How to breed Bananas for Temperate climates

[SoCal2warm]

This post is about how to breed seedless bananas for temperate climates, a rough outline idea.

Select a cold-hardy banana (such as Musa basjoo) and then select another "edible" (good tasting, but seeded) banana which is very early ripening (perhaps Helen's hybrid).

Treat the apical bud with either Colchicine or Oryzalin to double to chromosome number, obtaining a tetraploid.


"Tetraploid plants were induced successfully from diploid bananas Musa acuminata ‘Kluai Leb Mu Nang’ and ‘Kluai Sa’ (2n = 2x = 22) with in vitro oryzalin treatment. Calluses from in vitro-grown shoot tips of both cultivars were treated with oryzalin at concentrations of 1.5 or 3 mg l−1 for 24, 48 and 72 h, respectively. The oryzalin treatments produced tetraploids at a frequency of 15.6% in ‘Kluai Leb Mu Nang’ and 16.7% in ‘Kluai Sa’ as detected by flow cytometry. Chromosome counting showed that the tetraploid plant chromosome number was (2n = 4x = 44). The selected tetraploid plants were transplanted in the field and variations in the morphological characteristic of leaf shape and fruit bunch compared to normal diploid plants were found under the same growing condition even after 3 years of cultivation."

In vitro induction of tetraploid plants from callus cultures of diploid bananas (Musa acuminata , AA group), Kluai Leb Mu Nang, Kluai Sa


Here's another relevant article as well: http://hortsci.ashspublications.org/content/43/7/2248.full


When a normal diploid is bred with a tetraploid, the result is a seedless triploid variety.


"Most bananas purchased at your local supermarket came from sterile triploid hybrids."
https://www2.palomar.edu/users/warmstrong/hybrids1.htm

[SoCal2warm]

I have another idea also.
Take a regular seedless banana (3n), double its chromosome set number to 6 (hexaploid), then breed it with another banana.
Once the chromosome set number has been doubled from 3 to 6 it should then produce seed because 6 is an even number (and the chromosomes can be evenly split during meosis).
Hybridizing a 6n (hexaploid) with a seeded 2n (diploid) should give a 4n (tetraploid) banana (also seeded), which could then in turn be hybridized again with a 2n seeded banana to give a seedless 3n triploid.
I believe it could also be possible to use seedless (3n) banana pollen to fertilize a hexaploid (6n) flower, also resulting in tetraploid (4n). I'm not exactly sure about bananas but this type of phenomena can work in citrus. There are some issues with trying to breed triploids but in general some normal (1n) haploid gametes are able to form from the meosis of triploids, and the majority of offspring able to form from triploids will be the same as if they came from a normal diploid parent (though the rate of fertility is normally substantially lower). Basically 3 is unable to split evenly into two, so some 1n gametes are able to escape from the division intact. Maybe someone with more knowledge than I will be able to give some input about whether seedless bananas have fertile pollen.


Edit: A quick search reveals triploid bananas can produce fertile pollen.

"Pollen viability was examined by recording the number of viable as well as non-viable microspores in anthers just before anthesis, as it could be an efficient and rapid indicator of female fertility. It was thought that competency in meiotic restitution in microspores could indicate similar competency in megaspores. Pollen fertility was compared among seeded diploids and edible triploids of Musa and correlated with ovule fertility. Viability was examined using the Alexander's pollen stain procedure. The seeded diploid species M. acuminata, M. balbisiana, and M. ornata had 3 times more viable pollen than the edible tetraploids (AAAB). M. balbisiana and M. ornata had significantly more viable pollen than M. acuminata. The tetraploids contained 3 times more viable pollen than the edible triploids AAA […] The AAA triploid Gros Michel had the highest percentage of viable pollen at 13% […] "

Pollen fertility in Musa : Viability in cultivars grown in Southern Australia, J. A. Fortescue, D. W. Turner, Australian Journal of Agricultural Research, January 2004

[jako9403]

Damn... This is advanced!

[lebmung]

If Colchicine which is used as a medicine to treat people, induces mutations in bananas I wonder what happens to people who take it.
Very interesting.

Protoplasm fusion should yield something as well.
Are you going to make those experiments?

[druss]

So a few points;
The goal of a cold climate banana can be reached two ways,

The first most talked about way is using a cold hardy wild sp such
as basjoo. There is debate as to whether previous crosses were actually acuminata x basjoo as theyve been impossible to recreate thus far. However there are other more likely sp such as griersonii, sikkemensis, yunnanensis  some high altitude itineran sub sp and even some extremely high altitude acuminata discovered in china. It should be noted that edible types of bananas with cool hardy balbisina genes are tougher than pure acuminata types.
The second would be to use short cycle bananas  in the rhodoclamys subsection. These are smaller plants that grow and fruit much faster than the musa subsection. Id suggest arunachalensis, ochraceae or rubinea would be good candidates.
You could get a smaller plant with smaller bunches but one that would grow flower and fruit in the spring summer autumn of your climate before dying back to corm over winter.

Once you decide on which way you want to go them you need to look at breeding methods.  Most common are 4 x 2 and 3 x 2 then 2 x 2. Given that domestic bananas are more pollen fertile than ovule fertile it makes sense to use your wild sp as the mother plants.
For 4 x 2 start with a pollen donor like fhia02 an AAAA and cross it with your cold tolerant yunnanensis for example, straight off the bat you should get AAY triploids with increased hardiness and a good chance of being parthenocarpic and sterile. If you have access to a flow hood and the associated sundries you could double the yunnanensis to YYYY and cross it with sh3142 an AA, this will give most likely a YYA but possibly YYAA assometimes acuminata chromosomes in ovules dont reduce. The YYA will be more hardy but less likely to be sterile and parthenocarpic, but it is possible  just as in ABB bananas.

The 2 x 3 can be done both ways. Take pollen from a wild sp such as griersonii and pollinate something like igisahire gsanzwe a reasonable fertile triploid AAA. You will get either AG,AAG or AAAG. Igisahire is also pollen fertile so you could pollinate your wild griersonii and end up with the same end combos.
 If you want more than one cold hardy sp in your mix, theres a couple of ways.
One is th cross the wild sp first  say ochracea x sikkemensis to give an OS diploid, then chromosome double it to an OSOS. Use the haploid pollen onto your sh3142 or other domesticated diploid to get an OSA triploid.
Another is to repeat the same with your GA hybrid offspring, double it to GAGA then cross it to Yunnanensis for a YGA triploid.
Lastly you could take your GA or OS pollen and use it on igisahire  if your lucky yuo might get an AAGA or AAOS tetraploid. This could be done with any combo. Odds are you will need to allow for multiple crosses and back crosses to get a winner. Allow 20 years or so.
As a note  tetraploids are the highest common ploidy in bananas
Higher ploidy is possible but has shown to be a dead end.

[knlim000]

too much writing.  Can we just see the video of how to do it?

[SoCal2warm]

I just read that Cavendish is a little bit of an exceptional category of bananas. Other seedless bananas, like Gros Michel, might only produce two or three seeds per bunch (due to triploidy) but Cavendish is exceptionally female-sterile. However, even Cavendish is not completely female-sterile; about 1 seed per every 100 bunches of bananas will form if pollinated by a different Cavendish variety. Which explains why we never see seeds in the bananas at the supermarket.

[druss]

Most bananas show a similar level of sterility, cavendish takes it to extremes but most domestic varieties are rated at less than 5 seeds per commercial bunch when pollinated with highly fertile pollen. Once you add in male flower non overlap due to mono variety planting, male bud removal and environmental factors, seeds in bananas become like hens teeth.

[SoCal2warm]

There may be another way of obtaining a tetraploid banana without Colchocine or Oryzalin.

"Crossing of a triploid banana with a diploid variety generates diploid, triploid, tetraploid, aneuploid and hyperploid progeny"

I believe this may be because sometimes an unreduced gamete escapes, and in the case of triploids, an unreduced gamete (still with all 3 sets of chromosomes) is much more likely to escape meoisis intact and be viable than a triploid that underwent chromosomal division.
So an unreduced 3n gamete from pollen + a normal haploid gamete from the female parent = a tetraploid offspring 4n

https://www.sciencedirect.com/science/article/pii/S0254629905000463#bbib22

I know the same thing can occur in citrus but it's usually only somewhere around 1 out of 25 offspring.

Another article seems to suggest with bananas it may be as high as half:
"On the assumption that Cavendish cultivars have low fertility, the Banana and Plantain Breeding Program at the Honduran Foundation for Agricultural Research (FHIA), starting in 2002, pollinated 20,000 bunches, approximately 2 million fingers, of the Cavendish cultivars ‘Grand Naine’ and ‘Williams’ with pollen from 10 Cavendish cultivars for the development of Cavendish tetraploids. As a result, 200 seeds with 40 viable embryos were obtained, from which 20 tetraploid hybrids were developed. These results confirmed the assumption that Cavendish cultivars have low fertility, which allows their use in conventional breeding methods to create new progenies. The selected tetraploid progenies were crossed with improved FHIA diploids for the development of second generation triploid hybrids."
http://www.fhia.org.hn/dowloads/banano_y_platano_pdfs/Improvement_of_cavendish_banana.pdf

much of this is because seeds that would have had problematic chromsomal abnormalities don't form in the first place, i.e. half the seeds that do manage to grow from a normal seedless banana, out of the very few number of seeds, will be tetraploids. Then these tetraploids can be crossed again with a normal (diploid) seeded banana to give a seedless banana offspring.

[druss]

Yes the 2 x 3 method or 3 x 3 if you want can get you tetraploids, ad I mentioned above. Then they can be reduced to triploids eith the 4 x 2 cross.

[lebmung]

I grow  M. balbisiana from a seed collected from a forest which is very strong and hardy, it continues to grow under low light and cold 5C. Flowering can take up to 3 years.
On the other hand Musa acuminata ‘Kluai Leb Mu Nang’ I have it's the most sensitive to cold and light. it stops growing and yellowing under 15C. The advantage is fast flowering in 6-8 months.
A protoplasm fusion of both would be interesting.

[druss]

Many domestic bananas are just that. Look for types that are : AB, AAB, ABB, AAAB, AABB or ABBB.

[ricshaw]

In the mean time try a Dwarf Namwah.  Works for me.  Plenty of good fruit, grows well in coastal Southern California.

[lebmung]

I have 10 varieties of bananas
Musa acuminata (AAA) ‘Dwarf Cavendish’
Musa sikkimensis (Darjeeling Banana)
Musa sapientum Linn. (AA) 'Kluai Leb Mu Nang'
Musa balbisiana ‘Kluai Tani’
Musa basjoo
Musa (ABB) "Dwarf Orinoco"
Musa (AAB) "Dwarf Puerto Rican" (plantain)
Musa acuminata (AA) 'Siam Ruby'
Musa (ABB) ‘Kluai Nam Wa Dam’
Musa (AA) ‘Kluai Khai’ ( Sucrier)

From all of these Musa balbisiana is the strongest in terms of resistance/pests/disease for my climate, they are all in pots.

[SoCal2warm]

I have 10 varieties of bananas
Musa acuminata (AAA) ‘Dwarf Cavendish’
Musa sikkimensis (Darjeeling Banana)
Musa sapientum Linn. (AA) 'Kluai Leb Mu Nang'
Musa balbisiana ‘Kluai Tani’
Musa basjoo
Musa (ABB) "Dwarf Orinoco"
Musa (AAB) "Dwarf Puerto Rican" (plantain)
Musa acuminata (AA) 'Siam Ruby'
Musa (ABB) ‘Kluai Nam Wa Dam’
Musa (AA) ‘Kluai Khai’ ( Sucrier)

Can any of those grow outside where you live? (I mean left in the ground during the Winter)

[lebmung]

The top dies. The temperature can drop to -18C in the night for few days.
Musa sikkimensis and Musa basjoo rhizomes survive in the ground if covered.
Musa balbisiana is a strong candidate until -1C. The Musa balbisiana ‘Kluai Tani’ I grow it from a seed colected in a forest in northern Thailand where temperatures can drop to 2-3C. Not to be confused with Musa balbisiana ‘atia black’ which has a black stem and seeds are readily available in seed shops.

[SoCal2warm]

Here's a Helen's Hybrid seedling that I grew from seed


I also grew some Thomson's Edible (Musa thomsonii) from seed, which looked like an interesting uncommon species, so we'll see how hardy that is. One source said they survived 7b in North Carolina unmulched and came back.