Introduction

Lilies, of many different varieties, have been and continue to be an extremely popular flower (both in cut floral arrangements and for landscape/garden/indoor pots/etc. decoration). The Lilium longiflorum, or Easter Lily, is only one of the many extremely popular varieties of lilies available today.

One of the most successful, albeit time consuming, methods of growing/creating lilies for selling purposes is a form of vegetative propagation called tissue culture. This process, as will be described in the following section, can produce up to two million bulblets in approximately two years. However, it is important to note that, despite the sterilized cloning process, some mutations have evolved, so a clone might be in some way different from original plant. However, this is typically not the case.

Tissue culture makes large quantities in a short time and is favored by many commercial growers (not usually the local gardener). It has a higher cost than scaling (another one of the many forms of lily propagation, many of which can be found here), so usually only newest and most unusual clones chosen for this method. The process produces virus free plant material. This is done by testing for lily viruses with ELISA (enzyme-linked immunosorbent assay) when the tissue is  initiated into culture. If a virus is detected, meristemming (“a process in which very tiny pieces of rapidly growing meristem cells are removed, cultured and retested… until virus free tissue is found” (Cummings)) will eliminate it. This process is repeated several times by the plant breeder/commercial grower over the course of many months, costing a significant amount of time and money. This large money input into developing the bulblets, however, is made worth it by the justly increased price per bulb. It is important to note that these bulbs are not immune to those viruses and can get reinfected.

Tissue culture has even been used to bring back endangered wild species of lillies. However, because all the plants produced are clones of the parent, the genetic diversity of the particular plant species decreases. Propagating seeds allows for at least some differenced in DNA (allowing for differences in color, height, vigor in certain conditions, etc.). Genetic diversity can allow a species to survive over generations, overcoming diseases, climate changes, etc..

How-To

Supplies Needed: 

• soap and water
• a sterile/controlled (in temperature, humidity, etc.) environment (like a laboratory with an incubator, preferably even with a hood to work in)
• a sterile nutrient medium with growth hormones
• bulb scales, stem segments with an internode, or flower buds
• 10% solution (household bleach and water)
• sterilized cutting utensil
• sterilized forceps
• sterile vessel (petri dish, test tube, etc.)
• plastic wrap
• sterile gloves (optional)

The Preparation:

All materials must be sterilized in some thorough fashion before beginning this process.

To optimize rapid cell division and differentiation the tissue will need to be placed in some form of media. This can be searched for and purchased online (here for example, where even plant propagation kits can be purchased), but the following is a “recipe” used in a lab experiment for such a tissue culture process:

“0.22% gelrite-gelled basal medium containing MS basal medium (Murashige and Skoog, 1962), myo-inositol (100 mg/l); niacin (0.5 mg/l); pyridoxine HCL (0.5 mg/l); thiamine HCL (0.1 mg/l); glycine (2.0 mg/l); casein hydrolysate (1 g/l); sucrose (30 g/l). Supplement with 2, 4-D (3 mg/l) and BA (0.25 mg/l) and the pH of the media was adjusted to 5/7 with 1 N KOH or 1 N HCL prior to autoclaving at 121 degrees  for 15 minutes”

Place the media in the tubes/vessel and cover them, preparing you for the following steps.

The Cutting:

With a sterile cutting utensil, take either bulb scales, stem segments (with an internode), or flower buds off of your desired plant.

The Process:

First, rinse your cutting in soapy water, swirling it about in the cup to ensure thorough coverage. The place the cutting in the 10% bleach solution for 25 minutes. Stir the cutting(s) in the cup every so often to ensure that it is soaked/covered thoroughly. The rest of these steps ought to be done under a sterile/ freshly cleaned hood to ensure that the cultures do not become contaminated. It is also best to work quickly and keep your face/breathing away from the cultures/materials/etc.. Remove the cutting, rinsing it with distilled water. The rinsing is best done by dipping and swirling the cutting into three separate cups of distilled water one at a time to ensure that the bleach/debris/etc. has been washed off.  On a sterile plate/surface cut your cutting into segments of approximately 5mm squares (known as the explants). On scales, use the portion of the scale closest to the basal plate (which produces bulblets). Place these squares in a petri dish or test tube with the medium in it. Secure the vessel with plastic wrap around the outside, tightly secured.

Storage: 

Store your cultures in a dark, sterile environment at 70 degrees F (21degrees C). If not contaminated, bulbets will form in a few weeks. Over time the bulblets will form in huge quanitities, and they will get to a marketable size in approximately two years.

Transplanting:

When your bulblets are large enough, they can be put into pots with potting soil to root. rooting. Keep these plants in a shady area and well misted (gradually reducing the amount of mist), as they acclimate to the real-world conditions. They can then be planted to flower, this is best done in the late summer or first in spring (helping the plants to become hardier more quickly) or indoors.

Conclusion

Lilies like the Easter lily are a fun, interesting, and gorgeous plant to grow. One means of growing/propagating your favorite lilies is through tissue culture. This intensive process is used mostly by commercial growers (and is somewhat difficult to do at home), as well as is time consuming and often costly, but it can yield large, virus-free quantities of lily bulbs. Try this out as a neat in-home experiment, see how your results fare!

Works Cited

Bridgen, Mark. “Lilium Spp., Lily.” Plants from Test Tubes: An Introduction to Micropropogation. N.p.: Timber, Incorporated, 2013. 199. Print.

Chang, Chen, Chang-Tesrn Chen, Yu-Ching Tsai, and Wei-Chin Chang. “A Tissue Culture Protocol for Propagation of a Rare Plant, Lilium speciosum Thunb. Var. gloriosoides Baker.” Academia Sinica. N.p., 29 Sept. 1999. Web. 12 Mar. 2014.<http://ejournal.sinica.edu.tw/bbas/content/2000/2/bot12-08.pdf>.

Cummings, Michael. “Lily Propagation Methods.” Mike’s Backyard Garden. N.p., n.d. Web. 15 Mar. 2014. <http://www.mikesbackyardgarden.org/lilyprop.html>.

Hammond, John. “A Brief History of Easter Lilies and the Role of the Beltsville Agricultural Research Center.” Agricultural Research Service. USDA, n.d. Web. 14 Mar. 2014. <http://www.ars.usda.gov/sp2UserFiles/Place/12000000/Partnering/LilySuccess.pdf>.

“Plant Care: Lilies : How to Grow a Day Lily Root From Cuttings & Tissue Culture.”YouTube. N.p., 27 Jan. 2012. Web. 21 Mar. 2014. <https://www.youtube.com/watch?v=T6Z9DKBykVY>.