Thursday, 7 February 2013


Occasionally when a plant species is difficult to propagate with traditional methods or in danger of extinction, and in many cases very often both, we must place our faith in science and the lab-coated coves initiated in such sorcery! Micropropagation is the growing of plants from seed or tiny pieces of plant tissue in sterile, laboratory conditions, and is utilised to cultivate those dreadful nuisances that are indifferent to a tray of John Innes and a bit of bottom heat. Kew’s Micropropagation Unit was set up in 1974 and produces thousands of plants each year to repopulate endangered species in a series of labs dedicated to this cultivation.
Orchids are one of the success stories at Kew, with this plant family in particular need of specialist techniques. Although they often produce thousands of seeds orchids rely upon fungi in the soil for germination, as theses dust-like seeds lack an endosperm, the part of a seed where a small food store powers the initial stages of germination, before the first leaves are unfurled and photosynthesis becomes the main engine for plant growth. The soil fungi form a symbiotic relationship with the tiny seed, laying on the food that enables germination! This happy matrimony is undoubtedly heart-warming, but from a propagation perspective is insanely difficult to recreate in the potting shed, needing the usual temperature and moisture requirements plus that blasted fungi. As usual science holds the key with micropropagation enabling germination without fungus, in a process called asymbiotic germination that provides all of the nutrients that the fungus would normally supply. This propagation usually does not involve soil, but instead various cocktails of sugars, minerals and vitamins solidified in agar jelly, which holds the concoction together and gives the plants something to root into. The development and success of these techniques has resulted in the saving of species such as the beautiful Lady’s Slipper Orchid, Cypripedium calceolus, which had been reduced to one single specimen left in the wild but was repopulated and reintroduced in a collaboration between Kew and English Nature!
Cryopreservation is used to store plant tissue and seeds, freezing material at -196°C
(-320°F) in these sealed tanks with liquid nitrogen!

Tiny orchid seed is smeared on to the agar jelly mixture

Sincere apologies for the quality of this image, but looking down the lens of a microscope we can see thin grains of orchid seed and the round, swelling seed that has already began to germinate

Eventually roots and shoots develop from the germinated seed

Seedlings are ‘potted on’ to glass jars, where they continue to develop before eventually being finally transferred to traditional soil potting mixtures and then reintroduced to the wild!

Micropropagation does not just involve seeds; here new shoots are developing on a miniature cutting

Some species are not terribly fond on the agar jelly cocktails, so a rough plug mixture is used instead

Even succulents can be raised with this method!

Carnivorous plants, Dionaea muscipula, can be seen here. As the nutrients in the agar mixture are used up, yellowing leaves on the plants indicate the time to pot on to a soil based medium

It’s propagation, but not as we know it!
A little off the beaten track, but I hope this offers an insight into some of the madness going on here at Kew! As an aside the good eggs over at Tweed Pig have kindly featured me in their ‘pin-up’ series, please click here to take a look.


Doc said...

Absolutely fascinating Bertie and congratulations on the pin-up.

Share my Garden said...

I've just had a peek at the Tweed Pig and have to say how very dapper, Bertie! I shall have to check out your suppliers and bring Himself a bit more up to the mark. I miss your wonderful images of Hidcote but imagine that Kew is an exciting place to be. And you'll be able to pop into a palm house if you need a warm up!. No gardening going on here as yet other than clearing up dead matter from the borders but I'm itching to get a spade into the soil.

Anonymous said...

So far over my head! And so fascinating!

Wife, Mother, Gardener said...

Loved seeing the microprop photos! And interesting to hear more about the process in Bertie-speak.

When my hubby & I watched Hidcote, we kept going back and forth during the early shots: "It's Bertie! Maybe not...umm... yes, it has to be... I think." Funny to try to identify someone from a thumbnail photo :)

Bertie Bainbridge said...

Greetings all! Glad this brief science detour was enjoyed.