HORT301

Phytohormones

Phytohormones are• Naturally produced in plants• Chemicals regulating plant growth,

development and differentiation• Active at low levels • Present in several major classes:

a. Auxinsb. Gibberellinsc. Ethylened. Cytokininse. Abcisic acidf. Brassinosteroids

Gibberellic acid (GA)

Gibberellic acid (GA)

• About 136 GAs with structural similarity

• Only a few are “active”: e.g. GA1, GA3, GA4, GA5 and GA7

GA biosynthesis pathway

Sumagic (Uniconazole-P)

Mutation in dwarf pea

Ultradwarf:No GAs

Dwarf:Contains :GA20

Traces of GA1

Tall:Contains:GA1

Effects of GA on growth

Experiment A+B: Effect of GA/GA inhibitor on pea growth

GA or Control solution GA inhibitor or Control solution

•Label pots (group and lab number, treatment)•Measure internode length of 2x 5 dwarf and 2x 5 tall pea plants

•Measure internode length of 2x 5 dwarf and 2x 5 tall pea plants again after 2 weeks in class (MONDAY Oct. 5th)

Treat dwarf plants with GA or Control solution

Treat tall plants with GA inhibitor or Control solution

Auxins

in roots

in stems

Auxin

Effects of IAA on segment elongation

Acid growth hypothesis

Experiment C: Effect of auxin/pH on segment growth

•Cut maize seedlings in exactly 1 cm long segments using a razor blade (15x)

NOTE: Do not let the cut segments dry out!

•Label each dish

•Place five sections in a Petri dish containing either A) IAA (Auxin) solutions of 10-4MB) low pH water, pH 4.5C) neutral pH water, pH 7.0 (control)

•Incubate overnight in the dark.

•The next day (Sept. 22nd) measure the total length of all segments after incubation

•Calculate mean value and standard deviation. Compare the segment length of each treatment

Ethylene

Experiment D: Effects of ethylene on soybean seedlings

1

2

3

“Banana”

•Measure the height of the plants

•Place one pot each in a bag a) With a banana b) With a banana in a GreenBag c) Without a fruit

•Wait four days and come back to measure plant height again (FRIDAY Sept. 25th)

Todays experimental planGA treatment of dwarf mutant in pea

Measure length of 2x 5 pea plantsApply GA or Control solutionMeasure length of plants again after 2 weeks (MONDAY 5th)

GA inhibitor treatment of pea plantsMeasure length of 2x 5 pea plantsApply GA biosynthesis inhibitor or Control solutionMeasure length of plants again after 2 weeks (MONDAY 5th)

Auxin treatment of maize seedling segmentsCut maize seedlings in 1cm segments (15x)Place segments in IAA, low pH or Control solution Measure length of segments the next day (TUESDAY 22nd)

Ethylene treatment of soybean seedlingsMeasure length of 3x 5 soybean plantsPlace pot with 5 plants in bag with banana, wrapped banana or no bananaMeasure length of plants again after 4 days (FRIDAY 25th)

Pipettes

P1000

P200

P20

1000uL = 1ml

Use for: 200-1000uL

200uL = 0.2ml

Use for: 20-200uL

20uL = 0.02ml

Use for: 2-20uL

Map of HLA greenhouse

Tissue culture lab

Zone 21

ENJOY! Ask, if you have a question