Angiosperm Reproduction Chapter 19

Major Evolutionary Advances Life - 3,800 mya Prokaryotic cell/autotrophic Place on the time scale, the following events: 1. Earth 2. Prokaryotes 3. Eukaryotes 4. Multicellular life 5. Vascular tissue 6. Seeds 7. Flowers Eukaryotic cell - 1,400 mya Multicellar plants - 1,000 mya Vascular tissue - 430 mya Needed on land - why? Seeds - 350 mya Flowers - 140 mya Earth Forms Prokaryotic Cells Eukaryotic Cells Multicellular Plants Vascular tissue Flowers 5,000 mya 4,000 3,000 2,000 1,000 Seeds

Flower variation Complete Incomplete has all 4 whorls lacks one or more of whorls (sepals, petals, stamens or carpels)

Flower variation Perfect Imperfect both androecium and gynoecium carpellate or staminate flower only if both carpellate and staminate flowers are on same plant called monoecious if on different plants called dioecious

Fertilization Pollination: transfer of pollen grains from anther to pistil Pollen grain onto stigma Germination - tube cell produces pollen tube, generative cell divides to form 2 sperm cells Double Fertilization: 2 sperm enter embryo sac: 1 sperm fertilizes egg to form zygote other sperm fertilizes polar nuclei to form endosperm

Sexual Reproduction Four events must occur for successful reproduction in angiosperms: Pollination Pollen grain growth to ovule Successful fertilization Successful seed development

Sexual Reproduction Inbreeding Outcrossing Result of self-pollination & self-fertilization Results in inbreeding depression Outcrossing Result of cross-pollination & cross-fertilization Results in hybrid vigor What process is “best”? Why? How do plants promote this?

Sexual Reproduction Unisexual flowers Monoecious plants Dioecious plants

Sexual Reproduction Bisexual flowers Hibiscus Bisexual flowers Protandry - stamens mature before stigma Protogyny - stigma matures before stamens Heterostyly - physical separation between stigma and stamen Epilobium (fireweed) Protandry Magnolia

Sexual Reproduction Bisexual flowers Self-incompatibility Pollen grain-stigma surface: no germination Pollen tube growth: tube “dies” Fertilization: inviable zygotes Amarylis

Pollination Define: transfer of pollen to stigma How is self-fertilization prevented (or reduced) through pollination mechanisms? unisexual flowers (monoecious plants) unisexual flowers (dioecious plants) protandry protogyny heterostyly

Fertilization: Define: combining of sperm + egg AND sperm + polar nuclei = double fertilization ovule

Fertilization megagametophyte microgametophyte (female gametophyte) ovule

Fertilization

Fertilization What occurs after double fertilization? embryo development next generation endosperm development nourishment for embryo What structure is formed? seed embryo endosperm seed coat Where is the seed housed? inside ovary matures into a fruit ovary wall = pericarp

Seed germination & growth

How might reproductive success be measured in an angiosperm?

Gyno-dioecious species Hermaphroditc flowers on some plants Funk, Lisa. 1997. A comparison of reproduction in self and outcrossed purple poppy mallow flowers (Callirhoe involucrata). Results presented at the 1997 Nebraska Academy of Sciences Annual Meeting. Gyno-dioecious species Hermaphroditc flowers on some plants Male-sterile flowers on other plants

4 Treatments Fruit set measured Selfed Outcrossed Pollinator excluded Funk, Lisa. 1997. A comparison of reproduction in self and outcrossed purple poppy mallow flowers (Callirhoe involucrata). Results presented at the 1997 Nebraska Academy of Sciences Annual Meeting. 4 Treatments Selfed Outcrossed Pollinator excluded Control Fruit set measured

What conclusions can be drawn?

What conclusions can be drawn? Funk, Lisa. 1997. A comparison of reproduction in self and outcrossed purple poppy mallow flowers (Callirhoe involucrata). Results presented at the 1997 Nebraska Academy of Sciences Annual Meeting. What conclusions can be drawn? What is the role of gyno-dioecy in plant reproduction and reproductive success in Callirhoe involucrata?