Chapter 4 BOT3015L Biology of Flowering Plants: Reproduction Gametophytes, Fruits, Seeds, and EmbryosTodayLife cyclesAngiosperm life cycleSlide 5Microsporogenesis in the antherFormation of microspores & male gametes.Mature microgametophytePollination to fertilization pollen tube growthSlide 10Slide 11Megasporogenesis within the ovule within the ovaryFormation of megaspores & female gametes.MegagametophyteSlide 15Slide 16FertilizationMegagametophyte after double fertilizationSlide 19Seed developmentSlide 21Slide 22Slide 23PowerPoint PresentationFruit typesSlide 26BerrySlide 28Slide 29DrupeSlide 31PomeSlide 33AggregateSlide 35Multiple fruitSlide 37??Slide 39Pawpaw for funFruits and seed dispersal dehiscenceFruits and seed dispersal waterFruits and seed dispersal windFruits and seed dispersal animals by attachmentHomework germination observationsChapter 4BOT3015LBiology of Flowering Plants: ReproductionGametophytes, Fruits, Seeds, and EmbryosPresentation created by Danielle SherdanAll photos from Raven et al. Biology of Plants except when otherwise noted• Alternation of generations (sporic meiosis)• Alternation of generations in angiosperms• Angiosperm gametophytes• microgametophyte• megagametophyte• Double fertilization** (endosperm and embryo)• Seeds• Fruits****Distinguishing characteristics of angiospermsToday• Alternation of generations (sporic meiosis)• Alternation of generations in angiosperms• Angiosperm gametophytes• microgametophyte• megagametophyte• Double fertilization** (endosperm and embryo)• Seeds• Fruits****Distinguishing characteristics of angiospermsLife cyclesFrom Outlaw’s lecture seriesAngiosperm life cycleFrom Outlaw’s lecture seriesLast weekThis weekIn the next weeksToday• Alternation of generations (sporic meiosis)• Alternation of generations in angiosperms• Angiosperm gametophytes• microgametophyte• megagametophyte• Double fertilization** (endosperm and embryo)• Seeds• Fruits****Distinguishing characteristics of angiospermsMicrosporogenesis in the antherMicrosporocyte (a.k.a. microspore mother cells) undergo meiosis to produce four dissimilar microspores.Lily anther, immature, cross sectionFormation of microspores & male gametes.Microspore mother cellEntire Male Gametophyte (angiosperms): **1 round of mitosis to yield 2 nuclei (generative + vegetative).**The generative nucleus divides again mitotically to yield 2 sperm. for sex“housekeeping”Mitosis of generative nucleusFrom Outlaw’s lecture seriesMature microgametophyteMature antherlilyMature pollen telegraph plantNote: Some pollen are shed before the generative cell divides mitotically to produce the two sperm cells, some pollen are shed after (as shown above)Sperm cellsThe protective wall and efficient dispersal of microgametophytes are two adaptations to terrestrial life (compare to flagellated gametes being released)Pollination to fertilizationpollen tube growthAngiosperm life cycleFrom Outlaw’s lecture seriesToday• Alternation of generations (sporic meiosis)• Alternation of generations in angiosperms• Angiosperm gametophytes• microgametophyte• megagametophyte• Double fertilization** (endosperm and embryo)• Seeds• Fruits****Distinguishing characteristics of angiospermsMegasporogenesis within the ovule within the ovaryThe swollen base of the carpel (megasporophyll) is the ovary. Ovules form on the inside and remain attached for nutrition. The megaspore mother cell (2n) is inside the ovule; it gives rise (through meiosis) to the megagametophyte, which completes its entire life within the ovule wall (later, seed coat). From Outlaw’s lecture seriesFormation of megaspores & female gametes.Megaspore mother cellMeiosisEntire Female Gametophyte (angiosperms): **3 round of mitosis to yield 8 nuclei .**Egg near micropylar end of female gametophyte.**Polar nuclei in the center of female gametophyte. 3 degenerateMitosisMitosisMitosisFertilization—next slidea.k.a. polar nucleiFrom Outlaw’s lecture seriesMegagametophyte(Before migration of polar nuclei to center)8-nucleate megagametophyte within ovule of lily (only 6 nuclei are visible in this section)Megagametophyte******Angiosperm life cycleFrom Outlaw’s lecture seriesToday• Alternation of generations (sporic meiosis)• Alternation of generations in angiosperms• Angiosperm gametophytes• microgametophyte• megagametophyte• Double fertilization** (endosperm and embryo)• Seeds• Fruits****Distinguishing characteristics of angiospermsFertilizationFertilizationOrdinary fertilization event: 1 male gamete (n) + 1 female gamete (n) = zygote (2n)Second fertilization event: 1 male gamete (n) + 2 female gametes (n + n) = endosperm (3n)DoubleFrom Outlaw’s lecture seriesMegagametophyte after double fertilizationToday• Alternation of generations (sporic meiosis)• Alternation of generations in angiosperms• Angiosperm gametophytes• microgametophyte• megagametophyte• Double fertilization**• Seeds• Fruits****Distinguishing characteristics of angiospermsSeed developmentmaturedicot - two cotyledonsimmatureThree tissue systems:DermalVascularCortex or GroundAll cells of the plant are part of these three systems and originate at meristems. . . A reminder that endosperm is formed in all angiosperms, but does not persist in dicots. In dicots, cotyledons are the primary source of nutrients for germination.Seed developmenttypical monocot (wheat) seed with ovary wall (pericarp) Monocots have one cotyledon that matures during germinationSource of nutrition for seed germination: endosperm(compare to dicot)Angiosperm life cycleFrom Outlaw’s lecture seriesToday• Alternation of generations (sporic meiosis)• Alternation of generations in angiosperms• Angiosperm gametophytes• microgametophyte• megagametophyte• Double fertilization** (endosperm and embryo)• Seeds• Fruits****Distinguishing characteristics of angiospermsAngiosperm seeds are in a vesselAll seeds have a seed coat(plus embryo & nutritive supply) From Outlaw’s lecture seriesThis simple fruit is derived from one carpel with several ovules and has marginal/parietal placentation.Reminder: carpels are modified leavesPisum (Leguminoseae familyFruit types•Simple - one carpel or fused carpels•Berry•Drupe•Pome•Aggregate•Multiple•Simple - one carpel or fused carpels•Berry - each carpel contains many seeds, inner layer of carpel