Tomatoville® Gardening Forums - View Single Post - A connection between F2 fruit size & seed locules in F1 fruit?

bower · September 3, 2017

hi dfollett, just saw this thread.

We had some discussion about the locule genes, lc and fas, in the Karma project thread earlier this year. It is pretty mystifying to me, especially when you throw other shape and size genes into the mix, so don't count on me for an authoritative answer...

still blundering my way through it. Iirc I found some information during the Karma discussion that was contrary to what i thought or concluded before. This is what I'm thinking now:
- cherry or wild type fruit can have 2-3 locules, not only two. I have seen 3 in a longer fruit with the Sun gene involved.
- 3-4 locules (or is it 3-5?) indicate the lc locule number gene is present. I believe it is incomplete dominant, so it does show up in F1 crosses involving a cherry.
- I am not sure how fas/- without lc would affect F1 locule number but iirc the diagram, 6 locules would be fas/fas without lc.
- None of the diagrams showed fas/- lc/- heterozygous conditions so... darkness in that corner.

- personally, if I see more locules I do save them separately and pursue that as an indicator of the larger fruit. But in my case, I have seen these in multiparent crosses ie unstable varieties crossed. I don't think I've seen these different locule numbers in a cross of two stable vars.

Some reasoning/ "thought experiment" :
- fas plus lc together make the big beefs ( plus numerous fruit size qtls). So it stands to reason that the stable beefs in your F1 crosses had both fas/fas and lc/lc
This means that all your F1's would have fas/- and lc/- present. And if both parents are completely stable, all of the F1s must be genetically identical.
If so, then the expression of more locules must be purely environmental...

What are the other possibilities?
Is it possible that one or both parents were not completely homozygous?
Could there be other genes that affect the expression of locule number from fas and lc?
Given that these possibilities do exist, it is worthwhile IMO to compare the progeny of the F1 with more locules to those without.
If I were looking for larger fruit, I would always save seed from the more loculed plant where I saw the genes expressed most often, just to hedge bets on the uncertainties/unknowns.

September 3, 2017	#7
bower Tomatovillian™ Join Date: Feb 2012 Location: Newfoundland, Canada Posts: 6,793	hi dfollett, just saw this thread. We had some discussion about the locule genes, lc and fas, in the Karma project thread earlier this year. It is pretty mystifying to me, especially when you throw other shape and size genes into the mix, so don't count on me for an authoritative answer... still blundering my way through it. Iirc I found some information during the Karma discussion that was contrary to what i thought or concluded before. This is what I'm thinking now: - cherry or wild type fruit can have 2-3 locules, not only two. I have seen 3 in a longer fruit with the Sun gene involved. - 3-4 locules (or is it 3-5?) indicate the lc locule number gene is present. I believe it is incomplete dominant, so it does show up in F1 crosses involving a cherry. - I am not sure how fas/- without lc would affect F1 locule number but iirc the diagram, 6 locules would be fas/fas without lc. - None of the diagrams showed fas/- lc/- heterozygous conditions so... darkness in that corner. - personally, if I see more locules I do save them separately and pursue that as an indicator of the larger fruit. But in my case, I have seen these in multiparent crosses ie unstable varieties crossed. I don't think I've seen these different locule numbers in a cross of two stable vars. Some reasoning/ "thought experiment" : - fas plus lc together make the big beefs ( plus numerous fruit size qtls). So it stands to reason that the stable beefs in your F1 crosses had both fas/fas and lc/lc This means that all your F1's would have fas/- and lc/- present. And if both parents are completely stable, all of the F1s must be genetically identical. If so, then the expression of more locules must be purely environmental... What are the other possibilities? Is it possible that one or both parents were not completely homozygous? Could there be other genes that affect the expression of locule number from fas and lc? Given that these possibilities do exist, it is worthwhile IMO to compare the progeny of the F1 with more locules to those without. If I were looking for larger fruit, I would always save seed from the more loculed plant where I saw the genes expressed most often, just to hedge bets on the uncertainties/unknowns.