Ch 30 & 42 - Plant Reproduction Flashcards
Complete Flower
Has all 4 whorls
Perfect
Has both male and female parts
Reproduction differences between angiosperms or animals
Both male and female in same structure
Reproductive organs are not permanent parts of individual
Pollen
Anther contain 4 microsporangia
Microsporangia produce microspore mothers (2n)
Mothers produce 4 hapolid (1n) microspores via meiosis
Microspore undergoes mitosis and becomes pollen
Pollen cell divides to form 2 sperm cells
Mature pollen is binucleate
Embryo Sac Formation
Ovule contains diploid megapore mother cell
Mother undergoes meiosis to make 4 haploid megaspore
Only one survives
Produces 8 haploid nuclei arrarnged in groups of 2
Enclosed in 7 celled embryo sac
Angiosperm Life Cycle
Embryo Sac: 8 haploid nuclei Nucleus migrate towards center: polar nuclei Cell walls form around other 3 nuclei One cell becomes egg Other cells become synergids 3 cells at other end become antipodals
Pollination
mechanical transfer of pollen from anther to stigma
Develop pollen tube to reach embryo sac
Pollen tube reaches ovule, enters one of the synergids, releases two sperm cells
Double fertilization
One sperm unites with egg to form diploid (2n) zygote
Sperm unites with the two polar nuclei to form triploid (3n) endosperm - provides nutrients
Meristem
leading growing structure
Phase Change
When plants change from juvenile to adult, and can begin flowering
Usually leaves change, etc
Flowering Genes
EMF: prevents early flowering, found in Arabidopsis
LFY: overexpression of flowering gene, reduces juvenile length
Flower Production Pathways
Light dependent
Temperature dependent
Gibberellin dependent
Autonomous
Light Dependent Pathway
Also called Photoperiodid
Sensitive to amount of light received throughout day
Obligate: Sharp distinction in day length
Facultative: Day length doesn’t totally determine flowering
Phytochromes & Cryptochromes
Chemicals of Light dependent pathways
CO turns on genes that express LFY
Phyto: regulates CO transcription
Cyroto: modulates Co protein, protects from degradation during day
Temperature Dependent Pathway
Vernalization: period of chilling before flowering
Gibberellin Dependent Pathway
Gibberellin binds to LFY promoters
Promotes flowering
Delays flowering if not enough present
Autonomous Pathway
Doesn’t depend on external clues
Day-neutral plants can count and remember node location
Florally determined: Flower at specific node
Related to root development
Pollination
Pollen placed on stigma
Self: pollen of anther pollinates stigma of same flower
Cross or Outcrossing: pollen of anther of one pollinates stigma of another flower
Pollinators
Bees are most common pollinators Flowers guide pollinators with UV designs Flowers that attract: butterflies: landing platforms moths: white or pale and are heavily scented birds: red monkeys: orange and yellow wind: small, green, odorless
Self Pollinators
Small inconspicuous flower
Flower meant to catch pollen into stigma
Favored in stable environments
Offspring more uniform
Outcrossing Promotion
Separate male and female by space
Separate by time - called dichogamous
Self incompatibility, blocked at S locus
Asexual Reproduction
Mitosis Genetically identical Common in harsh environments Used in agriculture Apoximis: cloning of diploid embryo in ovule Done by citrus, dandelion
Asexual Reproduction Clone
Cloned from parts of adult Above ground: runners or stolons Below ground: rhizomes Sprouts: suckers (apples, cherries) Adventitious plantlets: develop on surface
Protoplast
plant cell enclosed by plasma membrane
Cell division forms callus - aka group of stem cells
Tissue engineering for plants
