When an F1 plant undergoes meiosis, the gamete types it produces are determined by its parental genotypes. If a parent is heterozygous for a particular trait, then one of each gamete type will be produced when it undergoes meiosis. The proportion of those two gamete types will depend on how dominant or recessive the traits are in that specific genetic combination. Let’s look at some examples to see this in action!
If an F0 plant is heterozygous for color, and one of its parents produces red gametes while the other parent has green gametes, then when that F0 plant undergoes meiosis it will produce two types of gametes: some with a genotype matching the red parent’s allele (Rr) and some with a genotype matching the other parent’s allele (rr). The proportion of these two types of gamete will depend on how dominant or recessive those genes are.
If both plants in this example were homozygous for their colors, meaning they had R alleles from both parents as well as g alleles from both parents at each locus, then there would be four types of gametes produced: RR, Rr, rR and rr. The probability that the F0 plant produces a red allele (RR) is 25% while the chance it will produce green alleles (rr) is also 25%.
If one parent had two copies of its dominant color gene (RR), then when this F0 plant undergoes meiosis there would be three colors possible in each gamete type: heterozygous for both parents’ recessive genes or homozygous for one parent’s dominant gene. So if we have an example with red and yellow plants like before, when they mate to create an F0 generation those offspring might end up producing either RGBG – all four combinations are equally likely – or RYG, YRR and yyr.
If the other parent had two copies of its recessive color gene (rr), then when this F0 plant undergoes meiosis there would be no red alleles in any gamete type: heterozygous for both parents’ dominant genes or homozygous for one parent’s recessive gene. So if we have an example with red plants and yellow plants like before, when they mate to create an F0 generation those offspring might end up producing RGBR or BRY all four combinations equally likely but not RBG.
The more green alleles a seed has from either of its parents, the less chance it will carry any copy of that allele as a dominant gene.
An F0 plant with green pollen and red flowers might produce gametes that are either GGR or GRG, but not GGY because the original homozygous recessive genotype is GgRr which will give us a heterozygous (GG) when it goes through meiosis in an f0 plant.
If we have an example with yellow plants for both parents – like before – then when this F0 generation of seedlings undergoes meiosis there would be no copies of those dominant genes in any gamete type: heterozygous for both parents’ dominant alleles or homozygous for one parent’s recessive allele. So if we just had these same two colors from have gametes that are GGR then when they go through meiosis in an F0 plant, we would get a 50% chance of getting GG and 50% of GRG.
But if both parents have dominant alleles for the same trait like green pollen or red flowers, this is where it gets interesting because we now have two competing genes – one from each parent – which could lead to either RGG or grrR depending on what type of gamete is produced (remember that recessive traits will show up as homozygous).
If you want more information about how many copies there might be of these alleles in offspring with different combinations, check out our article “What Gamete Types Will an F0 Plant Produce, and in What Proportions?”
What Gamete Types Will an F0 Plant Produce, and in What Proportions?
when an f0 plant undergoes meiosis
what gamete types will it produce
and in what proportions?
*you might want to consider adding a question mark after “proportion” since this is technically not the correct term. A better word would be probability of getting that particular trait. But I know there are some biology people reading over this post so you can decide whether or not you should edit the text.*
If we just had these same two colors from have gametes that are GGR then when they go through meiosis, they will produce gametes that are either GGR or RGG.