Sunday, April 24, 2011

The Canarian banana: a tasty narcissistic triploid

Although the title may seem odd to you, in fact perfectly defines this giant grass. Its scientific name is Musa acuminata var. Dwarf Cavendish and is the result of a curious process of reproduction of a plant with itself followed by a dwarfing mutation. The delicious Canarian banana is thus a dwarf auto-hybrid.. 

Banana plantation in Los realejos of Tenerife. The bananas are braced to prevent the weight of the cluster lie. (Double click on the photo to enlarge)

Its original ancestor was an Asian wild banana, probably in the Indomalayan region, Musa acuminata, with a normal AA diploid chromosome and a fruit-filled chewy and inedible black seeds. A mutation in the germ cell of a flower disrupted the process of meiosis (which is usually divided by half the chromosome of the germ cells giving rise to haploid gametes A) and instead meiosis there was a mitosis. Plant genetic disorder is called Apomeiosis, ie absence of meiosis. As a result of this change a bunch of flowers of Musa acuminata mutant produced diploid ovules and pollen. Chance led to self-pollinate the flower with its own pollen and plantain seeds grew full of autotetraploid AAAA with two identical complete genomes, that is, the sum of AA genome diploid pollen and diploid AA genome of the ovule. 

Plant breeding this chromosomal aberration is perfectly viable, but often produce sterile plants. Many cultivated plants are polyploid (triploid, tetraploid, hexaploid, etc. ..), since its polyploidy them very effective and produce much larger fruits and tasty. An example is the bread wheat, Triticum aestivum, a hexaploid product of a spontaneous hybridization took place some 2,000 years ago, the grains are much larger than those of wild wheat. The giant strawberries and tomatoes are also polyploid. 

In animal and human genetics are also produced chromosomal aberrations polyploidy complete, but the embryos are not viable and die producing a spontaneous abortion. Sometimes the only surviving trisomies (Down syndrome, Edwards, Patau, Klinefelter, etc ...) and haploidy (Turner syndrome) in a single chromosome, but never complete polyploid.

Inside a banana plantation in Los Realejos. The Canary banana is characterized by its small size, a very thick stem at the base and high productivity.

Inside another banana plantation in Tazacorte on the Canary island of La Palma.

After making a random wild banana seeds full of autotetraploid, one of the seeds germinated and gave rise to an embryo with four banana AAAA identical genomes. Again the chance was a native discovered the banana autotetraploid, whose bananas were bigger, with more pulp and seeds were not, being sterile. Not being able to reproduce by seed, turned to the division of its rhizome and thus was born the first planting Asian banana.

Musa acuminata autotetraploid, genetic grandmother Canary banana, grown in the Botanical Garden of Funchal in the Madeira Island. It is a giant grass about 4 feet high, very strong as most hybrids with small bananas not seeded.

Same banana previous autotetraploid. The clusters are less bananas Canary Dwarf Cavendish variety. 

The new banana AAAA did not produce seeds, but their pollen is viable and fertilized a diploid flower of a wild Musa acuminata nearby forest. The result of this retro-hybridization was a banana with AAA triploid seeds. (Diploid pollen AA x Haploid ovule A = Triploid seeds AAA). 

Again fate played into the man and a hybrid seed germinated and gave rise to a triploid banana  with large, flavorful and seedless fruits, that they matured pathenocarpically without being fertilized. Had been born the Cavendish variety, the progenitor of the Canary banana. 

Beautiful image of a large banana plantation along the Atlantic Ocean at the foot volcanic Barlovento town on the island of La Palma. 

In the Canary Islands were built huge rafts over the banana plantations so they could be watered by gravity without any pumping machinery. The banana trees are planted in terraced, following the topography of the volcanic slopes. Each farmer has owned a few hours per week of irrigation water with his own pipe connected to the community pond and a stopcock padlocked to prevent theft of water. The tangle of intersecting tubes is spectacular. "Acequiero" only able to know who owns each pipe and each lock. 

A spontaneous mutation in germinal meristem of a rhizome of the new Musa acuminata var. Cavendish banana resulted in a smaller, thicker stems, very productive, resistant to sub-cool winters, with high quality fruits, the dwarf banana Musa acuminata var. Dwarf Cavendish. Its hardiness and excellent qualities of his favored bananas growing and expanding all subtropical areas, including the Canary Islands, where he found an ideal climate for cultivation. 

The rhizome will produce shoots that grow to flowering and fruiting. Once the bananas have ripened, the stalk dies and is replaced by one or more new shoots. In the photo of a banana Tazacorte can see a cut stem which has already borne fruit, a stem that is bearing fruit and a small tiller that will replace it. 

The cluster of Canarian banana flowers of three types. The first 5 to 15 rows of female flowers are open and barren, very rich in nectar and ripe fruit by parthenocarpy without being fertilized. After opening several rows of hermaphrodite flowers and finally near the top of the bunch is fertile male flowers open. Banana farmers to avoid unnecessarily weaken the banana and at the same time reducing the enormous weight of cluster apical cut the hermaphrodite and male flowers and leave only the parthenocarpic female flowers. 

Parthenocarpic female flowers of the Canary banana her long, thick pistil surrounded by two white tepals: the upper is longer than the pistil and the shorter lower. These pistils are cut with a special knife with the intention of facilitating the fattening of the fruit and give a better look at the bananas at the time to market.

Large cluster of bananas from the Canary Islands with the apex and floral styles cut, ready to be collected for shipment to markets in the rest of Spain where they are greatly appreciated. They are usually harvested when they have not yet reached their peak of ripeness. This will facilitate transportation. Once they arrive at the markets and the homes of consumers end maturation in a few days.

Currently in the Canary Islands are grown other varieties adapted to subtropical climate, such as the Great Dwarf, and in recent years are experiencing the growing of two local teams called Brier and Gruesa.
In tropical countries, cultivated the call male plantain, Musa x paradisiaca, which produces large banana takes seedless pulp, unfit to be eaten fresh, but of excellent flavor when fried or baked. The plantain is a natural hybrid between Musa acuminata and Musa balbisiana.
In frost-free Mediterranean climates is grown the called garden banana, Musa x Orinoco, a hybrid able to withstand the cold winters of the coastal areas of the Mediterranean basin, where it rarely reaches freezing. 

  Ideally, the Musa x Orinoco is 4 meters high. To withstand the long, dry and hot summers of the Mediterranean requires abundant irrigation weekly. In winter, cold and wind burn their leaves, but when temperatures rise again in April re-sprout new leaves and blooms in midsummer with a small cluster of red flowers. 

  Parthenocarpic female flowers of banana garden with its pistil surrounded by red tepals. They have no stamina. (Photograph taken in a garden in the Valley of Soller on Mallorca) 

Hermaphrodite flowers of banana garden with five stamens and a pistil. (Photograph taken in a garden of Sa Pobla on Mallorca) 

Hermaphrodite flower of Musa x Orinoco with two reddish tepals around the 5 stamens and pistil. 
Small, thick and tasty bananas of Musa x Orinoco, with a sweet juicy pulp.

And to finish with good taste, here I put the recipe for a delicious dessert easy to prepare: 

Canary bananas fried with honey, sesame and pine nuts: 

A little butter or vegetal oil is put in a frying pan and the pine nuts are toasted. When they have taken a toasted color, the sesame is added and next a pair of spoonfuls of honey, lowering the fire to the minimum. Two or three bananas by person are peeled and add to the frying pan upon the other ingredients, to the three minutes return them and they are left other three minutes, always to sweet fire. They are delicious.

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