Hi- I’ve been spending some time trying to understand the heritability of various traits in roses. Something I have come across here and there is that when you make a cross, the seedling will inherit, say, its habit and vigour from the seed parent and colour and petal count of the pollen parent. Is there any scientific basis for this? Do plants have “sex-linked” traits? How is this possible in monoecious plants? What would be the mechanism to ensure that a particular trait is passed on in pollen only, say?
I have been searching online for any answers and haven’t found much- if you know of any resources- papers, journals, sites, etc, I’d be happy to do more studying. I’m finding I’m a bit lacking in plant genetics and would appreciate any direction.
Thanks. Enjoying reading everyone’s posts. Hope your summer is going well.
I think there are some earlier threads about this but I don’t recall their names.
There is a little bit of maternal inheritance, with some genes found in mitochondria and plastids (chloroplasts, chromoplasts etc) but most genes are in the nucleus.
There is something called imprinting in which genes in the male gamete or female gamete get modifications made to their DNA, such as methylation. So some genes may be turned on and others turned off in the newly formed embryo. Also there is some messenger RNA in the egg that gets used for the first few days of development. This is much better studied and understood in animals than in plants.
During those first days, it may be that some other genes are turned on or off depending on whether they come from one or the other parent. I don’t there is any evidence for this in roses but in some plants certainly there are some unusual things going on, particularly when little pieces of RNA called small interfering RNA, and its various relatives get involved. David Baulcombe in England has done a lot with this.
If you read the wiki article on Sir David, you’ll notice that he shared several awards with the later Nobel Prize winners for work on these little RNA bits. But they worked on animals, while he did it first in plants. That’s the way the world works.
I don’t think that quantitative genetic studies show much evidence that one whole class of traits come from either male or female parent. Of course it is true that we detect some traits more strongly expressed and looking like one parent or the other than would be expected from simple blending inheritance. That is called linkage disequilibrium. Sometimes a whole batch of genes on different chromosomes have to cooperate to make a successful plant. If one parent doesn’t have gene products that will be compatible with those of the other, something’s got to give. The seedlings that survive have the whole batch from one parent or the other. That is what makes crosses to species so hard. And may be why blackspot susceptibility seems to be linked to yellow color in modern roses.