted more pollinators than females. This biased visitation could affect the seed production especially when the pollinator density is low, as the females would be rarely visited. On the other hand, intrinsic factors can be developmental (pollen viability and stigma receptivity) or genetic (deleterious mutations accumulated due to inbreeding). In order to evaluate whether intrinsic developmental factors affected seed production we performed an in-vivo pollen germination test. Our results showed that the pollen from male flowers (since females do not produce pollen) were viable and the pollen tube germination was observed in both male and female stigma and style. This suggests that pollen viability and stigma receptivity are not related to the reduced seed production in C. wolfii. Experiments are underway to test the effect of genetic factors on the reduced seed set. This research will enhance our understanding of the limited knowledge of cactus reproductive biology, especially in the genus Cylindropuntia, which forms a major group of desert plants in the United States.

1 - 6621 MONTEZUMA ROAD APT 207, 6621 MONTEZUMA ROAD APT 207, SAN DIEGO, CA, 92115, United States
2 - University of California Santa Cruz
3 - San Diego state university
4 - San Diego Natural History Museum
5 - San Diego State University, 4319 Yale Ave, San Diego State University, La Mesa, CA, 91942, United States

seed set
sexual dimorphism .

Presentation Type: Oral Paper
Number: EC02005
Abstract ID:343
Candidate for Awards:None

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