Science 7–10 · Year 9

Cauliflower cloning: tissue culture under aseptic conditions

Science understanding: Biological sciences

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 tiny piece of plant tissue on a sterile nutrient medium can regenerate a whole plant, because its cells keep the full set of instructions; micropropagation, the technology built on this, is used by the Royal Botanic Gardens, Kew to clone endangered plants and in commercial crop propagation.

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
Sharp scalpel
Mould in contaminated vials
Hot agar when the technician prepares the medium

Controls

Safety glasses, gloves and a lab coat when handling the SDICN bottles; do not inhale the vapour
Learners handle the SDICN only if CSIS Appendix A or D lists it in a category that allows student use; otherwise the teacher carries out the SDICN steps and learners cut and plant the explants
Scalpel cuts on the tile away from the hand
Contaminated vials never opened; disposed of by the technician
Medium cooled to about 45 °C before the sterilant is added, in a well-ventilated area, as SAPS directs

Note

Chemicals and heat: follow the NSW Department of Education Chemical Safety in Schools (CSIS) package (section 1, general information for all staff) and complete a RiskAssess risk assessment before the lesson. Confirm the CSIS category of sodium dichloroisocyanurate in CSIS Appendix A or D before learners use it: under CSIS Section 1 (Figure 1.7-3) a chemical not listed in Appendix A or D is treated as category N, for demonstration by approved teachers only, until an approved (Code 1) user completes a site-specific risk assessment.

What you need

A fresh, whole cauliflower (not ready-cut pieces)
Vials of sterile plant growth medium (Murashige and Skoog medium, 20 g/L sucrose, 2.5 mg/L kinetin and 0.032 % sodium dichloroisocyanurate in agar), prepared by the technician as the SAPS cauliflower cloning notes describe
0.5 % sodium dichloroisocyanurate (SDICN) solution made from sterilising tablets, 10 mL in a capped bottle per pair for the explants and a small jar for the forceps
Forceps, scalpel, white tile, Petri dish, 70 % ethanol and paper towel for wiping the bench, a waste beaker, and a well-lit spot

How to do it

Wash hands, stand the forceps in the SDICN jar and wipe the bench with a little 70 % ethanol.
Cut a small mini-floret from the cauliflower curd and slice it on the tile into explants 3 to 5 mm across.
Put the explants in the bottle of SDICN, cap it and swirl gently for 5 seconds every 2 to 3 minutes for 15 minutes, as the SAPS student sheet directs; the SDICN is not rinsed off. Learners do this step only where the CSIS category of SDICN allows student use; otherwise the teacher does it.
Strain the liquid into the waste beaker, then with the forceps press one explant stalk-end down into the medium in each vial. Cap and label with name and date, without leaning over the work.
Stand the vials in a warm, well-lit spot and inspect weekly for four weeks without opening: record greening, shoot and root growth, and any fuzzy or cloudy contamination.
Calculate the percentage of vials with growth and the percentage contaminated across the class.

What you should see

The SAPS student sheet says greening of the explant and growth should be visible within 10 days, and SAPS describes this updated method as generally very reliable when followed correctly, so most class vials are expected to grow. Contaminated vials show fuzzy mould or cloudy medium and are discarded unopened. The learner knows it worked when their vial is green and clear, and the class contamination rate is low.

What changes

What you change: Explant source (surface of the floret versus stalk), or light versus dark
What you measure: Percentage of explants growing at four weeks
What you keep the same: Sterilisation time (15 minutes in 0.5 % SDICN)
Medium
Explant size
Temperature

Common misconceptions

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

Only seeds can grow a new plant.
Cells lose their instructions when they become part of a floret.
A clone is a copy made by a machine; here it is a plant grown from a parent's cells.

Curriculum references

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

Science 7–10 Syllabus (2023)SC5-GEV-02 SC5-WS-03 SC5-WS-04
Australian Curriculum v9AC9S9U02AC9S9I02AC9S9I03AC9S9H02

Sources

The pages the author read to write this activity.

All Concept Studio activities