My Brilliant 'Bonsai' Tobacco!

I must admit, it was with some trepidation that I agreed to my supervisor's plan for my second attempt to bulk up the seeds of my model parasitic plant - Striga gesnerioides - using a susceptible tobacco host. In my first go, the tobacco were grown in the controlled environment rooms, where the climate is set to resemble the tropics. They thrived under such treatment and grew to nearly six foot, but sadly, the parasites failed to survive long enough to flower and set seed. My supervisor declared that it had probably been just a bit too hot in there, so this time I was to grow them in my growth cabinet, where I could keep the temperature much cooler.

Sounds great!

But one problem...

My growth cabinet is...well...not very big. Positively TINY in fact, if you are trying to squash in six foot tobacco. 

My first tobacco plants, in the controlled environment rooms.

But, I was assured the plan would work - 'We've done it before, years ago!'- so germinated several seeds and selected four healthy seedlings to transplant into big, Striga-infested pots. And I waited and watered them and watched nervously as they rapidly stretched towards the ceiling. 

Then - stop! The tobacco plants abruptly stopped growing and burst into flower. In plants, flowering is a key 'decision point' and marks a transition from vegetative to reproductive growth. So they are not going to get any bigger. ( Although some plants produce inflorescences on the side of their stems, each flower head is considered as a separate stem - once the meristem produces a flower, it will no longer grow taller). I was amazed! It was as if they simply knew that they were in a smaller cabinet this time. Plant intuition?

When I asked my supervisor, she explained it all with a single word: 'Light!' I should have known - only last week, I was helping to demonstrate on an undergraduate practical investigating how light conditions during development affect the growth of pea plants. But I hadn't appreciated HOW different the light intensity was - only a sixth of the level which the first tobacco plants experienced. It made me wonder - when we admire the twisted and tortured shapes of mature trees, and wonder at the conditions which caused them to assume such shapes, what part did light have to play? Needless to say, I was very glad that I didn't have monster tobacco plants bursting out of my cabinet...

One of my new 'mini-tobacco' plants, next to my growth cabinet

And it seems, small IS beautiful...for my parasites at least. A single Striga shoot has erupted in one of the pots. I could believe it when my supervisor gave me the news as I had only checked them myself three hours before. It's a shame I didn't leave a camera running as it must have been a dramatic breakthrough! I can only hope it is the first of many. Fingers crossed!

I hope there will be lots more - the first Striga gesnerioides shoot to emerge.

PS I have been doing some writing for the Univeristy of Sheffield's Science in Policy Group's blog - click here to see my review of a talk by Dr Simon Wilcock on how data on ecosystem services should be used to influence policy

http://www.sheffieldscienceinpolicy.com/blog/using-the-ecosystems-approach-to-support-evidence-based-policy-a-talk-by-dr-simon-willcock