Quote:
Originally Posted by Basjoofriend
It is not possible to cross diploid with triploid. Dwarf Orinoco is triploid, also Dwarf Brazilian is triploid.
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That's not entirely true. Triploid varieties can pollinate other varieties. The fertility of the pollen is about 9 times lower, but that's still enough for pollenation.
It's even possible for triploids to serve as the female parent but the issue is there are so exceedingly few seeds (only 1 or 2 seeds per bunch of bananas, and even far lower for Cavendish, 1 per every 100 bunches).
References:
Pollen fertility in Musa: Viability in cultivars grown in Southern Australia, J. A. Fortescue, D. W. Turner, Australian Journal of Agricultural Research, January 2004
Improvement of Cavendish Banana Cultivars through Conventional Breeding, J.F. Aguilar Morán Fundación Hondureña de Investigación Agrícola (FHIA) La Lima Honduras
Quote:
Originally Posted by Gabe15
Well, you would need to do a lot more than just triploidize it, remember that being triploid has nothing to do with being parthenocarpic, a plant must first be parthenocarpic to form seedless fruit, being triploid simply is an advantage because it usually helps keep the plant sterile so seeds do not form (in addition to other advantages). This is why in order to utilize wild species for breeding, they must be bred with an edible variety that has the parthenocarpic trait (which is a chemical process independent from ploidy levels), if you just make wild species triploid, you will have sterile plants that are not able to form ripe fruit either.
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I may be mistaken but I believe simply getting a triploid banana variety is enough to make it seedless, or virtually seedless, though there might be one or two seeds in the bunch. The Cavendish variety (commonly sold in supermarkets) is even more exceedingly seedless though.
The advantage of using a seedless banana variety for pollination is there's a possibility the combined progeny will end up seedless again down in the third generation.
A substantial fraction of the triploid pollen that is viable is unreduced, meaning it still carries a full triploid set in its gamete. (It's not that the probability of escaping unreduced is inherently higher in triploids, but rather so few of the triploids that do undergo division are viable) When this combines with a normal haploid gamete, the result is a tetraploid.
3n + 1n = 4n.
When a tetraploid banana then crosses again with a normal diploid (seeded), the result is a triploid, which will be seedless.
4n --> 2n + 2n
2n --> 1n + 1n
2n + 1n = 3n