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Post by raymondo on Nov 1, 2015 6:08:23 GMT -5
raymondo, got my first decent yellow snap six weeks ago. A few nice powdery mildew resistant snows fell out as well for further evaluation. Hoping there will be some more nice snaps in that group too. Haven't put much work into a lone purple snap line - one will likely come out of the red project. Saying that I did a cross just last week for a stringless purple snap line... Excellent. I trialled a stringless snap a few years back. I got very poor germination and those that did come up were weak plants. From what I read at the time, it seems that stringlessness brings a host of unwanted features along with it. I had neither the time nor the inclination to grow out enough, after having to first bulk it up, to hope that crossing over might just relieve some offspring of the unwanted alleles, so I let that one drop. Is your stringless cultivar better equipped? |
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Post by templeton on Nov 1, 2015 6:31:38 GMT -5
Sounds promising, steve1. We will have to compare notes... I've got some red snows on the way, but my purple snaps are still a bit fibrous. Got another gene to get in there. Are your reds based on Purple over yellow, or that b gene? Would love to hear your development process. t |
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Post by steve1 on Nov 1, 2015 15:37:39 GMT -5
raymondo, I had read the early string-less varieties were not vigorous and that from memory these varieties also has 'slow pollen' resulting in less than Mendelian segregation in crosses. This gene is not so-common down here. This variety had near 100% germination from what i remember, but the seed was soaked till radical emergence then potted and placed on a heat bench till proper germination. Not the real world or even close. Seems pretty good though. @t I managed two red semi-snows in the last generation, which was more than I could reasonably expect, all my red lines are purple over yellow. When you say your purple snaps are a bit fibrous - are you talking peel-able endocarp on mature pods? To me this seems to be a both dominant gene phenomenon at least so far as I can tell at the moment. Interestingly, the line of sugar snap I have is ppVV (dorsal parchment) and the Golden Sweet snow is PPvv (thin parchment in patches across the pod). You guessed it - the F2 Golden Snap project had a lot of fully parchmented peas (including snaps). Was going to attach an endocarp picture but the forum has exceeded it's space allocation! Cheers.
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Post by templeton on Nov 2, 2015 8:03:56 GMT -5
steve1, I did some microscope inspection of pod walls a couple of years ago looking for pod parchment, but couldn't really discern differences. didn't think to let the pods thicken. Tomorrow the peeling begins! Any other hints on picking p and v differences? T
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Post by steve1 on Nov 2, 2015 8:39:24 GMT -5
templeton - pod parchment happens in layers according to my reading. But some genotypes appear to really delay parchment formation. The Yakumo line I have has a peel able endocarp when mature and is basically a shelling type used as a snow. Hints: The ppVV genotype, I've noticed the dorsal ridge of the pod often has over expressed string and parchment that under a strong light shows up as a thick dark strip. I have some stained pod pictures showing this, and it confers with Rasmussons 1927 paper regarding this. The reverse PPvv genotype on the ones I have looked at is pretty subtle even stained though I believe it can be a bit variable. It's the result of the parchment being reduced very significantly by the presence of either pair of recessive genes. There is also the classical dried appearance of pods- stiff if fully parchmented and wrinkled on the seed if either or both recessive genes present. When the forum lets us I will post pictures I will give relevant examples. Hope that helps. Steve
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Post by templeton on Nov 2, 2015 16:06:12 GMT -5
steve1, thanks for the explanation - after all these years of growouts, I'm embarrassed I haven't investigated it more. I have been using empirical tests - my teeth. Gentle biting - if your teeth meet, low fibre. If they don't, at least some fibre. Joseph Lofthouse uses the pulverized pod test in dry pods - if they crush really easily in the hand, = low fibre. Then there's the curly pod characteristic in big pods, but I haven't investigated systematically. The forum is unlikely to allow direct posting of pics any time soon. You need to upload to a photo sharing site like picasa or photobucket, then paste the url into your thread post, have a look at the sticky threads on the forum. It's a bit of a drag, but does limit any snap-happy tendencies I might otherwise have. Wish i had a day in the garden with the sun shining, but have to work today, no holiday in the bush.
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Post by steve1 on Nov 2, 2015 19:04:00 GMT -5
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Post by steve1 on Nov 2, 2015 20:33:12 GMT -5
Hi Templeton, Dry pods tell about the presence/absence of the recessive parchment traits. However the change is present with just one of the recessive parchment genes (pp or vv) and I don't think you can say more than that. Rasmusson 1927 'Genetically changed linkage values in Pisum' and Myers, Baggett and Lamborn. Plant Breeding Reviews Vol.21 Snap pea both have illustrations of this. These pics are from the parent (Sugar Snap) and one of my fully parchmented snap plants. dl.dropboxusercontent.com/u/94877168/SugarSnapdry.jpgdl.dropboxusercontent.com/u/94877168/SnapFullpmentdry.jpgHere is the peeled parchment in a red line (PPVV) note it's not a very mature pod either. dl.dropboxusercontent.com/u/94877168/redcomp.jpgMy method testing (with a mature non dry pod) is to halve the pod along the seams, then snap the pod in half outside to inside. If it peels its very likely PPVV. I only had the one recessive parchment gene in this cross (from staining the parents), so I hoped when I saw the pod adhering to the seed I was dealing with a (PPvv) line. You can see the semi-dried pods are shriveled around the peas indicating the presence of the single recessive genotype. dl.dropboxusercontent.com/u/94877168/RPL3drying.jpgI don't think you can classify this whilst the pod is growing however, you need mature dry pods. My line of Yakumo I have is a case in point. Hope that has added something and probably should be in another thread. I will try the grind to powder method when I have more dry pods of a line with both recessive parchment genes. Cheers |
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Post by philagardener on Nov 3, 2015 6:34:35 GMT -5
Great images and information, steve1 ! Thank you for sharing! |
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Post by templeton on Nov 3, 2015 17:29:46 GMT -5
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Post by raymondo on Nov 3, 2015 19:14:04 GMT -5
Are you going to take out breeder's rights on your purple pea in the European Union? |
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Post by steve1 on Nov 3, 2015 20:06:54 GMT -5
templeton, I've been using Phloroglucinol/ethanol/conc HCL (weisner test for lignin) on my fresh pods so far. No good with anthocyanins though. Phenols mess up the stain. Working on that at the moment. Have also been looking at the pods under light, my thought is you can see the VV genotype as shading under light and in stained transverse section. Haven't done all the data analysis yet to see if it makes sense. Like the protocols, and will try the staining on dry pods in the next few days and report back. The fresh pods show presence of significant parchment well enough, but making a call on PPvv genotypes with green pods is much harder. I have several price hedley papers on the gp gene, but tended to use a modified protocol by Drew 'cloning characteristics of genes determining pod morphology in pea' for staining fresh. It's another ethesis free online @ Durham university. I'll link some pictures from staining if it's useful. Cheers
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Post by philagardener on Nov 3, 2015 21:02:07 GMT -5
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Post by steve1 on Nov 3, 2015 22:10:24 GMT -5
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Post by templeton on Nov 3, 2015 23:21:02 GMT -5
Found the durham phd this morning, was about to post the link myself  |
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