last week, the Columbia Institute of Agriculture confirmed that bananas in four plantations in the northern part of the country were suspected to be infected with Fusarium oxysporum (TR4). Banana samples from these plantations were sent to the laboratory for genomic analysis, and the final analysis results will be available in early August.
were first found in Southeast Asia and have spread to the Middle East and Africa. Since bananas have little resistance to TR4, their large-scale outbreak will bring a devastating blow to banana plantations and raise banana prices worldwide. Some scholars have pointed out that TR4 in central and South America is difficult to control, and many individual farmers will not be able to afford the control measures.
banana’s past and present life:
one of the most difficult fruits to cultivate in human history,
a line written by kongzhi Yingqiu, author of silver soul, was once very popular on the Internet: “we ordinary people, just living, have to do our best.”
this time, we are going to use this sentence to describe an equally common fruit – banana.
banana is the favorite fruit of many people. It has sweet taste, pleasant color, low price, high yield, easy storage and transportation, and is widely favored by consumers and growers. At present, banana is cultivated in Asia, America, Africa and along the equator of Oceania. It is the second fruit in the world (the first is watermelon), with a total annual output of more than 100 million tons. In other words, the average person in the world consumes about 30 jin bananas a year. At present, the main banana producing areas in the world are “30”
, “India”, “Indonesia”, “Malaysia” and “Philippines”. The Honduras, Panama, Brazil and Costa Rica in the Americas, Rwanda, Burundi and other “brother
” in Australia are also known as
. The ubiquitous plantations and low prices of
make bananas look ordinary. But few people know that banana is one of the most difficult fruits in the history of human crop domestication. In the history of
, banana has suffered from several genocidal crises for several times, and it has reached the current planting scale only after several generations of hard cultivation and continuous variety improvement. It can be said that the past and present life of banana is a proper portrayal of the saying “to live, you have to do your best”.
who was the first to eat bananas? At present, it is believed that banana originated in Papua New Guinea in the Pacific Ocean. The island has unique soil conditions and climate and water environment, which is particularly suitable for the growth of Musa plants. The wild banana trees on the island are extremely tall, and the fruit is enough for the local aborigines to feed on.
at present, the residents and aborigines in PNG still keep the tradition of planting banana trees. The banana trees on the island can be as high as 20 meters, and the bananas produced can be up to 30 cm long, and the weight of a single root is more than 4 jin. This may be the earliest record of banana cultivation in a broad sense.
giant banana trees and mature bananas in PNG. The giant banana contains a large number of seeds (c), and the local people propagate the banana by planting and cutting. This giant banana is a local wild banana variety that has been bred and preserved by local people after natural variation (photo from 9 gag.com ）
China also has a history of wild banana cultivation. Wild banana and wild Musa were collectively referred to as “Musa” in ancient times, which were important cultural elements.
are easy to throw people away. As an important cultural symbol written by the ancients, bananas can be traced back to before the Southern Song Dynasty. However, in the following thousands of years, the cultivation of Musa plantain in in China remained at the stage of poetry, poetry and landscape, and did not develop to the edible aspect. Therefore, although “spkds” and “spkds” are not the origin of banana, they are not the same as “spkds”. In the 14th century, with the introduction of Islam into Indonesia, East Asia, including Indonesia, became the birthplace of modern banana cultivation. After the establishment of
edible banana varieties, along with the migration of Islam, spread to the west, successively in Africa and Madagascar, and then were brought to South America and the Caribbean in the flood of Portuguese colonization. After going around, banana cultivation spread to Southeast Asia and Australia through South Asia, and finally settled down in Yunnan.
have been cultivated in Papua New Guinea and China for thousands of years. However, the banana widely planted in the world (such as Chinese banana) is an artificial cultivar originated from East Asia. Therefore, although there are abundant wild banana resources in China, the banana planted at present is imported.
in the long way of transmission, with the different climatic conditions and long-term artificial breeding around the world, the first two wild Musa varieties crossed and mutated with each other, forming several banana varieties. These different banana varieties can be traced back to two original wild Musa species before 8000 BC: Musa acuminata and Musa balbisiana. The small fruit banana is sweet but has many seeds; the wild banana is soft and sticky but sour and astringent – so that although the two wild bananas were recorded in Yunnan and other places in China as early as the Han Dynasty, few people used them as a kind of food.
has long been discovered in crop breeding: chromosome doubling occurs in many plants when they are stimulated by unknown environmental substances (such as low temperature, radiation and chemical agents), that is, all the original genetic materials (collectively known as genomes) in cells are doubled or even doubled. For these plants, because the genes controlling growth, nutrition and sugar synthesis are more than doubled, the plants tend to have stronger stems, larger leaves, fruits and seeds, and significantly increase the contents of nutrients such as sugar and protein.
are the most common genomes of wild bananaThey are called group A chromosomes and B chromosomes. At present, the gene status and morphological characteristics of the main banana varieties. Among them, the main edible varieties of Chinese people are Huajiao and Fenjiao. Both of them are artificially bred banana varieties, but they are two species in taxonomy. (the source of the picture is in the reference materials, with some changes)
at present, the bananas we have seen in the market (generally Musa cavendihii) and Musa NGU (also known as Xiaomi Jiao and Saigong banana) are triploid bananas after chromosome doubling caused by anti complex cross between wild banana and wild banana.
the banana cut by Zhang in the above picture is clearly edible banana, and there is no “wild” theory at all. Because triploid is a highly sterile cultivar, the planting method can only be cuttings. Each plant is a lateral bud cut by fruit growers on the mother plant (modern agriculture often uses tissue culture method to propagate seedlings), and it is formed by hardworking after cutting and rooting. From cutting to seedling growth, banana can be produced for more than a year. It is no wonder that local fruits can be stolen in a reasonable manner Farmers are so angry.
banana generation history
banana disaster and survival
banana may be strange to many people. At present, there are a variety of watermelon, apple and orange on the market, but there is only one banana we can buy (Huajiao)? This is due to a pathogen called Fusarium oxysporum f sp.cubense , FOC).
banana fusarium wilt belong to soil fungi. The disease caused by Banana Fusarium wilt is commonly known as banana panamania disease. Under the microscope of
, the morphology of Fusarium oxysporum f. sp. was strange banana shape (a). The disease would cause a large number of banana trees to die. The pathogen could spread to the nearby banana forest and continue to infect other banana trees (b). Banana trees infected with the disease suffer from brown rot from inside to outside and quickly wither (C-E), which often leads to large-scale production reduction and death of banana forest (photo source, see references, with changes).
in the mid-20th century, a banana variety named Gros Michel was once popular in banana planting industry. Nowadays, many banana milk drinks are flavored by artificial flavors based on the flavor of big Mike banana. In fact,
were planted in America, Africa and Europe as early as the beginning of the 19th century, and once exported to all parts of the world. However, in the 30 years since 1927, banana fusarium wilt No.1 has spread in some areas. Because people did not know enough about the transmission route and defense of the pathogen and prevention and control experience at that time, Big Mac banana disappeared in America and Africa, leading to the bankruptcy of numerous farmers, and the American people once had no bananas to eat. After the
were wiped out by the Big Mac, breeders had to speed up the search for alternative banana varieties. Huajiao and Fenjiao, which we eat today, were the candidate banana varieties as “substitutes”. The reason why Chinese banana was called a substitute was that it was found that it had enough resistance to species 1 that ravaged the world and could continue to be planted in plantations contaminated with spores.
babies who are familiar with the theory of evolution must know that in natural selection, only sexual reproduction can produce random variation, and environmental pressure (such as disease invasion) can select beneficial mutations (such as disease resistance). However, in asexual propagation, the genetic material of offspring almost does not change with the increase of reproductive generations. As Chinese banana is mainly propagated by cutting, all the Chinese bananas planted in the world are the asexual progenies of the same plant. Therefore, once a new pathogen starts to infect the banana, it will probably be destroyed like the Big Mac.
banana is going to be extinct?
at the end of 2017, the saying that “bananas are going to be extinct” on the Internet came from this. As the best substitute, Huajiao has finally met its “enemy”: Fusarium oxysporum sp. 4 (TR4). What’s terrible is that TR4 can infect almost 95% of the commercial varieties at present, and the only banana with certain resistance to TR4 is actually an embarrassing ornamental variety.
so, is banana really going to be extinct?
The answer to
may not be so pessimistic. The development of modern agriculture has made rapid progress. Although it is only half a century after the defeat of MAC, many new planting methods and new pesticides have been mature, such as using tissue culture to propagate aseptic banana seedlings, setting up isolation belts between plantations, rotating with sugarcane and regular inspection, etc., which are used as effective tools to resist TR4 erosion It has achieved remarkable results in the field. Another alternative to
is to plant bananas in Greenhouse in the north. At present, China has carried out greenhouse banana cultivation technology in Sichuan, northeast, Xinjiang and other places. Due to the closure of the greenhouse, TR4 pathogen has been basically completely suppressed. The third way of
is to breed new banana varieties by cross breeding. For example, “fhia01-04” series bred by fhia of Honduras agricultural research foundation, gctcv-119 (kangku No.5 banana) introduced from ITC in China, and “8818-1” TR4 resistant banana cultivar bred by Xie Jianghui Bo, Institute of south subtropical crops, Academy of Tropical Agricultural Sciences, etc. These new varieties of banana have better disease resistance adaptability and higher yield. At present, it has been planted commercially in some areas of China. The fourth method of
is to carry out transgenic on the original banana varieties with high yield. For example, James Dale, a biotechnology expert at Queensland Polytechnic University in Australia, and his colleagues have found a wild banana that is immune to TR4. Since the current banana varieties are sterile and can not be hybridized, the rga2 resistance gene cloned from wild banana varieties was transferred into Huajiao, and more than 6 resistant lines with different degrees of resistance were obtained.