* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Angiosperm Reproduction
Evolutionary history of plants wikipedia , lookup
Gartons Agricultural Plant Breeders wikipedia , lookup
Ornamental bulbous plant wikipedia , lookup
Plant nutrition wikipedia , lookup
History of botany wikipedia , lookup
Plant stress measurement wikipedia , lookup
Plant use of endophytic fungi in defense wikipedia , lookup
Plant defense against herbivory wikipedia , lookup
Plant breeding wikipedia , lookup
Plant secondary metabolism wikipedia , lookup
Plant evolutionary developmental biology wikipedia , lookup
Pollination wikipedia , lookup
Plant ecology wikipedia , lookup
Plant morphology wikipedia , lookup
Plant physiology wikipedia , lookup
Sustainable landscaping wikipedia , lookup
Perovskia atriplicifolia wikipedia , lookup
Flowering plant wikipedia , lookup
Bozeman – Plant Control - 121 Angiosperm Reproduction Chapter 38 123 The Flower Plant Reproduction Sporophyte (diploid) • produces haploid spores via meiosis Gametophyte (haploid) • produce haploid gametes via mitosis Fertilization • joins two gametes to form a zygote Reproduction – Double Fertilization Reproduction – Double Fertilization • Microsporangium sperm (inside pollen grain) • Megasporangium egg (inside ovule) • After fertilization – Ovule seed coat – protection – Ovary fruit – seed dispersal Reproduction – Double Fertilization • Pollen from the anther lands on the stigma • A pollen tube containing 2 sperm cells forms and grows down the style toward the ovule • The ovule contains an embryo sac: – Micropyle end – egg and 2 synergids – Middle – 2 polar nuclei – Opposite end – 3 antipodals • The pollen tube enters the embryo sac through the micropyle – One sperm fertilizes the egg diploid zygote – 2nd sperm fuses with the 2 polar nuclei endosperm • Endosperm – provides nourishment for the developing embryo and seed 122 • IQ 38.1 • Structures AND functions • Flow Map – Double fertilization The Seed - 125 The Seed • Epicotyl – top of the embryo – Becomes the shoot tip • Plumule – first true leaves – attached to the epicotyl • Hypocotyl – below epicotyl – attached to the cotyledons • Radicle – becomes the root – Below the hypocotyl • Coleoptile – monocots only – Surrounds and protects the epicotyl Dormancy • After an egg is fertilized and the seed reaches maturity it remains dormant until the environment is favorable • Environmental cues to break dormancy – Water – Temperature – extreme cold or heat – Light – Seed coat damage - abrasion – Time Germination • Seed begins to develop • Occurs after dormancy is broken • Begins with imbibition – absorption of water • Dilutes the abscisic acid concentration • Water activates many enzymes and biochemical processes – cellular respiration ATP • The swelling of the seed cracks the seed coat so the roots and shoots can grow • Radicle roots • Hypocotyl / epicotyl shoots – Coleoptile in monocots Foliage leaves Cotyledon Epicotyl Hypocotyl Cotyledon Cotyledon Hypocotyl Hypocotyl Radicle Seed coat 124 • IQ 38.4 • IQ 38.6 b Self – Fertilization - 127 • Lowers genetic variation within a species = bad • “Selfing” • Prevention of selfing – Self – incompatibility • Carpel (female) will not accept the pollen if from the same plant – pollen tube will not form – Reject pollen that has an S-gene matching an allele in the stigma cells – Triggers a signal transduction pathway leading to a block in growth of a pollen tube • Carpel will only accept pollen after all pollen is gone from flower Self - Fertilization – Dioecious – separate male and female individual plants – Monoecious – separate male and female flowers on the same plant that mature (bloom) during different times – Structural • Short stamens with long carpels • Shrot carpels with long stamens Self - Fertilization Stigma Stigma Anther with pollen Why do flowers die? • Timing Life span of the whole flower is regulated for ecological and energetic reasons, but the death of individual tissues and cells within the flower are coordinated at many levels to ensure correct timing. Some floral cells die selectively during organ development, whereas others are retained until the whole organ dies. • Flowers are metabolically expensive • Flowers that are no longer producing pollen would interfere with pollination of other flowers. 126 • Bubble map – preventing self fertilization • Summary 129 – Bozeman Plant Defense Plant Hormones and Responses to Stimuli Chapter 39 131 REVIEW • Communication in Organisms – Cell to cell Recognition • Glycoproteins and glycolipids – Carbohydrates – Cell Junctions • Gap Junctions • Plasmodesmata CELL WALL 1 Reception CYTOPLASM 2 Transduction – Short Distance • Local Regulation – Growth factors – Paracrine Signaling – Synaptic Signaling – Long Distance • Hormones Relay molecules Receptor Hormone or environmental stimulus Plasma membrane 3 Response Activation of cellular responses Etiolation (growth in darkness) • The stems of plants raised in the dark elongate much more rapidly than normal, a phenomenon called etiolation. De-etiolation (greening up) pathway • 1. Light signal detected by phytochrome receptor • 2. cGMP stimulates a kinase which stimulates transcription factor 1 OR Ca2+ stimulates transcription factor 2 3. Translation produces enzymes that cause the plant to green up! Plant Hormones • Travel in the sap of plants (xylem and phloem) • Types – Auxins – Indoloacetic Acid (IAA) • Cell Growth cell elongation – Cytokinins • Cell Division cytokinesis – Gibberellins • Cell Growth cell division and cell elongation – Brassinosteroids • Cell growth cell elongation and cell differentiation – Abscisic Acid • Slows cell growth high concentrations inhibit germination • Water washes out acid to break dormancy – Ethylene Gas • Fruit Ripening 130 • IQ 39.2 • Summarize each of the hormones and their functions Plant Hormones - 133 • The balance of hormones triggers a response • Synergistic – hormones work together – Ex: Auxins and Gibberellins • Antagonistic – hormones counteract each other – Ex: Auxin and Abscisic Acid Plant responses - Phototropism • Plants response to light • Auxin • Auxin is produced in the apical meristem of the shoot and travels down by active transport to the zone of elongation. • If equally produced then the stem will grow straight • Auxin will concentrate on a shady side of a stem • Therefore the plant stem will bend toward the light because there is greater elongation on the shady side. Darwin and Darwin Phototropism (1880) tip responds to light Light Tip removed Tip Base covered Tip covered by opaque covered by opaque shield by transcap parent cap • • • • • Plant responses - Gravitropism Plants response to gravity – geotropism Auxins Shoots show negative gravitropism (against gravity) Roots show positive gravitropism (with gravity) Statoliths – starch containing plastids in the root cap help trigger root gravitropism Plant Responses - Thigmotropism • Plants response to touch • Not well understood • Vines will climb up walls or trees for support based on touch • Some plants respond to touch rapidly – Action potentials similar to nervous system Abscission • Leaf and Fruit falling off the plant • Auxin and Ethylene • Ethylene ripens the fruit • NO ABSCISSION – 0.5 mm – Leaf IAA > Stem IAA – Fruit IAA > Stem IAA • ABSCISSION – – Leaf IAA < Stem IAA – Fruit IAA < Stem IAA Protective layer Abscission layer Stem Petiole Parthenocarpy • Production of seedless fruit – Fruit is produced without fertilization in the ovule • Gibberellins, Auxins, and Cytokinins • Mutation in nature – Plants can’t sexually reproduce • Useful for agriculture 132 • Free choice • Tropisms – Plant responses Photoperiodism - 135 • Response of plants to changes in the photoperiod (relative lengths of day and night) • Plants detect the color, wavelength, direction, and intensity of light • Plants maintain a circadian rhythm – internal biological clock – Phytochromes – absorb red wavelengths of light – Pfr – far red – wavelengths 730 nm - light – Pr - red – wavelengths 660 nm - dark Photoperiodism • • • • Pr – synthesized in plant leaves Pr and Pfr are in equilibrium during daylight Pr – accumulates at night Pr Pfr at daybreak until equilibrium is reached – Seeds will not germinate until Pr begins converting to Pfr • Length of the night determines the circadian rhythm Flowering Plant Groups • Long-day – flower in the spring and early summer when daylight is increasing • Short-day – flower in the late summer and early fall when daylight is decreasing • Day-neutral – do not flower in response to light – Respond to some other environmental cue • H2O or temperature • Floragin hormone triggers flowering of plant based on light cue 134 • IQ 39.6 Plant Defense - 137 • Herbivory – animals eating plants – Physical defense • Thorns and toxic chemicals – Many of the toxic chemicals are turned into medicines • Recruit predators to attack the animals – Wasps lay their eggs in caterpillars which then hatch and eat the caterpillars from the inside out Plant Defense • Pathogens – – Physical barrier – skin – epidermis – Pathogen recognition – gene for gene recognition • Avr allele in pathogen creates a ligand that is recognized by a receptor in the plant cell coded for by the R allele – Oligosaccharins – elicits the production of antimicrobial compounds to attack pathogens – Hypersensitive Response – Infected release a signal to warn the rest of the plant and then the cells undergo apoptosis and kill themselves to prevent the spread of the disease (Systemic acquired defense) • Salicylic acid – signal sent (used in asprin) 136 • Structure your knowledge #3 • Summarize how plants defend themselves against pathogens 138-139 • EK’s 38 and 39 140-141 • Big Idea Summary