Baffled.
 

Last summer I picked up a tomato on the side of the road in Davis, CA (Old Davis Rd). It was one of many hundred that had fallen off a truck hauling processing tomatoes from field to processor. The fruit was firm, crimson in color, and with a rich tomato taste. I extracted seed and planted three F2 progeny this spring. Two plants gave typical paste type tomatoes on a determinate vine, one (and the one I crossed to) had larger fruit that appeared to never ripen. I finally picked the two crosses when they showed a very subtle blushing, and waited for them to turn color indoors. This morning, three weeks later, no additional fruit coloration - I sliced open fruit from both crosses.

Fruit is hard a rock, yellow color, faint hint of rose blush. To my surprise the locules were filled with a scarlet gel and mature seeds. I know that some of the newest processing hybrids have a delayed harvest feature - allowing a long harvest window for mature fruit. I'm wondering if this is like "rin", never ripens in the homozygous state, but enhanced shelf life of fully ripe when heterozygous. I'm confident I'll figure this out, but for now I'm baffled. Any ideas?

[URL="http://www.funpecrp.com.br/gmr/year2013/vol12-1/pdf/gmr2346.pdf"]http://www.funpecrp.com.br/gmr/year2013/vol12-1/pdf/gmr2346.pdf[/URL]

Looks like "alc"?

I just confirmed that the mutant allele alc confers Extended Field Storage (EFS) in many modern hybrids grown for tomato processing. I am guessing I happened to find a alc/alc ogc/ogc segregant in the F2.

[QUOTE=frogsleap farm;503393]I just confirmed that the mutant allele alc confers Extended Field Storage (EFS) in many modern hybrids grown for tomato processing. I am guessing I happened to find a alc/alc ogc/ogc segregant in the F2.[/QUOTE]

Ilex from Spain had mentioned the alc gene here quite recently.

So it's either what you think it is or someone else threw some Dourne d Hiver fruits, the rin mutant I sent you, on that truck, but no, the exterior you showed is not my precious Dourne de Hivre.;):lol:

Carolyn

Very interesting!

Obviously.

I have a lot of questions about the genetics of 'firmness' and texture and slow ripening myself, after this past season growing F2's of a cross with Zolotoe Serdtse.

The F1 crosses were as firm and slow ripening as the mother ZS.
The F2's varied a little, but every one of them had some degree of the slow ripening and firm texture.

Frogsleap, that's a very interesting paper you posted. I half understand what is being said about skewed distributions, but I am still confused about nor, rin and alc all appearing to be recessive? While the paper also says a large number of dominant genes are involved. :?!?: And for fruit firmness they identified four QTL's.. I don't understand how that corresponds to the three 'mutants' alc nor rin. :oops:

[QUOTE=frogsleap farm;503393]I just confirmed that the mutant allele alc confers Extended Field Storage (EFS) in many modern hybrids grown for tomato processing. I am guessing I happened to find a alc/alc ogc/ogc segregant in the F2.[/QUOTE]

I just went out to get OP seed - I think it may be something special.

[QUOTE=frogsleap farm;503426]I just went out to get OP seed - I think it may be something special.[/QUOTE]

That's amazing! Is the flesh also ripe, I mean, a ripe texture?

It looks pretty stingy for seed production.

Mike, do you save seeds directly in the baggie?

Yes, I just squeeze the innards into a baggie, seal it up for 2-3 days and then rinse and dry. Although the inside of the fruit has pigmentation, it is still very firm and there is no flavor.

Do you have a way to measure Brix?

[QUOTE=travis;503617]Do you have a way to measure Brix?[/QUOTE]

I have a refractometer that I use occasionally. I didn't test this fruit, there is zero sweetness. I'm working a lot with rin also, and in contrast the rin/rin lines can have some noticeable sweetness, but no carotenoid pigmentation.

I haven't had time to dig into alc much yet, but I'm interested in knowing more about the various approaches for delayed ripening-extended shelf-life. I'll probably post something on my blog when I get this figured out. I'm a plant biochem geek and fascinated by regulation of complex pathways by transcription factors (e.g. Rin) and other regulatory sequences.

[QUOTE=frogsleap farm;504001]I have a refractometer that I use occasionally. I didn't test this fruit, there is zero sweetness. I'm working a lot with rin also, and in contrast the rin/rin lines can have some noticeable sweetness, but no carotenoid pigmentation.

I haven't had time to dig into alc much yet, but I'm interested in knowing more about the various approaches for delayed ripening-extended shelf-life. I'll probably post something on my blog when I get this figured out. I'm a plant biochem geek and fascinated by regulation of complex pathways by transcription factors (e.g. Rin) and other regulatory sequences.[/QUOTE]

Plant biochem geek? Why not.;)

Mark, I know that you are interested in long storage and/or or delayed ripening mechanisms with rin, nor and now alc, but I was wondering if you know any work that's been done with tomatoes where control of transcription was related to the degree and placement of methylation of the DNA.

I ask only b'c I did a paper that showed that Bacteriophge T1 could induce such methylation of the bacterial host.

I haven't reviewed the whole area of DNA methylation as a transcription controller in a long time and wonder if it's been reported in other systems, such as tomatoes.

Carolyn

Methylation of gene promoters or coding sequences is a common method of gene silencing and can be under genetic and/or epigenetic control. This is one of several mechanisms in how plants/animal/microbes manage gene expression. As you know, this is an exciting and emerging field in biology/genetics. The roles of micro-RNAs and transcription factors in regulating individual genes and/or whole metabolic pathways is now probably better understood in humans than in plants - but the principles are very similar. Rin is a classic transcription factor that regulates, directly or indirectly, several different processes in tomato fruit - together controlling the fruit ripening process. Methylation/silencing of specific genes may be involved - but not sure. The recessive loss-of-function mutant "rin" results in a non-ripening phenotype, as does alc/alc, but as noted in the photos above there are other phenotypic traits that are quite different between these two mutants - thus my interest.