There is a lot to learn here.
I won’t comment on the process of gene transfer (or lack thereof) but here’s my experience. In 2014, I grafted Methley Plum onto 3 different varieties of Chicksaw of Hybrid trees. In 2015 they all flowered , set fruit and ripened at the same time as the original mother tree. There was no noticeable difference in the size, texture, color and taste of the fruit from the mother tree to the grafted branches. In 2016 they all continued to flower and set fruit together. However, at harvest time the grafted branched ripened about 10 day later and the fruits were about 20-30% larger, but same taste and texture. Come 2017, all started the same. At harvest the grafted branches matured about a month later than the original mother tree. This year the fruit was about 50% larger and they took on a elongated (drupe) shape and the color became blushed red/green. The fruit also became really firm. 2018 – 2019 almost everything was the same as 2017, except now they mature at least 2 months later (they hang forever, so I remove them from critters) and they now taste similar to the AU producer plum.
All three (3) varieties has shown the same characteristics regarding Methley.
Strange as it may seem, that’s my experience with grafting change.
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Very good info, thanks. I agree. Cells wounded at the union could easily pick up intracellular material from other wounded cells. So explains the graft area. Interesting subject!
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Yeah, after I posted that I tried to find other supportive studies but had no luck. I believe its safe to say that genetic transfer could happen at the graft site and the grafting could result in physical changes to what is grafted (and the fruit), but gene transfer from rootstock to fruit appears to be unlikely.
Further reading the actual article:
[…] our finding that gene transfer is restricted to the contact zone between scion and stock indicates that the changes can become heritable only via lateral shoot formation from the graft site. However, there is some reported evidence for heritable alterations induced by grafting (7) and, in light of our findings, these cases certainly warrant detailed molecular investigation.
The paper it sites as (7) is 7. Y. Ohta, P. V. Chuong,Euphytica24, 355 (1975)
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There are peer reviewed articles indicating some chemicals can transpose across graft unions and directly affect DNA in the scion. One example easily found on the net is of grafting a white tomato variety onto a rootstock that has all the genes to produce red tomatoes. The white tomato scion will produce pink fruit. Not only that, seed saved from the white tomato scion will produce plants that make pink fruit. The evidence - and it is very solid - is that some DNA changes do occur in the scion caused by rootstock influence. For some relevant reading. Lamarckism - Wikipedia Epigenetics - Wikipedia Genomic imprinting - Wikipedia
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Lots of interesting ideas in this thread. I have always wondered how some of this worked in relationship with grafts and seeds of different fruit. Now you all have me thinking about planting apple seeds and seeing what I can come up with! 
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I think there is plenty still to chew on here. We have come quite far in the new field of Epigenetics with regards to humans, yet we have barely scratched the surface of the truth. With regards to epigenetics in plants, have we even thought about scratching the surface? I also think that what we currently call “random genetic mutations” might one day seem not so random after all.
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Actually to me it appears to be going more the other way. More genes are formed randomly than we thought. We discovered the purpose of junk DNA. It is a reserve gene pool. Mostly untested randomly formed DNA sequences. Sometimes a strange gene appears and we could never explain it’s origins. Now we know it was in the junk DNA. Why only occasionally a sequence or sequences are used from that portion the chromosome are not really understood yet.
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What I was getting at is that I believe there is an element of intelligence involved. Of course we can’t prove it yet, but I don’t believe anything regarding creation is random. I think we’ll only discover that intelligence is involved increasingly more than we previously assumed.
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OK, I get it. I guess you should not rule out anything.
You know many trees will merge roots . The roots run into each then grow into each other. Sometimes this is accomplished by mycorrhizal fungi linking the trees of the same or similar species. I saw a study on peas or beans? Forget? Where they were linked by mycorrhizal fungi, and when the first plant got aphids, all three produced insect defense chemicals. as all plants in the network were alerted of the danger by the fungi connecting them. Unreal what we are finding out. A whole forest can be connected. Some mycorrhizal fungi are one organism 20 miles or more wide.One was found in my state Michigan. These large fungi produce mushrooms the size of the Stanley cup! Very rare to find. I have seen pictures of the mushrooms. They also produce a nectar that the bees drink in old growth forests.
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WHAAAT!? Bees drink mushroom nectar? New niche honey crop.
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Yes and bees who consume the nectar are resistant to colony collapse disorder. It is believed that the destruction of old growth forest and the decrease in these fungi have contributed to colony collapse disorder due to weakened immune systems. Currently studies are underway. the fungi is being propagated for use in the study.
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i have a mountain ash growing in a notch of my 40 yr. old black willow. when i 1st saw it, i thought it couldn’t possibly survive there long. now its 7ft. tall. it only collects rain there. how else is it getting nutrition? obviously its getting some as its grown 7ft. in 5 yrs. must be tapping into the b. willow.
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Very possible it could be direct or via fungi. Most trees use the same fungi. The fungi will distribute nutrition.
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I’m guessing there is some rot of the oldest wood in the willow. It can be very much like soil in there, and the living tree will keep it plenty moist even if rain never collects. There’s a crabapple growing out of a maple tree in a local park that flowers magnificently every spring.
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some leaves and debris may have collected in there before the seed spouted. black willow has deep furrowed corky bark so it should hold nutrients and water well.
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At my cottage planting is difficult. We still have 200 year old trees and I don’t care where you dig on the island it is this incredible mass of tangled roots. If a tree takes three years to become established. It will take six on the island. I’m putting two in next spring but in raised beds to try and get them to competitive size before they compete. Raised beds or mounds should be done for all trees anyway. Willow trees are great for the water’s edge as they have massive roots that hold the soil. I doubt you could rot a willow? They love water and I have seen them with wet feet for months and not die.
At my cottage the water is extremely high. One part of the island which is a small island itself, we call Anderson Island. Well Anderson island was 90% underwater spring and summer. Some people came up, and closed up and skipped the season altogether. I’m in the middle of the island and for once being an inlander has an advantage.
The water level is so high it was spilling over unto the road. It’s not from rain. As the year went on it became worse. Lot’s of brakewall work! The marine contractors made a killing.
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I’m at the bottom of a hill and on one side of me is a wetland spot that drains into a fire pond. the prior owner planted a dozen black willow over 40 yrs ago around the edge of my property. these suckers are huge and have huge root systems. i wouldn’t be surprised if some of them extended into my leach field. i removed 2 so far . would like them all gone because they are so messy. would cost me a small fortune to get rid of all of them. the one behind the house was 5ft. on the stump and was leaning right over our bedroom. cost me $800 to get rid of just that 1!
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I have had to pay and the tree was 120 feet tall. It required a crane. This guy would go up on the crane ball to cut! Plus the tree was hollow. He told me he had sex last night as it might be his last time! (He did say that!) Hollow trees are unpredictable on how they fall when cutting. He ties himself to 2 safety lines. I paid a bundle! He get’s off the crane and parks himself in the tree 80 feet up!
Slowly bringing the top cut down.
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Yes it is slightly more likely, but the amount of heritable genetic transfer across a graft union is usually very low. Graft hybridisation is poorly understood and poorly studied (as there is no money in it), but it does occur.
There are a number of peer reviewed papers on the topic, some are recent while others are from the early 1900s. I can try to find a list when I am at work next. A quick google search returns:
They usually appear to come true to type, but not always.
While investigating this a few years ago I grafted potato leaf tomato scions onto regular leaf tomato rootstock. I bagged flowers before they opened, allowed them to self pollinate, and planted 400 seeds from the potato leaf scions. From 400 seedlings 21 were regular leaf.
I grafted regular leaf tomato to potato leaf rootstock, and allowed one branch on the rootstock to fruit. Again i bagged this before the flowers opened. From 400 seedlings I had 14 regular leaf.
I also grafted potato leaf scion to potato leaf rootstock, I bagged flowers the same as above, and had the expected 0 regular leaf seedlings from 395 seedlings.
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