Finally getting the hang of it!

For those of you who have been following my frustrated attempts to grow enough parasitic Striga gesnerioides to harvest seed for my depleted stocks.... I may have finally turned the corner!

My previous attempts to do this essentially involved mixing large quantities of my remaining Striga seeds with sand, putting this into pots and transplanting young, susceptible tobacco hosts into these. The first attempt failed completely, and whilst I had more success with the second ( see blog post for 3 rd August), less than fifty shoots emerged for the thousands of seed that went in. Not nearly enough seed to even fill the base of a glass vial, never mind filling it to the brim!

The problem is,this was all done very unprecisely. It essentially trusted to luck that by the time the Striga seed had preconditioned for long enough to break their state of dormancy, the young tobacco would have grown enough roots so that there would be one in the proximity of each seed to infect. Many of the seeds may well have germinated underground, but, finding nothing to attach to, withered and died. Striga seeds are so minute - like dust - that they do not have enough reserves of their own to grow without a host. And given that all of this happens underground, it was impossible for me to tell what was going on!

So I tried an experiment. When I infect my Arabidopsis plants with Striga for the main experiments of my PhD, the host plants are grown in square petri dishes ( rhizotrons ) with the roots pressed against the lid. This means I can take the lid off and apply the parasite seed directly onto the roots using a paintbrush, so the seed will germinate and infect the host straight away. So I decided to try this with the tobacco. After squashing some young seedlings into rhizotrons and leaving them a week or so to adjust, I then liberally painted the roots with preconditioned Striga seed. I let another week or so pass to give the seed time to properly attach, then transplanted the  seedlings into pots. Then I wished them a fond farewell and left for my holiday! Which was, incidentally, absolutely WONDERFUL - a complete break from work,with the nearest I got to plants being the picnic lunches I enjoyed in the Giardini by St Mark's square....

Meanwhile, my good colleague Emily was looking after the infected tobacco. The most I was hoping for was 20 shoots on each plant. But when I returned, I was in for a surprise!

It was a Striga EXPLOSION - a forest of shoots thrusting up around each host, packed so closely together it was impossible to count. There must be at least sixty shoots on each plant with more coming up every day! So many that they have left the tobacco hosts in a sorry state - shrunken, wrinkled and yellow a due to all the nutrients and water they are siphoning off. But it looks like I can finally stop worrying about my seed!

So all I have to do now is leave them to it and let the shoots flower, form seed capsules and then dry out so I can harvest them.  I'm beginning to see why there is so much fuss about 'Precision Agriculture' - sometimes it really does pay not to leave things to chance!

A very poorly tobacco...