Wednesday, February 12, 2014

Bar bet of the day: does pollen have chloroplasts?

Here's some botany 101 we've been chewing on...

Can you sequence chloroplast DNA from pollen?

For gymnosperms, pollen is transferred via the pollen, so yes in them.

But in angiosperms, it's maternal, so no.

But, Wikipedia says "Pollen itself is not the male gamete.[1] Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell containing two nuclei: a tube nucleus (that produces the pollen tube) and a generative nucleus (that divides to form the two sperm cells)."

That means it should be yes.

Yet, we asked one botanist and they said,

"mostly you should NOT be able to find plastid DNA in pollen (see papers like Corriveau et al., 1990, Plastid DNA is not detectable in the male gametes and pollen tubes of an angiosperm (Antirrhinum majus) that is maternal for plastid inheritance."

Then we asked another, and they said

"A pollen grain represents the mature male gametophyte. It is a multicellular product of mitosis. Absolutely it contains a chloroplast genome... It's just that (usually) the cp genome from the pollen is excluded during zygote formation...."

That would suggest yes.

We haven't settled this bar bet yet.

Once we do, we should know how best to use molecular tools to identify pollen...


  1. It has to be present, as demonstrated by "Inheritance of chloroplast DNA is not strictly maternal in Silene vulgaris (Caryophyllaceae): evidence from experimental crosses and natural populations."

  2. I've read this one too. It still seems unclear whether cp DNA sometimes slip into pollen or whether they are consistently there.