Seedlessness in grapes is not due to triploidy although that seems to
be a common misconception. Most seedless grape cultivars are not even
parthenocarpic, as are most other species or cultivars that produce
seedless fruit. Parthenocarpic species or cultivars produce fruit
without fertilization so the fruit are truly seedless. 'Black
Corinth'is considered a parthenocarpic grape.

Most seedless grapes are stenospermocarpic, which means the seeds
start to develop after normal pollination and fertilization but abort
before maturity. The remains of the aborted seed(s), called seed
traces, can be seen in the "seedless" fruit.

Grape breeders now use tissue culture to prevent the tiny embryos from
aborting. This technique is called embryo rescue. It allows two
seedless grapes to be crossed and produce viable offspring. Embryo
rescue had been a major reason why there are so many new seedless
grape cultivars.

References

Table Grape Berry Growth and Development: A Review
http://cetulare.ucdavis.edu/pub/Grape0302.PDF

SEEDLESS GRAPE: Use of biotechnology to find new seedless cultivars
http://www.biotecnologia.com.br/bio/10_gi.htm

Trio of New Seedless Grapes on the Way to Consumers
http://www.ars.usda.gov/is/pr/1999/990618.htm



ose (Sean Houtman) wrote in message ...



More often when plants have triploids, the result is no seeds in the fruit.
Examples are seedless grapes and seedless bananas.

Sean