Heirloom Trees?

[shaneatwell]

This question has been bugging me for a year.

Heirloom plants are ones that when self-crossed produce progeny that are identical to the parents. They are developed by self-crossing and selecting for many generations (usually seven or more) until all the genetics are homozygous, i.e. 'fixed'. That is, genes on the two copies of every chromosome are the same (as opposed to having heterozygous dominant + recessive pairs). Thus all the self-crosses are the same as the parent because there's no diversity of genes. Heirloom plants are used by gardeners because they can replant seeds every year instead of buying new ones.

Is this ever done with fruit trees? There's not really the need and by the time you did it, your variety would probably be passe, but still. Anyone know? When I google for heirloom fruit trees all I get are varieties that have been grafted for decades, not at all the same meaning as for e.g. tomatoes.

[nullzero]

This question has been bugging me for a year.

Heirloom plants are ones that when self-crossed produce progeny that are identical to the parents. They are developed by self-crossing and selecting for many generations (usually seven or more) until all the genetics are homozygous, i.e. 'fixed'. That is, genes on the two copies of every chromosome are the same (as opposed to having heterozygous dominant + recessive pairs). Thus all the self-crosses are the same as the parent because there's no diversity of genes. Heirloom plants are used by gardeners because they can replant seeds every year instead of buying new ones.

Is this ever done with fruit trees? There's not really the need and by the time you did it, your variety would probably be passe, but still. Anyone know? When I google for heirloom fruit trees all I get are varieties that have been grafted for decades, not at all the same meaning as for e.g. tomatoes.

This would be useful for impossible to graft or airlayer plants like the Butia sp. However, since the Butia sp. takes years to fruit... the breeding effort to stabilize would take 40 years or so. Hybrid offspring from 2 good selections would work pretty well in this case. Fast to fruit from seed plants like Passiflora sp. would have more potential.

I wanted to breed some Cereus sp. and make some selections. With the Cereus sp. its a lot easier since I can grow out lots of crosses to fruiting stage then make a good selections and propagate with cuttings.

[fyliu]

In citrus at least this type of plants is labeled nucellar.
In polyembryonic mango seeds most of the seedlings would be clones of the mother plant. But clones don't offer the disease resistance of a wider gene pool.

[Bush2Beach]

As citrus goes as far as I know Lime seeds are the only true to type like their parent trees. I usually plant out rare lime seeds I come across.

[fruitlovers]

This question has been bugging me for a year.

Heirloom plants are ones that when self-crossed produce progeny that are identical to the parents. They are developed by self-crossing and selecting for many generations (usually seven or more) until all the genetics are homozygous, i.e. 'fixed'. That is, genes on the two copies of every chromosome are the same (as opposed to having heterozygous dominant + recessive pairs). Thus all the self-crosses are the same as the parent because there's no diversity of genes. Heirloom plants are used by gardeners because they can replant seeds every year instead of buying new ones.

Is this ever done with fruit trees? There's not really the need and by the time you did it, your variety would probably be passe, but still. Anyone know? When I google for heirloom fruit trees all I get are varieties that have been grafted for decades, not at all the same meaning as for e.g. tomatoes.

I think that's a bit of a complex question. Let me start by making a few short points. First it's not true that all heirloom vegetables are all fixed. I remember having grown some that were not stable and so produced different looking fruits. With vegetables usually you have either annual or bi-annual plants. I think it's much easier to stabilize them then it is with perennial plants, such as fruit trees. Also there is the important consideration of whether a plant is self pollinating or cross pollinating, in terms of how easy it is to stabilize the traits. Many vegetables are self pollinating, but not all. So i think the self pollinating ones would be easier to stabilize in just a few generations. Many fruit trees depend on cross pollination so will have more variation and not be so easy to stabilize. Some fruits that are produced asexually are very easy to stabilize, like bananas. Maybe i haven't answered your question very well, as i'm not a geneticist, but i think it's a starting point.

[Radoslav]

In citrus at least this type of plants is labeled nucellar.
In polyembryonic mango seeds most of the seedlings would be clones of the mother plant. But clones don't offer the disease resistance of a wider gene pool.

Most of citrus varieties (there are only very few exceptions, like for example citrus grandis - pomelo) can produce  nucellar seedlings, which are as you said in fact clones of the mother plant.

and by the way:  we recognize phenotype and genotype! . So, I do not believe that seedling from heirloom tree is necessary identical (clone)  to its grandparent, because  genes are influenced by growing conditions for each generation.

[shaneatwell]

This question has been bugging me for a year.

Heirloom plants are ones that when self-crossed produce progeny that are identical to the parents. They are developed by self-crossing and selecting for many generations (usually seven or more) until all the genetics are homozygous, i.e. 'fixed'. That is, genes on the two copies of every chromosome are the same (as opposed to having heterozygous dominant + recessive pairs). Thus all the self-crosses are the same as the parent because there's no diversity of genes. Heirloom plants are used by gardeners because they can replant seeds every year instead of buying new ones.

Is this ever done with fruit trees? There's not really the need and by the time you did it, your variety would probably be passe, but still. Anyone know? When I google for heirloom fruit trees all I get are varieties that have been grafted for decades, not at all the same meaning as for e.g. tomatoes.

I think that's a bit of a complex question. Let me start by making a few short points. First it's not true that all heirloom vegetables are all fixed. I remember having grown some that were not stable and so produced different looking fruits. With vegetables usually you have either annual or bi-annual plants. I think it's much easier to stabilize them then it is with perennial plants, such as fruit trees. Also there is the important consideration of whether a plant is self pollinating or cross pollinating, in terms of how easy it is to stabilize the traits. Many vegetables are self pollinating, but not all. So i think the self pollinating ones would be easier to stabilize in just a few generations. Many fruit trees depend on cross pollination so will have more variation and not be so easy to stabilize. Some fruits that are produced asexually are very easy to stabilize, like bananas. Maybe i haven't answered your question very well, as i'm not a geneticist, but i think it's a starting point.

All good points. My eyes were opened on the topic by Deppe's Breed Your Own Vegetable Varieties.
http://www.amazon.com/gp/product/1890132721/ref=wms_ohs_product?ie=UTF8&psc=1

With regard to your heirloom veggy seeds that didn't grow true, they might not have been heirloom. There's a fair amount of complaining in that community about people selling seeds as heirloom that are not.

But I guess the main point is that there are so many difficulties with trees and so much easier ways of propagating a true cultivar that there's much less reason to make heirloom trees. I still wonder if anyone has bothered to try.

The closest I've come across is perhaps Lamb Hass. Its lineage is something like Hass - (open pollinated) -> Thille - (backcross to Hass) - > Gwen - (backcrossed with Thille) -> Lamb Hass. The major differences with a true self-crossing lineage are 1) don't know what the actual crosses are (could be self, could be back-crosses, could be out-crosses). 2) the progeny weren't selected to be identical in all measured characteristics to the parent or Hass. 3) they are in fact quite different in some respects, especially color and season and to some extent size. However the Lamb Hass probably has fewer undesirable recessive genes due to having gone through 3 generations of selection for what amounts to pretty similar fruit. Anyone out there have a lamb hass seedling thats grown true to its parent?

[shaneatwell]

Most of citrus varieties (there are only very few exceptions, like for example citrus grandis - pomelo) can produce  nucellar seedlings, which are as you said in fact clones of the mother plant.

and by the way:  we recognize phenotype and genotype! . So, I do not believe that seedling from heirloom tree is necessary identical (clone)  to its grandparent, because  genes are influenced by growing conditions for each generation.

Yes, there are fruit trees that produce clones, most citrus and asian mangos being the two most obvious. Even more difficult to produce self-crosses (how would you even find them?) in these cases and less reason to do so.

I think what you're trying to say in that last sentence is that even clones will grow differently, which is true. I believe plant breeders propagate multiple lines in parallel to protect themselves from this.

[Radoslav]

I want to say, that living conditions affect genom - result is called phenotype, so each generation, especially, if plant grows in a bit different place than previous generation, has slightly different genom, so no matter how the seed was produced, even clones can be identical to mother plant, but not identical to grandmother plant.

[fruitlovers]

This question has been bugging me for a year.

Heirloom plants are ones that when self-crossed produce progeny that are identical to the parents. They are developed by self-crossing and selecting for many generations (usually seven or more) until all the genetics are homozygous, i.e. 'fixed'. That is, genes on the two copies of every chromosome are the same (as opposed to having heterozygous dominant + recessive pairs). Thus all the self-crosses are the same as the parent because there's no diversity of genes. Heirloom plants are used by gardeners because they can replant seeds every year instead of buying new ones.

Is this ever done with fruit trees? There's not really the need and by the time you did it, your variety would probably be passe, but still. Anyone know? When I google for heirloom fruit trees all I get are varieties that have been grafted for decades, not at all the same meaning as for e.g. tomatoes.

I think that's a bit of a complex question. Let me start by making a few short points. First it's not true that all heirloom vegetables are all fixed. I remember having grown some that were not stable and so produced different looking fruits. With vegetables usually you have either annual or bi-annual plants. I think it's much easier to stabilize them then it is with perennial plants, such as fruit trees. Also there is the important consideration of whether a plant is self pollinating or cross pollinating, in terms of how easy it is to stabilize the traits. Many vegetables are self pollinating, but not all. So i think the self pollinating ones would be easier to stabilize in just a few generations. Many fruit trees depend on cross pollination so will have more variation and not be so easy to stabilize. Some fruits that are produced asexually are very easy to stabilize, like bananas. Maybe i haven't answered your question very well, as i'm not a geneticist, but i think it's a starting point.

All good points. My eyes were opened on the topic by Deppe's Breed Your Own Vegetable Varieties.
http://www.amazon.com/gp/product/1890132721/ref=wms_ohs_product?ie=UTF8&psc=1

With regard to your heirloom veggy seeds that didn't grow true, they might not have been heirloom. There's a fair amount of complaining in that community about people selling seeds as heirloom that are not.

But I guess the main point is that there are so many difficulties with trees and so much easier ways of propagating a true cultivar that there's much less reason to make heirloom trees. I still wonder if anyone has bothered to try.

The closest I've come across is perhaps Lamb Hass. Its lineage is something like Hass - (open pollinated) -> Thille - (backcross to Hass) - > Gwen - (backcrossed with Thille) -> Lamb Hass. The major differences with a true self-crossing lineage are 1) don't know what the actual crosses are (could be self, could be back-crosses, could be out-crosses). 2) the progeny weren't selected to be identical in all measured characteristics to the parent or Hass. 3) they are in fact quite different in some respects, especially color and season and to some extent size. However the Lamb Hass probably has fewer undesirable recessive genes due to having gone through 3 generations of selection for what amounts to pretty similar fruit. Anyone out there have a lamb hass seedling thats grown true to its parent?

Some recognized herilooms can be unstable. For example, Moon and Stars watermelon can have varying amounts of splotching on outer rind. I think this trait is caused by a mutation, which is not completely stable. Similar to instability of Ae ae banana variegation.
Vegetables are obviously easier to breed than fruit trees due to their much shorter growing cycle. Luther Burbank devised some ways around this by grafting on seedling scion wood onto mature cocktail trees, which forces them to fruit much earlier. Also he could do trials of many cultivars on just one tree. I think if you read some of his books you might get the answer to your questions. Certainly you will at least get a lot of inspiration to make fruit tree trials.
Are you confusing perhaps trait stability with a genetic clone? A cultivar can be stable even though it is not produced asexually. Also as already pointed out by Radoslav, growind conditions will affect traits of plants, even when they are clones. I think this can be clearly seen for example in clones of lychees grown in different areas that express themselves differently.
As you hinted in your first post, heirloom vegetable is different than an heirloom apple or heirloom fruit tree. The first does imply some stability, but for fruit trees i think it just means a very old cultivar.