Welcome, Guest. Please login or register. Author Topic: Theory: percentage of nucellar seeds vary depending on the pollinator Read times. SoCal2warm Hero Member Posts: zone 10 and zone 8a. I have theory. I don't have any evidence for it, but let me share the reasoning for it. Among different citrus varieties there are some which produce a higher percentage of nucellar seeds than others. Some citrus species produce entirely zygotic seed, while other varieties produce almost entirely nucellar seed, and there are several varieties with percentages in between.
If the seed is nucellar, it will be a genetic clone of its parent. Not really a good thing if you're trying to hybridize new citrus varieties, but a good thing for those growing rootstock from seed, where uniformity is important.
The reason, it is believed, some citrus varieties form nucellar seed is that the sexual gamete cells inside the seed are not vigorous enough and can't compete with the nucellar cells. The original origin citrus species are, almost entirely without exception, all zygotic. But when different citrus species are hybridized the percentages of nucellar seed shoot up. This could be because the hybridization between different species which are not entirely compatible results in a weaker gamete megagametophyte , and so the nucellar lining takes over.
My theory is that if a hybrid citrus flower is pollinated with pollen from one of the original two species from which the hybrid originated from, the percentage of nucellar seed is likely to be lower. This would be because, the genetic composition of the megagametophyte would be less heterogenous, and thus presumably have more vigor.
So, for example, if Yuzu were pollinated by C. If this theory is true, this may confer some advantage to hybridizing new citrus varieties, since normally trying to hybridize a variety that is highly nucellar and using it as the female parent presents some pragmatic challenges. Manners once wrote that the reason that zygotic gametes loose out against nucellar is that the zygotic gametes began growing later than the nucellar.
