Gr gene

[nicollas]

Hi,

i'm not sure of understanding the Gr (green ripe) gene. Sometimes it is said that it is similar to gf but with red interior, but it seems also linked to delayed ripening. Does someone knows if including Gr gene affects maturity/flavor in a negative way ? I'm not found of breeding for supermarket carboard tomatoes.

[carolyn137]

Originally Posted by nicollas

Hi,

i'm not sure of understanding the Gr (green ripe) gene. Sometimes it is said that it is similar to gf but with red interior, but it seems also linked to delayed ripening. Does someone knows if including Gr gene affects maturity/flavor in a negative way ? I'm not found of breeding for supermarket carboard tomatoes.

I think the person you should ask about this is Mark, Frogsleap farm, who has been involved with nor and rin and other genes that affect ripening.

Personally I've not heard of a Gr gene but do know about the 5 gf genes.

Best to ask Mark about it in the thread he started here called Baffled which is in this same forum below yours.

Here's the link to help you find it but do ask him in his Baffled thread, I think that's best b/c then you can see what he's been dealing with and also his pictures.

http://tomatoville.com/showthread.php?t=38399

Carolyn

[travis]

When you're finished reading this, maybe you can summarize it in plain ol' everyday English for me:

http://www.pnas.org/content/103/20/7923.long

[Fred Hempel]

Looks like the GR protein normally acts upstream of ethylene signaling (perhaps as an inhibitor of a gene critical in the Ethylene production pathway(s) early in fruit development)

Could normally act as a natural "inhibitor" that is normally removed or interfered with during ripening, so it might be that over-expression of the protein also stops the normal removal or interference mechanism (the study says that in the mutant a protein that is overexpressed suppresses ethylene pathways AND overexpression of the same protein in an experimental transgenic plant causes the same effect)

The paper was published in 2006.. wonder if they know more about mechanism now?

[Fred Hempel]

Confusing.

This more recent paper says that the Gr mutant has a deletion in the GR gene (and not that it results in over-expression which seems to be at least assumed by the first paper).

Perhaps the deletion is in a portion of an "inhibitor" protein (GR) that is important for targeting it for breakdown during the start of ripening -- this would result in an inhibitor that can't be removed from the "promoters" that it is bound to.

In this case the mutant and the overexpression plants would work via different mechanisms. The overexpression plants might simply have so much GR, so that it can't be effectively removed (the normal removal process is swamped out).

[PhilaGardener]

Differential Control of Ethylene Responses by GREEN-RIPE and GREEN-RIPE LIKE1 Provides Evidence for Distinct Ethylene Signaling Modules in Tomato (2012)


http://www.plantphysiol.org/content/160/4/1968.full , full text available through open access.

[Fred Hempel]

Originally Posted by PhilaGardener

Differential Control of Ethylene Responses by GREEN-RIPE and GREEN-RIPE LIKE1 Provides Evidence for Distinct Ethylene Signaling Modules in Tomato (2012)


http://www.plantphysiol.org/content/160/4/1968.full , full text available through open access.

Should have know a GR-like protein would eventually show up to make things even more complicated!

[carolyn137]

Originally Posted by travis

When you're finished reading this, maybe you can summarize it in plain ol' everyday English for me:

http://www.pnas.org/content/103/20/7923.long

I skimmed the paper but when it came to Fig #4 and the clads and didn't see tomato, I said what the heck and played some music vids as I always do before I go to bed, but then got a follow up e-mail sent home with Fred's posts and saw the second one referred to tomatoes and skimmed both of those as well.

Summary?

IMO it's all about gassing unripe tomatoes with ethylene as many places do in huge chambers, you know them already as the pale pink ones that are shipped up north from FL and Mexico and wherever, that many of us know as shipped in winter tomatoes , supermarket tomatoes, with no taste but sure are pretty and some varieties are gassable and others aren't.

Carolyn, big money in gassing unripe tomatoes, so grants probably made available to do genetic research on which varieties are the most gassable or to construct same.

[Fred Hempel]

Back to your original question -- The "normal" Gr GENE (and the protein that it encodes) is a normal part of fruit ripening. It looks like it is important for preventing pre-mature ripening, which is probably not desired in most cases.

The "mutant" Gr gene discussed in the papers interferes with the normal ripening processes (because the mutant Gr doesn't work right -- it's inhibition of ripening isn't overcome at the proper time. By inhibiting ripening too strongly, the mutant form of the gene certainly affects flavor (by not allowing ripening).

Certainly Gr mutants could be used in "the industry" to slow ripening, allowing for direct application of Ethylene (and "ripening"). However it is certainly not required for "industrial" tomatoes, as you can simply pick "mature-green" tomatoes and gas them with ethylene just as easily, and perhaps even more effectively.

Originally Posted by nicollas

Hi,

i'm not sure of understanding the Gr (green ripe) gene. Sometimes it is said that it is similar to gf but with red interior, but it seems also linked to delayed ripening. Does someone knows if including Gr gene affects maturity/flavor in a negative way ? I'm not found of breeding for supermarket carboard tomatoes.

[nicollas]

Thanks, so its better staying away from it

[travis]

What are the visual signs of the phenotype, and how do they differ from rin and other ripening inhibitor genes? I mean by first visual examination, not by growing F2s to see the dominance, but in the first instance.

[Darren Abbey]

Originally Posted by travis

What are the visual signs of the phenotype, and how do they differ from rin and other ripening inhibitor genes? I mean by first visual examination, not by growing F2s to see the dominance, but in the first instance.

The heart of the tomato ripens normally, while the outside does not.