Genome complexity: epigenetic insect champion (Introduction)

by David Turell @, Tuesday, May 02, 2017, 17:50 (785 days ago) @ David Turell

This aphid seems to be able to adapt to any plant to pestify:

http://www.the-scientist.com/?articles.view/articleNo/49219/title/Uncovering-the-Secret...

"While most aphids are only able to colonize one or a few plant species, the green peach aphid (Myzus persicae) isn’t picky about its food. The polyphagous, or generalist, pest can feed on more than 100 species from around 40 different plant families. “Polyphagous insects always have a host somewhere, so they can keep going and can become massive pests,” says Saskia Hogenhout.

***

"Hogenhout, Mathers, and colleagues recently set out to see what gave M. persicae its remarkable ability to colonize such a huge variety of plants. To do so, they first sequenced M. persicae’s genome and compared it to that of the pea aphid, Acyrthosiphon pisum, a specialist that only occupies a few host plant species.

"Much to the authors’ surprise, A. pisum had a genome nearly double the size of M. persicae’s. “[This] is very surprising and counterintuitive,” You might expect that this aphid, with its very large host range, has a larger complement of genes that might allow it to feedsays Chris Bass, a University of Exeter professor who was not involved in the work. says Chris Bass, a University of Exeter professor who was not involved in the work. “You might expect that this aphid, with its very large host range, has a larger complement of genes that might allow it to feed on a different number of hosts—but it looks like the opposite is actually the case.”

"The group then investigated the transcriptional changes that occurred when M. persicae colonizes a new host. From this analysis, they found that gene expression changes in two gene families, cathepsin B and RR-2 cuticular protein, occurred rapidly—a mere two days after the aphids were transferred to a new plant host. When the researchers generated transgenic plants that could knock down cathepsin B gene expression in the insects, the aphids’ ability to survive and reproduce on a new host was significantly reduced.

"The team also discovered that the genes involved in host-switching were older gene duplicates that arose during aphid evolution. “It was as if Myzus persicae was able to take pre-existing genetic diversity in the genome and then just fine-tune the expression of those genes to be able to colonize a new host, rather than having more duplicated genes to colonize these different plant species,” Mathers says.

***

"According to Hogenhout, it’s possible that the ability to transfer rapidly between hosts helps M. persicae develop resistance to pesticides as well. If a pesticide is applied to a crop, these aphids can quickly move away to another crop after only experiencing sublethal doses of pesticides. A few years ago, a group at Imperial College London reported evidence for this type of mechanism."

Comment: This insect is a champion of epigenetic gene expression/transcription changes. Did it develop this ability by itself or was it given this ability? It is still the same species. Closely related species do not this ability. It is hard to explain by a blind evolutionary process.


Complete thread:

 RSS Feed of thread

powered by my little forum