Partial/Incomplete Cross?

[EBHarvey]

I got an interesting result when testing a black pear X flamme cross - about 1/3 of the seedlings are regular leaf as expected from a successful cross, but the rest are potato-leafed as if the black pear selfed. How is this possible? I was under the impression that, like a sperm fertilizing and egg, only one set of genetic material can get in and after it does, the door closes, so to speak.

Am I wrong? - if pollen from multiple donors gets on the same stigma can the resulting fruit's seeds produce something other than the homogeneous offspring typical of F1 hybrids?

[delltraveller]

I believe each seed is individually fertilized, so, yes, you can get different 'dads'. If you didn't remove the male parts from the 'mom' flower or were late doing so or didn't bag the blossom after doing your cross, you could get the black pear x black pear result.

[maf]

Yep, one grain of pollen = one seed.

[Worth1]

The same goes for mammals that have litters.

Worth

[EBHarvey]

Thanks for the replies, but this explanation kind of opens up a whole other can of worms....

Surely all the receptors don't need to be pollinated in order for a fruit to be produced, so if each grain of pollen effectively becomes a seed, what about the pollen receptors that don't receive any pollen? The fruit still produces a set number of seeds according to its type, no? So those seeds aren't sterile, right? ...and they're not clones of the parent plant, so........?

[Redbaron]

Originally Posted by EBHarvey

Thanks for the replies, but this explanation kind of opens up a whole other can of worms....

Surely all the receptors don't need to be pollinated in order for a fruit to be produced, so if each grain of pollen effectively becomes a seed, what about the pollen receptors that don't receive any pollen? The fruit still produces a set number of seeds according to its type, no?

[EBHarvey]

I don't get it, what does blue-faced guy shaking his head mean?

[maf]

I think the blue-faced guy means "no".

Only fertilized ova develop into seeds, and the number of seeds will vary according to the effectiveness of the pollination.

[carolyn137]

Originally Posted by EBHarvey

I don't get it, what does blue-faced guy shaking his head mean?

I'm not sure, but try this link:

http://www.kdcomm.net/~tomato/Tomato/xingtom.html

The tomato ovary has ovules in it. As was said above, one pollen grain fertilizes one ovule and becomes one seed. Any ovules not fertilized can self pollenize or be cross pollinated.

Completely normal fruit development is dependent on almost all ovules being fertilized, whether via self or crossed. Partial fertilization often leads to fruits that don't develop normally and have a lessened number of seeds.

Also look at the links at the bottom of the page that I linked to above and if you want to know more, here's the link to the whole website, which is outstanding.

http://www.kdcomm.net/~tomato/index.html

Carolyn

[EBHarvey]

Originally Posted by carolyn137

Completely normal fruit development is dependent on almost all ovules being fertilized...

Thanks Carolyn, that was what I was hung-up on.

Usually when one sees a reproductive strategy based on very large numbers and small odds (fungal spores, billions of sperm vying for an egg, etc.), it only takes one "success" for reproduction to occur, so the idea that most if not all of the ovules need to be fertilized seemed odd and out of place to me. I had assumed that a single pollen grain would do the trick.

Knowing that this is not the case sheds some light on some of my other nagging mysteries too, so thanks again.

[Redbaron]

Originally Posted by EBHarvey

I don't get it, what does blue-faced guy shaking his head mean?

It means no. Your original comment was wrong. You don't have to pollinate every ovule to produce a fruit in a tomato. Generally there is a "critical mass" reached when enough, as a %, are pollinated to make a fruit set. Any not pollinated by then will simply be absorbed generally. This sometimes can cause a misshapen fruit. In rare cases i have seen tomatoes with no seeds at all. Not sure why this happens, but i had several multifloras do that this year from time to time. The tomatoes were always tiny though.

I have gotten slapped down many times in this forum for making statements that might be older "antique" knowlege or even just plain wrong. So take this with a grain of salt.

My guess is that your seeds were "contaminated" by stray pollen. One good thing about recessive traits though. It does help you quickly identify the good from the contaminated in certain cases. The other possibility is that your flamme was not true. It could have been carrying a recessive. That would produce about 50/50 RL/PL if I remember correctly. To figure that out you would need to check for other traits.

[EBHarvey]

Ahhh...I see. Thanks for the clarification.

"Stray pollen" is a kind way of putting it - in reality it was haste and sloppiness. My cross-pollinating was done during my 1 hour lunch breaks twice a week which gave me all of about 5 minutes in the garden after travel time from my office. After about 100 failed attempts I started mixing all the donor pollen, emasculating every flower I saw with pollen-covered fingers, and just altogether rushing the process with no regard for what was pollinating what except for the PL/RL consideration. After months of meticulous planning, everything was falling apart and I just wanted to have some crosses to play with, grow out, and begin to understand the interplay of genetics through. Quite a few bore fruit in the end and I have a dozen or so seed packets labelled "Elbe X ?" "Sudduth X ?" and such, so everything is going to be a surprise, which is fine because I have no serious goals associated with any of this.

As always, thanks everyone for the input and attention.

[carolyn137]

My cross-pollinating was done during my 1 hour lunch breaks twice a week which gave me all of about 5 minutes in the garden after travel time from my office. After about 100 failed

*****

When one speaks of cross pollination it usually means that pollen from another variety, usually unknown, can fertilize unfertilized ovules in the tomato ovary and it's accidental.

Yes, you were doing so called "cross pollinating" when doing directed crosses with both parents being known to you and not accidental, so that's why cross pollination to almost all means the accidental pollination done by an unknown pollen donor.

Hope that helps.

Carolyn

[Heritage]

Originally Posted by EBHarvey

regard for what was pollinating what except for the PL/RL consideration

Harvey, maybe you know, if you do crosses using your method, is important to pollinate PL plants with only RL pollen. That way, when you grow out the F1's you will know definitely which seedlings were results of successful crosses and it will be easy to cull the selfs.

Steve

[EBHarvey]

Yes, I absolutely did that - what I meant by the PL/RL consideration.

And that's what prompted this thread - getting a mix of PL and RL seedlings out of the same fruit.