What's the difference between the Mamas and the Papas?

The choice of whether to use a particular rose as a pollen parent, seed parent or both is overwhelmingly dictated by circumstance but it does make a difference genetically.

Roses don’t have sex chromosomes. Rather, the genetic differences are due to the fact that seedlings get both their chloroplasts and mitochondria only from their Mama. Chloroplasts and mitochondria have their own DNA. This raises a broad question.

Are there traits in roses that only inherit maternally?

Two potential types of traits that come to mind, because of what the chloroplast and mitochondrial genes control, are color (carotenoids) and vigor (energy metabolism).

My work suggests that mossing is inherited far more often when Scarlet Moss is used as the female than when it is used as the male. I’ve discussed this with several people who think that may be evidence that there is cytoplasmic DNA for the moss trait.

I wouldn’t rule out epigenetics for maternal or paternal trait inheritance. It is often called imprinting and for sure it happens in early stages of development of many species.

What would be really interesting to look at is when (if) you do get mossing from Scarlet Moss pollen, does that seedling transfer the trait more often as a mother or father? If it is a general maternal effect (imprinting) then yes, the effect will come more often in seeds borne by the S.M. offspring than in it’s pollen children. If it really is a cytoplasmic trait, but somehow there is a complementary pollen-carried trait, all bets are off. Too complicated for my brain.

Breeders of field crops used to consider cytoplasm very important. Even though there are few discrete, characterized genes in either chloroplasts or mitochondria, there is a big effect of having those few genes be happy with the ones provided by the nuclear genome. And for all we know there may be controlling RNA molecules (siRNA, RNAi, microRNAs) produced in those organelles that have a big effect on the nuclear genome expression. I have not yet seen an article discussing that, one way or the other. I guess I’ll go take a look.

Hi Don,

With modern roses I wonder if there is very much variability in the DNA of the chloroplasts and mitochondria between rose varieties. It would be interesting to see a study on this. If variability is minimal, then the effect would be minimal.

With regard to vigor, in a given cross between variety “A” and variety “B”, in a large population the resulting seedlings usually have amazing variability in vigor - some very vigorous while others are incredibly weak. Whatever cytoplasmic effect there is, it would seem weak in comparison to what is transmitted in nuclear DNA by both parents.

I believe that there is little difference between mamas and papas, and always try to select crosses in the direction of greatest hip set and germination. There are exceptions to this rule, but efficiency is a high priority for me.

Jim Sproul

I would assume that the answer to this question would be highly variable and dependant.

How often does anyone get a rugosa seedling that is a TRUE hybrid that still doesn’t STRONGLY resemble rugosa? IMO it’s hard to get away from MOM’s influence to any strong degree… also, although I’m not going to try and explain it, triploids act differently as moms than dads as far as the genetic composition of the seedlings.

In my experience I found that Rugosas don

Paul is right, rugosa offsprings from wide crosses that look strongly like mom are mostly selfs or OP from another rugosa.

Rugosa seedlings can have allmost nothing looking like this species except the short petal life and often (not allways) generous spination.

I.e. rugosa x clinophylla (I got a little hundred of) is barely different from father.

Same for many synstylae.

Let my try a different tact. I started playing with lilies long before roses (8-9 yrs ago?). Singularly, I’m interested in yellow lilies.

This is one of my yellow lilies. Notice it is short, offsets easily, sparse and rather alternate foliage.



This is another yellow lily that a neighbor gave me. It’s tall, and well foliated (no offsets).



I crossed the two both ways. I’m positive (in my own mind) that these are the result of MY hybridization of one with the other. These are the nine month old seedlings (those from my lily at top and neighbors lily bottom).



You can CLEARLY see phenotypic differences starting to set in the progeny between the two seed parents. Based on these results I think it does make a difference on who gets used as a popa and moma.

I dunno, Jon. The difference seems to correlate strongly with the shape of the pots…

LOL…

I know with my gardenia cross I debated on whether to grow the two seed parents separate or together. I grew them together, I kind of wish I hadn’t now…

Hypothetically speaking, inheritance of the maternal (seed parent’s) cytoplasmic DNA would be expected to make a difference to the outcome of the cross, if there is a mutatant gene in the maternal cytoplasmic DNA which were able to phenotypically express iteslf in the progeny…The reverse cross should theoretically never show that genotype or phenotype.