Little?a little
Twins can result from sexual reproduction and asexual processes. Sexually produced twins (identical twins) are zygotic embryos that result from sexual reproduction whereby two gametes (1/2 of the total genetic info sex cells: sperm/egg) undergo fertilization to create a wholly new genotype/individual and split. Embryos resulting from apomixis are produced asexually when a non-egg cell produces an embryo which encompasses a clone of the mother’s complete genotype.
A common case of zygotic twin embryos would be cleavage polyembryony (identical twins). This is when a fertilized egg cell which carries a new complete genotype splits (cleaves) into multiple fully complete embryos. Since the multiple embryos split from the same sexually produced embryo, they have the identical genotype and yield identical twins. The twins are identical to each other but are different from the parents since the parents still only contributed half of the new genetic material that comprise the offspring.
The other type of polyembryony is the result of apomixis. This method of reproduction does not involve meiosis or fertilization. This phenomenon is common in citrus plants (and mangos) and is the focus of the paper you linked. There are a few ways Apomixis can take place and they each have a different term depending on the cell and pathway of development, but the general concept of apomixis is that you have embryos produced by non-egg cells.
An embryo that results from meiosis and fertilization is said to be the result of sexual reproduction yielding a new individual (genotype), while embryos produced by apomixis does not result from sexual reproduction (no meiosis/fertilization) and yields a clone of the mother’s genotype.
The paper you linked was describing the citrus plant that express apomixis in some genotypes. The experiment was able to pinpoint the citrus plants with this genetic expression through lab techniques because the coding for this trait involves an easy to find location of just a single nucleotide substitution. The results showed that there was a link between polyembryony and the presence of msg-2, suggesting that this compound is integral to the expression of the apomixis trait.
For your specific case of twins, I would be curious to find out if the twins are sexually derived or apomictic. I would try to separate the different seedlings and grow them out to see if they are identical twins to their siblings, or clones of the mother. The fact that apomixis results from asexual processes implies that any attempt to breed for it would necessitate the female which initially expresses this trait. If it can only spawn from a carrier female and only produce genetic copies, thus only females, then I wouldn’t expect it to be a trait that a male could influence.
There seems to be a correlation between higher levels of vitamin C and the incidence of twins, so you might be able to tinker with this concept and see if anything comes from it.
Link between vitamin C and twin seedlings can increase seed production in crops.
Possible, but difficult to say for sure without comparing the twins to siblings and mother.
Yes. Just as a rooted cutting originally taken from the mother's tissue results in a clone, so too does the mother's cells generating an embryo result in a clone as there is never any deconstruction of her original DNA (meiosis) or introduction of outside genetic material (fertilization) in the development from apomixis.
One of the defining characteristics of apomictic polyembryony is that there is no fertilization (influx of genetic material to pollinate) in the production of additional asexual embryos. Here is an illustration of the normal sexual development of monoembryonic seeds vs. the development of polyembryonic seeds.
In the top line, we have an embryo sac with 7 cells (3 antipodals, 1 central cell, 2 synergids, 1 egg cell in orange). The egg cell (orange) will be the recipient of the pollen and go on to form the usual single embryo embodying a mix of the mother/fathers' genes.
In the bottom line, everything proceeds as before with the exception of new embryos produced from the nucellus (maternal tissue encasing the embryo). You can see these 2 new embryos (nucellar embryos) developing in red. The result is 3 total embryos in the seed. One of these being the result of sexual reproduction and having a new genotype thanks to mixing of mother/father genes. The other two are copies of the mother's genotype (like new clones produced from cuttings) since they generated from her cells without undergoing meiosis (a deconstruction of mother's DNA) or fertilization (introduction of new genetic material).
Here is a good video describing types of apomixis:
HhhhmmHow much vitamin C does bunny get?