You’ve got to hand it to plants, when it comes to reproduction, they’ve exploited all manner of means to overcome the problem of being stuck in one spot. We often think of ourselves as exploiters of plants, when it’s often the other way around. Up until Thomas Crapper’s most famous invention (the flushing toilet), our ancestors picked, plucked and munched their way through many a plant ovary (fruit to the layman), and dutifully provided the plant with the means to spread its seeds on farther shores (or behind a handy bush!). Of course this is all a bit of a segue into today’s fun. Under the careful eye of the eminently wise horticulturist and postdoc, Caroline Elliott-Kingston, we cajoled some shy pollen grains into achieving their life destiny. What pollen lack in choice of mate, they sure make up for in speed. Within a half an hour of depositing our hopeful chaps (a.k.a pollen grains) onto the petri dishes they were speeding forth, growing out their tubes and seeking out the waiting ovule, which in this case unfortunately, did not exist. And here in lies one of the big problems of the plant kingdom. How do you get the right sperm and eggs to meet to ensure the continuation of your species? Most people would be familiar with the means by which pollen is dispersed, wind and insects. But possibly less familiar is the mechanisms plant uses to make sure that the right pollen is attracted to the right stigma. The truth is that pollination is a haphazard, somewhat random process whereby plants will catch pollen from many species and with some luck and genetic selection some or all of the ovules will be fertilised.
Looking after the boys in the laminar air-flow hood!
Just for kicks we drop our pollen into a number of nice and not so nice solutions, metaphorically speaking. We wanted to discover the magic cocktail to get the best growth from the pollen grain. As it happens, a buffered calcium solution came out tops among some serious bad guys i.e. aluminium and lanthanum. Calcium has a well-documented effect in ion-gated channels in animals and it seems its power to control membrane activity extends to plants as well. Our calcium-soaked grains were very obliging in producing beautiful, directional tube growth. Success!
A short you tube video on pollen tube growth
An article on some possible mechanisms of pollen selection