Author Topic: monoembryony inheritance question  (Read 543 times)

orangedays

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monoembryony inheritance question
« on: January 29, 2021, 11:39:33 AM »
I read this post on a citrus site

" Originally uglis were thought to be chance hybrids of mandarin and grapefruit. Closer examination of the various strands has shown that many parents are involved. Because of the monoembryony exhibited by the seeds, some botanists are of the opinion that a pomelo is the parent in question rather than grapefruit." -- http://citruspages.free.fr/pomelos.php

It seems that there is an idea about monoembryony quality of trees transferring to the offspring when the tree is used as the female parent.  Does  monoembryony transfer in that way?  Any ideas on how it segregates in mono x polyembryonic crosses?

- Thanks

Ilya11

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Re: monoembryony inheritance question
« Reply #1 on: January 29, 2021, 05:22:21 PM »
It seems that there is an idea about monoembryony quality of trees transferring to the offspring when the tree is used as the female parent.  Does  monoembryony transfer in that way?  Any ideas on how it segregates in mono x polyembryonic crosses?

No, polyembryonic feature is not inherited only from a female parent. It is determined by few codominant genes located in nuclear genome.
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« Last Edit: January 29, 2021, 05:31:32 PM by Ilya11 »
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orangedays

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Re: monoembryony inheritance question
« Reply #2 on: January 29, 2021, 06:40:07 PM »
Thanks,  those articles were very interesting.  If I understood them, it seems likely there are a few dominate genes that confer polyembryony.  So in a cross if two mono embryonic varieties are crossed then most of the offspring should be mono embryonic since these would be mostly homozygous recessive genes segregating.  That might be useful in breeding programs to avoid polyembryony as much as possible. But maybe the polyembryony confers better taste.

Ilya11

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Re: monoembryony inheritance question
« Reply #3 on: January 30, 2021, 04:04:19 AM »
It served in the past for the preservation of varieties since most of propagation was done by grains.
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orangedays

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Re: monoembryony inheritance question
« Reply #4 on: February 02, 2021, 06:19:49 PM »
Iiya, good point.  Polyembryonic seed made it possible to transfer clones of great tasting citrus around the world when travel was slow and difficult.  Citrus that were known to breed true to type, would be the preferred ones to start new groves from. It could hardly be more convenient for the orchardist and the best available material has been selected to be polyembryonic via this convenience. So taste may not be associated with polyembryony at all.

 Thank you and all the people on this forum for sharing so much knowledge. Its a lot to think through when hoping for a few pleasant tasting citrus to grow in zone 8a. The long term F1 breeding project started by Walt is especially interesting. You posted a link there, discussing the inheritance of sour vs sweet in citrus and also the information about the precocious poncirus not producing perfect flowers for several years. Not to say the pollen would not be useful. I had a lemon that behaved this way and was about to discard it last spring but it suddenly starting producing perfect flowers and so I saved it and got lemons. (as in fruit not bad results) The idea of developing a deciduous citrus from PT genes seems like the ideal solution to cold hardiness. Such complicated genetics to work through. But a really good solution.  I take to heart comments that after many years of breeding the results are still not satisfactory. I hope all the work from the breeding projects done by the forum members does not get lost. It seems that the cold hardy plants developed before 1930 are still the starting material for many cold hardy citrus breeders. There must have been intrepid gardeners between 1930 and 2000 breeding better cold-hardy citrus. But who know what happened to them?

This is a follow on question about polyembryony,  I made crosses last year using changsha as the citrus mother with citromelo, tanglelo, meyer lemon, and key lime as pollen. The majority of the flowers pollinated with citromelo and tangelo proceeded to fruit, and produced about 30 seed per fruit which is normal for this changsha.  The lemon on the other hand produced far fewer seed, around 7-8 per fruit and far fewer fruit actually took. The lime was the worst. Out of about 15 fruit, two set. One was completely seedless and the fruit very small the other contained only one large seed.

This winter when the seed were planted, the tangelo cross sprang up first and grew vigorously, the citromelo also followed and grew fairly fast. The lemon seedling came up very slowly and are growing slowly. Some creature broke into the green house, and chewed the lime seed to mush.  I estimate the actual number of zygotic seedling to be low (10-15%) based on the small number of plants with PT leaves among the citromelo seedlings. The thing that makes me wonder is that the number of plants germinating from each seed seemed to be affected by the pollen parent.  The changsha x lemon crosses were all mono-embryonic except for one seed which has two seedlings.  They came up as large seedlings but are growing very slow and a few seem to lack a meristematic buds. They put out three leaves and stop though the leaves get bigger. The difference in germination and growth could have been the soil, I used two batches of potting soil but the difference in number of seedlings per seed between the lemon and tangelo is odd. I would be glad to hear your thoughts on whether the pollen parent can effect the number of embryo's per seed or if this is just a coincidence.

Ilya11

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Re: monoembryony inheritance question
« Reply #5 on: February 03, 2021, 10:59:39 AM »
The varieties that you have used as  mother parent are largely nucellar.
Pollination results in the formation of a zygote secreting  growth factors that induce the formation of  a variable number of nucellar embryos.
This capacity as well as vitality of zygote embryo depends on its genetic composition that comes from both parents.
In many cases nucellar embryos  overgrow the zygote that dies.
That is why the presence/absence of a zygotic seedling and the variable number of nucellar ones  depends on both parents in such crosses.
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Till

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Re: monoembryony inheritance question
« Reply #6 on: February 12, 2021, 02:08:28 PM »
My experience with producing hybrids is much more limited than Ilya's. I used emong others the nucellar varieties Limequat, Calamondin, Vainiglia Sanguigno (an orange), Poncirus and Yuzu as mother plants. I would like to encourage everybody who is interested in hybridizing to just try combinations. Plants that usually produce nucellar seeds can also produce hybrids.
Calamondin x Poncirus is easy. There are a number of hybrids in polyembryonic seeds and a very small number of monoembryonic seeds with yellow colour (normal is green). It is interesting that the same Calamondin tree can produce (yellow) monoembryonic seeds, (green) seeds with few embryos, seeds with one yellow and some green embryos and (green) seeds overloaded with embryos. All seedlings that did not have trifoliate leaves looked exactly the same and were probably nucellar. That means Calamondin seems to produce only nucellar seeds, except it is pollinate by Poncirus (or certain other species that I did not test).
Yuzu x Poncirus gave rise to one hybrid (most seeds were lost :-(, I think there were more hybrids). Limquat x Poncirus results in an resonable number of hybrids. Limquat x Swingle5Star seems to lead to even more hybrids (tests not finished). I got one hybrid of Vainiglia Sanguigno x Poncirus out of a hugh number of pollinated flowers (sadly to say: the seedling died). Poncirus as motherplant almost compliedly failed, but last year one Poncirus tree was sucessfully crossed with Rusk Citrange (a few hybrids are already discernable).
It makes more fun to use motherplants that have mostly zygotic seeds but you should just try to use others also. Don't be disappointed but be always of good hope. As Ilya wrote the number of zygotic seeds also depends on the pollen parent. Find out what combinations work!

mikkel

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Re: monoembryony inheritance question
« Reply #7 on: February 12, 2021, 05:00:27 PM »
Most of the hybrids I have made have been with Ichang Papeda. Either as mother or as pollen donor. I have not found any polyembryonic seeds. I suspect that Ichang papeda has some ability to produce zygotic seeds.
But of course it is possible that I have only used zygotic mother plants by chance.

Ilya11

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Re: monoembryony inheritance question
« Reply #8 on: February 13, 2021, 09:00:28 AM »
Limequat Eustis gave many zygotic seeds.
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orangedays

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Re: monoembryony inheritance question
« Reply #9 on: February 13, 2021, 08:49:44 PM »
Till,  thanks for your input; it is very interesting to read about your crosses. I have had some success with polyembryonic citrus. At least with changsha. But with a poly-embryonic tangelo, I did not find any seedling that I can say are zygotes.  I saw the calamondin x poncirus seedling you posted earlier with a great deal of interest.  I had abandoned the idea of using calamomdin two year ago after reading the calamondin only produces clones.  Also because stripping anthers off the small flowers was difficult.  When I saw the image you posted I realized such a cross is possible.  The calamondin is a nice little plant, easy to grow and constantly in bloom when not ripening fruit.  I pollinated an Amber Sweet orange with the calamondin pollen a few weeks ago, inspired by your success. I hope it will make a cross. Probably both plants have green embryos so the color may not help me find the zygotes.   Do citrus embryos presents the phenotype of the embryo which is why it can be yellow like poncirus or green as expected for calamondin?  The embryo color difference would be very helpful in selecting out zygotes. I will have to survey my citrus collection to see what the embryo colors are. Changsha is definitely green but some of the poncirus crosses are yellow or tan.

orangedays

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Re: monoembryony inheritance question
« Reply #10 on: February 14, 2021, 05:08:13 PM »
Thanks for the information on the Ichang Papeda and the Limequat Eustis.  I will definitely add these to my collection, they both look like very useful plants.  I ordered a Hirado Pummelo to have the mono-embryonic quality with large fruit size as well.  I am looking forward to Spring.

mikkel

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Re: monoembryony inheritance question
« Reply #11 on: February 15, 2021, 02:27:12 AM »
Some Ichang Papedas seedlings and hybrids have even a shorter juvenile stage. I found seedligs of Lime Ichang, Citron Ichang, N1tri flowering within the first year. But only once. It is not stable. But some reached full maturity at the age of 4.
Bernhard Voss told me that he selected all his Ichang Papeda hybrids by early flowering. He said it happens quite often.
It is definately a path I will follow.
Lets hope this winter hasn`t killed them....