All,
With all of the discussion I've been reading about apple production, organic
vs. non-organic, maybe an article like this could bring us a little hope for
the future...
Brian, Sheridan, IN
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A group of researchers from Italy, the US, France, New Zealand, and Belgium
reported in the online edition of Nature Genetics that they have sequenced a
draft version of the domesticated apple genome - a feat that is expected to
lead to a better understanding of the biology of apples and related plants as
well as improved apple varieties.
The team used a combination of Sanger and high-throughput sequencing to tackle
the genome of the Golden Delicious variety of domesticated apple, Malus x
domestica. Based on the genome sequence and comparisons with related plants,
the team concluded that domesticated apple most closely resembles a wild plant
from central Asia called Malus sieversii and is descended from an ancestral
plant that underwent genome duplication within the past 50 million years or so.
Domesticated apple belongs to Rosaceae, the same family as cherry, strawberry,
and rose plants. But apples and other members of a sub-tribe called Pyreae have
far more chromosomes than the rest of the Rosaceae family: 17 compared with the
seven to nine chromosomes found in other Rosaceae plants.
Using a combination of Sanger and 454 GS FLX Titanium sequencing, the
scientists generated sequence covering about 81 percent of the heterozygous
Golden Delicious apple genome to 16.9 times coverage. Unlike other Rosaceae
family plants, members of the Pyreae tribe, such as apples and pears, develop
fruit - known as the pome - from a part of their flowers called the receptacle
rather than from their ovaries.
While apples now have 17 rather than 18 chromosomes, chromosome 15 is nearly
twice the size of the others, suggesting it may represent two ancestral
chromosomes. Meanwhile, the team's comparisons between genes in wild and
domestic apple plants, including other domestic apple varieties, combined with
information in the newly sequenced genome, indicate that domesticated apple is
most closely related to a plant called M. sieversii, native to an area near
present day Kazakhstan and China.
Next, the team hopes to tease apart functional roles of genes and gene families
that seem to influence traits such as fruit production or disease resistance
and begin applying such insights - for instance, through marker-assisted
breeding efforts to help find out the best combination possible to obtain new,
high quality varieties.
