MadSci Network: Botany

Re: how are seedless grapes produced?

Date: Sat May 19 16:15:08 2001
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 990273282.Bt

Seedless grapes are seedless because the seed aborts during development, termed 
stenspermocarpy. You can see the remnant of the aborted seed(s) in the grape. 
Grape breeders have found a way to remove the developing embryo when it is very 
small to prevent it from aborting, termed embryo rescue. They can then raise 
seedless grapes from the rescued embryos to use in breeding new types of 
seedless grapes. For vineyards, seedless grapes are grafted.

Because the seed aborts, seedless grapes do not enlarge as much as seeded 
grapes. The seed produces plant hormones that cause fruit enlargement. To 
increase their size, seedless grapes are sprayed with the plant hormone, 
gibberellic acid, which allows them to reach normal size.

Fruits become seedless, termed parthenocarpy, in a variety of ways. Bananas are 
seedless because they are triploid. Triploid plants cannot undergo meiosis, a 
process necessary for sexual seed formation. Pineapples are seedless because 
they are self-infertile, meaning they cannot set seed when they self pollinate. 
To assure that pineapples are seedless, only one variety is grown, so only self 
pollination is possible. Persimmon trees are either male or female. If no male 
trees are nearby to provide pollination, then fruits are seedless. Naval 
oranges all come from a tree that arose as a mutation. Seedless watermelons are 
also triploid but are grown from seeds that occur when a diploid and tetraploid 
are crossed.

Seedless fruit are very desirable because many fruits have hard or hard-to-
digest seeds. Genetic engineers have come up with several ways to incorporate 
genes into plants to make the fruit seedless. Therefore, it may soon be 
possible to have seedless fruit of almost any species.


COMING SOON: Wider Selection of (Genetically Engineered) Seedless Fruit 

Seedless Summer Fruits

Naval Oranges

Grape Embryo Rescue

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