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.