Talmudic Question #35

In Twisted Bacteria, César Sanchez poses the question: Why don't plants have any chlamydial symbionts? He proposes several possible answers and invites further speculation. We suggest you go to his website and post your comments there.

Comments

[stan zahler]

I guess I'm not so sure that chlamydia are tender. Psittacosis gets around from bird to bird (and occasionally bird to humans) in aerosols, which have to be tough environments especially as they dry out. Getting through plant cell walls is trickier. Has anybody ever tried to infect scratched Arabidopsis leaves with a lot of chlamydia?

-- stan zahler

[Epicanis]

(And, yes, I've tried posting at the "twisted bacteria" blog several times now. Blogger is once again erroring out on comments and losing them. Ugh.)

[Epicanis]

I would tend to suspect that it's because Chlamydia-type bacteria are substantially less environment-resistant that viruses.

As far as I know, all plant viruses require physical damage to the plant cells to achieve an initial infection (though some or all of them can then pass viral material from cell to cell once infection is established). I suspect that due to the cell wall, the same would be true of endoparasitic bacteria like Chlamydia.

Since establishing an infection means hanging around on the surface of either a plant or something that will damage a plant (such as insects or animal claws) for extended periods, I'm guess few or none of these types of bacteria possess that kind of hardiness. I'd further guess that this might have something to do with their tiny size - don't they have an especially small genome? No room for extra "bonus" genes to provide some kind of adaptation like spore formation.