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
REPRODUCTION
ASEXUAL 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 SELFPOLLENATE
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.