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CHAPTER 38: ANGIOSPERM REPRODUCTION & BIOTECHNOLOGY
BY: TREVOR GULLEDGE, ASHLEY LETO, AND JILL RICHARDS
38.1: FLOWERS, DOUBLE FERTILIZATION, AND FRUITS ARE UNIQUE FEATURES OF THE
ANGIOSPERM LIFE CYCLE
LIFE CYCLE OF PLANTS• ALTERNATES BETWEEN SPOROPHYTE AND GAMETOPHYTES
GENERATIONS
• SPOROPHYTE PRODUCE SPORES BY MEIOSIS
• DOMINATE GENERATION
• GAMETOPHYTES PRODUCE GAMETES FROM THE SPORES BY MITOSIS
• FERTILIZAITON IS FUSION OF GAMETES MAKING A DIPLOID ZYGOTES
• THE ZYGOTES DIVIDE AND FORM SPOROPHYTES
FLOWER STRUCTURE• STAMEN
• FILAMENT HOLDS THE ANTHER
• ANTHER PRODUCE POLLEN
• CARPEL
• OVARY CONTAINS OVULES
• STIGMA CATCHES POLLEN
• STYLE HOLDS STIGMA
• PISTIL ARE A GROUP OF CARPELS
Flower Structure
MALE GAMETOPHYTES• POLLEN
• GENERATIVE CELL AND TUBE CELL
• FORM FROM MICROSPORES
• FORM FROM MICROSPOROCYTE
• COME FROM MICROSPORANGIA LOCATED IN THE ANTHER
FEMALE GAMETOPHYTES• EMBRYO SAC
• FORM FROM MEGASPORES
• FORM FROM MEGASPOROCYTE
• COME FROM THE MEGASPORANGIUM
POLLINATION• POLLINATION IS WHEN POLLEN HANGS ON A STIGMA OF A CARPEL
• TYPES
• WIND (ABIOTIC)
• BEES
• MOTHS AND BUTTERFLIES
• BIRDS
• FLIES
• BATS
DOUBLE FERTILIZATION• WHEN TWO SPERM ARE DISCHARGED INTO THE FEMALE
GAMETOPHYTE
• ONE FERTILIZES
• ONE COMBINES WITH A POLAR NUCLEI FORMING A FOOD-STORING ENDOSPERM
SEEDS• THE SEED HOLDS THE EMBRYO AND EITHER AN
ENDOSPERM OR COTYLEDONS
• SEED DORMANCY ALLOWS THE SEED TO GERMINATE IN THE RIGHT CONDITIONS FOR SURVIVING
FRUIT• PROTECTS THE SEED
• AIDS IN WIND DISPERSAL
• ATTRACTS SEED-DISPERSING ANIMALS
38.2: REPRODUCTION OF FLOWERING PLANTS
MECHANISMS OF ASEXUAL REPRODUCTION
FRAGMENTATION: SEPARATION OF PARENT PLANT INTO INTO PARTS THAT DEVELOP INTO WHOLE PLANTS
ASEXUAL REPRODUCTION PRODUCES CLONES OF THE PARENT
APOMIXIS: ASEXUAL REPRODUCTION OF SEEDS IN WHICH A DIPLOID CELL IN THE OVULE CREATES AN EMBRYO, WHICH THEN MATURES INTO SEEDS
DANDELIONS REPRODUCE ASEXUALLY
ADVANTAGES/DISADVANTAGES OF ASEXUAL VERSUS SEXUAL
REPRODUCTIONASEXUAL REPRODUCTION
ADVANTAGES: NO NEED FOR POLLINATOR, PASS ON ALL GENETIC INFO, CLONES GENETICALLY WELL ADAPTED TO ENVIRONMENT, INCREASED DISPERSION
DISADVANTAGES: MECHANISMS HAVE EVOLVED THAT MAKE IT DIFFICULT OR IMPOSSIBLE FOR A FLOWER TO SELF-FERTILIZE, IDENTICAL GENES INCREASE CHANCE OF EXTINCTION
SEXUAL REPRODUCTION
ADVANTAGES: GENERATES VARIATION, RESISTANCE TO EXTINCTION AND PATHOGENS
DISADVANTAGES: NEED FOR POLLINATOR
MECHANISMS THAT PREVENT SELF-FERTILIZATION
PREVENTION INCREASES GENETIC VARIETY BY ENSURING THAT THE SPERM AND EGG CELLS COME FROM DIFFERENT PARENTS
DIOECIOUS SPECIES: NO SELF-FERTILIZATION BECAUSE THE PLANTS EITHER HAVE CARPELS (CARPELLATES) OR STAMEN (STAMENATES)
OTHER PLANTS HAVE BOTH STAMEN AND CARPELS, BUT THEY MATURE AT DIFFERENT RATES OR ARE IN AN ARRANGEMENT THAT MAKES IT DIFFICULT FOR A POLLINATOR TO POLLINATE
SELF-INCOMPATIBILITY: A PLANT CAN REJECT ITS OWN POLLEN
S-GENES DICTATE WHETHER POLLEN IS REJECTED OR ACCEPTED (POLLEN BLOCKING)
PIN AND THRUM FLOWERS HAVE DIFFERENT LENGTH STAMENS AND STYLES WHICH FAVOR CERTAIN KINDS OF POLLINATORS
(GENETIC VARIATION) AND MAKE IT DIFFICULT TO SELF-POLLENATE
VEGETATIVE PROPAGATION AND AGRICULTURE
CUTTINGS: PLANT FRAGMENTS THAT GROW AND DEVELOP INTO A NEW PLANT
GRAFTING: WHEN A TWIG OR BUD OF ONE PLANT IS COMBINED WITH A CLOSELY RELATED SPECIES TO CREATE A SINGLE PLANT
THE PLANT THAT PROVIDES THE ROOT SYSTEM=THE STOCK
THE TWIG GRAFTED TO THE STOCK=THE SCION
ALLOWS FOR COMBINATION OF BEST GENETIC QUALITIES
TEST TUBE CLONING: FORM OF IN VITRO PLANT BREEDING USED IN THE PRODUCTION OF GM PLANTS (TRANSGENIC) AND THE INVENTION OF NEW PLANT VARIETIES (PROTOPLAST FUSION)
FROM LEFT TO RIGHT: PROTOPLASM CULTURE, AFRICAN VIOLETS, AND WINE GRAPES
38.3: HUMANS MODIFY CROPS BY BREEDING AND
GENETIC ENGINEERING
PLANT BREEDING
IN NATURE, PLANTS HYBRIDIZE ON THEIR OWN.
HYBRIDIZATION HAS BEEN USED BY ANCIENT FARMERS AS WELL AS MODERN ONES
ONCE PLANTS HAVE SUCCESSFULLY BRED, THE ONES WITH THE BEST TRAITS ARE CHOSEN
MAIZE
PLANT BIOTECHNOLOGY AND GENETIC ENGINEERING
GENES FROM UNRELATED ORGANISMS ARE INTRODUCED INTO PLANTS
GENETICALLY MODIFIED PLANTS CAN INCREASE THE AMOUNT AND THE QUALITY OF FOOD
CAN BE USED AS ECOLOGICALLY SOUND FUEL.
DEBATE OVER PLANT BIOTECHNOLOGY
THERE ARE SOME UNKNOWN RISKS OF GMO’S
HOWEVER, THE POTENTIAL FOR BENEFICIAL RESULTS MUST BE TAKEN INTO CONSIDERATION.
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