Wednesday, October 31, 2012

Tree's leaves genetically different from its roots

Populus trichocarpa (black cottonwood; also known as western balsam poplar or California poplar) is a deciduous broadleaf tree species native to western North America, and it was the first tree species to have its genome sequenced and published in 2006.

This tree can also reproduce via vegetative reproduction. This means that these trees can cl
one themselves to produce offspring that are connected to their parents by the same root system. Now, after the first genome-wide analysis of a tree, it turns out that the connected clones have many genetic differences, even between tissues from the top and bottom of a single tree. And these variations within the tree could be as large as variations across unrelated trees, thus challenging the old paradigm that evolution only happens at the population level and not the individual level. (Source 1)

Mutations that occur in cells other than sperms or eggs are termed as somatic mutations, and although these mutations were well known, until recently we did not have a genome-wide study of them, and no one had catalogued the total number of mutations.

Biologists (detailed in Source 1) collected samples from 11 parent-clone sets of black cottonwood parents and their connected offspring. After comparing these sets, scientists found 188,406 mutations that were unique to just one tissue sample, differing even from other parts of the same tree.

The finding also has implications in cancer research, as recent research suggests that separate parts of the same tumour can build up distinct genetic mutations independently, meaning that single biopsies give only a narrow view of the tumour’s diversity. (Source 2)

Source:
1) http://www.nature.com/news/tree-s-leaves-genetically-different-from-its-roots-1.11156
2) http://www.nature.com/news/biopsy-gives-only-a-snapshot-of-tumour-diversity-1.9998
3) http://www.na.fs.fed.us/spfo/pubs/silvics_manual/volume_2/populus/trichocarpa.htm

Image:
http://www.blackfootnativeplants.com/trees/blackfoot-native-plants/
Tree's leaves genetically different from its roots

Populus trichocarpa (black cottonwood; also known as western balsam poplar or California poplar) is a deciduous broadleaf tree species native to western North America, and it was the first tree species to have its genome sequenced and published in 2006. 

This tree can also reproduce via vegetative reproduction. This means that these trees can clone themselves to produce offspring that are connected to their parents by the same root system. Now, after the first genome-wide analysis of a tree, it turns out that the connected clones have many genetic differences, even between tissues from the top and bottom of a single tree. And these variations within the tree could be as large as variations across unrelated trees, thus challenging the old paradigm that evolution only happens at the population level and not the individual level. (Source 1) 

Mutations that occur in cells other than sperms or eggs are termed as somatic mutations, and although these mutations were well known, until recently we did not have a genome-wide study of them, and no one had catalogued the total number of mutations.

Biologists (detailed in Source 1) collected samples from 11 parent-clone sets of black cottonwood parents and their connected offspring. After comparing these sets, scientists found 188,406 mutations that were unique to just one tissue sample, differing even from other parts of the same tree. 

The finding also has implications in cancer research, as recent research suggests that separate parts of the same tumour can  build up distinct genetic mutations independently, meaning that single biopsies give only a narrow view of the tumour’s diversity. (Source 2)

Source: 
1) http://www.nature.com/news/tree-s-leaves-genetically-different-from-its-roots-1.11156
2) http://www.nature.com/news/biopsy-gives-only-a-snapshot-of-tumour-diversity-1.9998
3) http://www.na.fs.fed.us/spfo/pubs/silvics_manual/volume_2/populus/trichocarpa.htm

Image: 
http://www.blackfootnativeplants.com/trees/blackfoot-native-plants/

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