Biology 11–12 · Year 12

Cloning cauliflower by tissue culture on sterile medium

Module 6: Genetic Change (Biotechnology; Genetic Technologies: whole organism cloning)

PracticalMedium risk

School laboratory, not for home

In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

The idea

A few plant cells on a sterile nutrient medium can regrow a whole plant because plant cells keep the capacity to form any tissue, which is the basis of micropropagation.

Safety card

Medium riskA teacher supervises

Setting: In a school laboratory, with a teacher supervising, under the school's risk assessment. Not for home.

Hazards

Sodium dichloroisocyanurate is toxic, bleaches clothing and releases chlorine vapour
Scalpels
Contaminated cultures may grow moulds
Ethanol is flammable

Controls

Safety glasses, gloves and a lab coat when handling the sterilant; do not inhale its vapour; staff make up the solutions
Cut on a tile away from the body; blades to the sharps bin
Never open a contaminated jar; autoclave for disposal
No flames in the room while ethanol is in use

Note

Sterilising solutions and aseptic work: NSW Department of Education Chemical Safety in Schools package (https://education.nsw.gov.au/content/dam/main-education/asset-management/chemical-safety/1._Section_1_-_General_information_for_all_staff.pdf) and RiskAssess (https://www.riskassess.com.au/).

What you need

Fresh whole cauliflower (not ready-cut pieces, as the SAPS notes specify)
Culture medium in small sterile jars: MS medium with 20 g/L sucrose, 2.5 mg/L kinetin and 0.032 percent sodium dichloroisocyanurate, made by the technician in a microwave without an autoclave, following the SAPS technical notes based on the Royal Botanic Gardens Kew method
Sodium dichloroisocyanurate (SDICN) solution 0.5 percent: one 4 g Milton sterilising tablet, which is 19.5 percent SDICN by mass (about 0.8 g), in 160 mL water, as the SAPS notes give; with another brand, use tablets giving 0.8 g of SDICN per 160 mL, because own-brand tablets are often smaller, as the notes warn: 10 mL in a screw-cap bottle per pair for the explants, and a capped jar for standing forceps and scalpel
Forceps and scalpel soaked in the SDICN solution for at least 20 minutes beforehand; white tile; Petri dish; beaker for waste solution; 70 percent ethanol for wiping the bench
Safety glasses, disposable gloves and a lab coat; a warm, lit windowsill or light bank

How to do it

Wash hands and arms, wipe the bench and tile with 70 percent ethanol, and work on a draught-free bench without leaning over the materials.
Cut small pieces of curd 3 to 5 mm across, place them in the 10 mL of SDICN solution, cap and swirl, and leave for 15 minutes; no rinse is needed because the gentle sterilant stays on the explants and is also in the medium, as the SAPS notes explain.
With forceps taken from the SDICN jar, transfer one explant onto the medium in each jar and replace the lid at once.
Incubate in a warm laboratory near a window or light bank; examine each jar weekly without opening it and record contamination, greening, shoots and roots.
Compare explants of different size, from different parts of the head, or given different sterilisation times, by the percentage that green and grow and the percentage contaminated.
Hand contaminated jars to the technician unopened for disposal by autoclaving.

What you should see

Greening and growth of uncontaminated explants should be visible within 10 days (the SAPS figure); over the following weeks some explants form shoots and then roots, each an identical clone of the parent head. A proportion of jars may show fungal or bacterial growth, and these are discarded unopened. The learner knows it worked when at least some explants have turned green and grown on a clear medium.

What changes

What you change: explant size or position on the head, or sterilisation time
What you measure: percentage of explants forming shoots, and percentage contaminated
What you keep the same: medium batch
light and temperature
time
aseptic technique

Common misconceptions

Each of these ideas is wrong, and the activity is a chance to test it.

Only seeds or cuttings can make new plants; a few cells can regrow the whole organism.
Tissue culture changes the plant's genes; it copies them.
Contamination means the explant was diseased; it means microbes from air or surfaces reached the rich medium.

Curriculum references

The NSW syllabus outcomes and Australian Curriculum v9 codes this activity supports. They are references, not a verified or complete curriculum alignment.

Biology Stage 6 Syllabus (2017), current: Year 11 taught to the end of 2026 and Year 12 to Term 3 2027BIO12-13 BIO11/12-7
Biology 11–12 Syllabus (2025), Year 12 focus area Biotechnology; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12-04
Biology 11–12 Syllabus (2025), Year 12 Working scientifically; new syllabus not yet taught: Year 11 from Term 1 2027, Year 12 from Term 4 2027BI-12WS-03 BI-12WS-07
Australian Curriculum v9No Australian Curriculum v9 code is listed.

Sources

The pages the author read to write this activity.

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