It seems ironic that, although these parasites run rampant in the countries they affect, it can be surprisingly tricky to grow them in this country, even under the controlled conditions the lab and growth room allow. Nevertheless, the Scholes lab has got this down to a fine art, with precise timings, meticulous watering regimes, accurate chemical concentrations of germination stimulants...etc. I have grown Arabidopsis (thale cress; the model organisms of the plant science world, with the most heavily annotated genome of any plant), Wheat and Sorghum before but working on multiple systems at once is a new challenge. First there are the crops themselves. I have successfully managed to germinate rice seedlings and am growing these up to infect with Striga next week. The problem is, these plants can take up a fair bit of space...hence the rhizotron system. Rather than growing the seedlings in pots, the roots are trained into large, flat square petri dishes packed with vermiculite (which looks like an inedible form of muesli); these are then covered in foil to simulate below ground conditions. The petri dishes are packed together in trays, the young leaves poking out of a hole at the top, each with a "dripper" for irrigation. The Striga seeds, meanwhile, are prepared in an incubator in the lab; like Orobanche, these require a few weeks of "pre-conditioning" - being coddled in warm, moist conditions. This makes them responsive to germination stimulant. Because parasite seeds are tiny (no, really, miniscule, like dust!), they have little reserves so have developed a clever strategy where they only germinate in the the presence of a suitable host that they can rapidly infect. To do this, they have evolved the ability to recognise chemical compounds naturally secreted by hosts in the root exudates, called "germination stimulants". In the case of Striga, these compounds are classed as "Strigolactones", which also have a role as a plant hormone in the host, to regulate branching. The parasite seed then germinates and follows the concentration gradient of the germination stimulant to reach the root. Synthetic strigolactones are available; we use one called GR24 to pre-germinate the seeds before infecting the plant. This is done by prising the lid off the rhizotron and literally "painting" the seeds over the roots. The poor rice plant hasn't got a chance. At this moment, my Striga seeds are still preconditioning in the incubator and my rice plants propped up in their rhizotrons in the controlled growth room chamber, ready for infecting next week. I mustn't forget I'm on water barrel duty this coming week - if everyone's plants die from drought it will be my fault!
Meanwhile, I am constantly surprised at how much there is going on (perhaps Durham was a bit of a small University in that respect...)... it can be a bit overwhelming at times and I had to be disciplined in NOT attending all the talks at the book festival. I did catch a highly entertaining talk on science communication given by Ed Young, famous for his Blog "Not exactly rocket science" - it certainly gave me a few ideas for shaping this blog. The Animal and Plant Sciences Department, meanwhile, is keenly committed to public outreach, with a highlight this term being the "Christmas Time Lecture" where close on a thousand young school children are treated to a "Royal Society Lecture" experience before hands-on demonstrations and other entertainments. Past topics have included Birds and Dinosaurs and this year Plants have the starring role... I'm keen to be involved but with this literature review hanging over me, I'm not sure I will be able to spare the time to organise a demonstration so perhaps it will have to be as a steward. It will be worth it to see the unveiling of RoboPlant!