Natures wonders: parasitic plants steal food & genes (Introduction)

by David Turell , Thursday, February 02, 2017, 01:10 (2850 days ago) @ David Turell

They attach by the roots:

http://www.the-scientist.com/?articles.view/articleNo/48024/title/This-Parasitic-Plant-...

"Lophophytum is a holoparasitic plant, meaning that it has forsaken photosynthesis and is completely reliant on its various hosts for survival. In canopy-darkened South American jungles, the inconspicuous root parasites send spikes of inflorescence upward through the soil while their roots tap into the nutrient supply of plants such as the wilco tree (Anadenanthera colubrina). But as it turns out, Lophophytum has been stealing much more than just nutrients from its unsuspecting hosts: it has also been snatching their mitochondrial genes, and tossing out many of its own in the process.

"Careful analysis of the Lophophytum mitochondrial genome sequence, which is about 820,000 base pairs long, revealed 56 genes (44 protein- or RNA-encoding genes, some in multiple copies), which is unremarkable. But what is remarkable about these genes is that at least 37 of them, including 35 protein-coding genes, were acquired via horizontal gene transfer from the plants that Lophophytum parasitizes. In other words, Lophophytum has swapped almost all its native mitochondrial genes for their foreign equivalents, which is a bit like replacing all the appliances in your kitchen with those from a neighbor­’s kitchen.

"Horizontal gene transfer is not uncommon in parasitic plants like Lophophytum, which form vascular connections with their hosts, making it easy for them to pilfer water and nutrients. But this open flow from host to parasite also opens the door for the movement of DNA and even entire mitochondria.

***

"Finally, a small fraction (0.6 percent) of the Lophophytum mitochondrial genome is made up of chloroplast-derived DNA. But, again, these chloroplast sequences appear to have been acquired from the host rather­ than from the Lophophytum chloroplast. In fact, not a single native chloroplast gene was found in the more than 6.5 billion base pairs of Lophophytum sequencing data, which was derived from total cellular DNA, suggesting that this parasite might have lost its own chloroplast genome outright. The complete forfeiting of plastid DNA is an extremely rare event, but it is believed to have occurred in the holoparasitic plant Rafflesia lagascae—which bears so-called “corpse flowers,” so named for their fly-attracting putridity—as well as in the nonphotosynthetic green alga Polytomella.

Comment: Parasites can take over plants in many ways as this shows. I wonder how it all happens. Not stepwise I would think. You either are parasitic or not. Half parasitic?