Plant Developmental Responses
Phototropism positive
Gravitropism positive negative
Thigmotropism
Old Fig Sun rising over horizon MorningNoonAfternoon Heliotropism
Old Fig c (c) Cross-sectional views Parenchyma cells retaining turgor Decrease of turgor in parenchyma cells Vascular tissue Pulvinus Leaflet Open Closed Nastic movements Mimosa
Venus fly trap (vulnerable)
(induction) Fig 6-2 Cell communication Signal transduction pathway eg: hormones
Auxin structure
The Darwins’ work on phototropism coleoptile of grass seedling ++--
Frits Went’s experiment
What’s happening?
effects a. promotes cell growth b. shoot phototropism c. root gravitropism d. apical dominance e. differentiation of vascular tissue f. prevents leaf abscision
effects a. promotes cell growth b. shoot phototropism c. root gravitropism d. apical dominance e. differentiation of vascular tissue f. prevents leaf abscision
Apical dominance (released)
effects a. promotes cell growth b. shoot phototropism c. root gravitropism d. apical dominance e. differentiation of vascular tissue f. prevents leaf abscision
used in agriculture/horticulture to: 1) promote (adventitious) rooting of cuttings 2) cause uniform flowering & fruit set 3) to give seedless fruit 4) synthetic auxins used as herbicides 5) promote growth & differentiation in tissue culture
Rooting cuttings
used in agriculture/horticulture to: 1) promote (adventitious) rooting of cuttings 2) cause uniform flowering & fruit set 3) to give seedless fruit 4) synthetic auxins used as herbicides 5) promote growth & differentiation in tissue culture
Plant tissue culture
Gibberellin structure Margaret Radley Bernard Phinney Eiichi Kurosawa
effects a. promotes stem growth b. induce flowering c. break dormancy in buds & seeds d. lower temperature threshold of growth e. increase yields f. increase size of fruit & distance between g. enhance starch digestion
Phinney’s dwarf corn
effects a. promotes stem growth b. induce flowering c. break dormancy in buds & seeds d. lower temperature threshold of growth e. increase yields f. increase size of fruit & distance between g. enhance starch digestion
(b) Do not post photos on Internet
effects a. promotes stem growth b. induce flowering c. break dormancy in buds & seeds d. lower temperature threshold of growth e. increase yields f. increase size of fruit & distance between g. enhance starch digestion
Fruit set (without seeds), size and spacing
effects a. promotes stem growth b. induce flowering c. break dormancy in buds & seeds d. lower temperature threshold of growth e. increase yields f. increase size of fruit & distance between g. enhance starch digestion
Seed germination (part of “malting” for making beer)
Cytokinin structure Carlos Miller Folke Skoog Related to adenine
effects a. promotes cell division b. cell enlargement c. tissue differentiation d. works with auxin in apical dominance e. chloroplast development f. stimulation of cotyledon growth g. delay of senescence h. used in plant tissue culture
Delay senescence
effects a. promotes cell division b. cell enlargement c. tissue differentiation d. works with auxin in apical dominance e. chloroplast development f. stimulation of cotyledon growth g. delay of senescence h. used in plant tissue culture
Plant tissue culture
structure effects a. promotes cell growth b. ripening in some fruit c. leaves to abscise d. chlorophyll to bleach e. flower pigments to fade
Abscisic acid structure effects a. inhibits cell growth b. make buds & seeds dormant c. stomates to close Frederick Addicott
Brassinosteroids discovered in 1970 (J Mitchell & others) involved in: cell division, cell elongation, vascular development, seed germination, light responses
Day-neutral plant grafted to long-day plant Both plants flower Long-day induction (short night) Graft “Florigen”
Photoperiodism (long-night) (short-night) Also: intermediate- day plants day-neutral plants
Phytochrome Proteins that change shape
Order of red & far-red illumination affects lettuce seed germination
Etiolation
Cryptochrome : a blue light sensor (protein structure) Blue light
Circadian rhythms eg: sleep movements
Necrotic lesions
Jasmonic acid
salicylic acid methyl-salicylate