The agricultural scientists in our foodie country have "completed the new work" again! The world's first new variety of longan hybridization with lychee, "crisp honey" was born in the mainland!
No one in the world has ever done this, how hard is it to hybridize longan and lychee?
Reproductive isolation is what it is
Individuals of different species generally do not mate, and even if they do, they do not produce new fertile individuals. This is essentially a matter of level of reproductive isolation. That is, the isolation between different species is first manifested as behavioral isolation (sexual interest does not occur between different species); The second is genetic isolation. Genetic isolation is divided into pre-zygote isolation (sperm and eggs of different species cannot form zygotes' such as: sperm and eggs of chickens and rabbits cannot be combined) and post-zygote isolation (zygotes formed by sperm and eggs of different species cannot develop normally or the hybrid individuals who develop into heterogeneous individuals have no reproductive ability 'for example: mules have no fertility).'
However, in plant species 'reproductive isolation does not seem to be as strict as it is between animal species', some different plant species that are more closely related can produce new species in between through artificial hybridization. For example, hybridizing wheat and rye can produce a new species that does not exist in nature with both wheat and rye characteristics - small rye. Through selective breeding, small rye strains with both wheat yield and rye stress-resistant cattle can be obtained. This is of great significance in agricultural production practice.
Hybrids of lychee longan are being studied all over the world
Lychee and longan are the two most important trees in the Apocynaceae family 'Due to the tall body' of the tree's long childhood' genetic composition is highly heterozygous' Conventional breeding progress is relatively slow' But since the 1980s ' especially since the mid-1990s ' Domestic and foreign fruit tree workers have carried out a lot of biotechnology research on it ' at the cellular level and DNA molecular level has made great progress.
In addition, agronomists believe that lychee and longan belong to the genus lychee and longan of the family Apocynaceae, which have many complementary favorable genes in terms of fruit maturity, fruit size, stress resistance, etc. If the genes of lychee and longan can be exchanged with each other, it will have a profound impact on the germplasm improvement and innovation of lychee and longan.
So since the 1990s, scientists have begun to try the hybridization of lychee and longan, longan and lychee belong to the distant hybridization refers to the hybridization between species, between genera or more distantly related taxonomic units, can break through the restrictions of species and genera boundaries, produce rich genetic variation, but the difficulty is also very large, such as the moon season and pear are rose family, can you imagine the moon season on the pear?
Famous foreign agronomists such as McConchie have conducted intergeneration studies of lychee and longan, and compared the germination of pollen on the pistil stigma when lychee and longan were used as fathers. The results showed that lychee was used as the mother and longan as the father, and pollen could germinate and grow into the pistil ovary after pollination.
Crisp honey
With longan as the mother and lychee as the father, the pollen tube can rarely grow into the pistil chamber. In the end, 6 seedlings were obtained in the combination of lychee as mother and longan as father, and the genus true hybrids of lychee and longan were identified by isoenzymes.
But their experiments did not eventually form new varieties that could be cultivated for a long time, and the hybridization of longan and lychee was a worldwide problem, and Professor Liu Chengming of South China Agricultural University has been studying the hybridization of lychee and longan since 2007.
China has successfully achieved this
In 2007, the distant hybridization study was carried out with the lychee variety Zi Niangxi as the father, the longan varieties Shi Jiao, the precocious longan and Gushan No. 2 as the mother, and the Purple Niangxi as the mother and the stone kip longan as the father. The dissimilarity of intergeneration hybridization is improved by mixing pollination and multi-combination hybridization. The results showed that a total of 35 hybrid seedlings were obtained in the four hybrid combinations of Zi Niang Xi × Shi Jiao, Shi Jie × Zi Niang Xi, Precocious Longan × Zi Niang Xi and Gushan No. 2 × Zi Niang Xi.
How is this achieved? Professor Liu Chengming comprehensive use of physical, chemical and biological means, they camouflaged the pollen of the lychee, scientists before the blooming period, in the longan and lychee just opened on the male flowers, collect pollen, and then the pollen of the longan with ultraviolet lamp irradiation for more than 12 hours, so that it completely loses the ability to germinate, and then mixed with healthy lychee pollen, sent to the head of the longan column, then the longan stigma was confused by a chemical "secret recipe", and also thought that it was the longan, "deceived" longan, so successfully obtained hybrid seedlings.
After having hybrid seedlings, it is not so easy to breed a new variety, and in 2010, 69 intergenerational hybrid seedlings were colonized at the base of Huanong School. After several years of cultivation experiments, it was not until 2014 that the SZ52 hybrid strain was finally selected. From 2015 to 2017, the team conducted product ratio trials and regional trials. It was not until this year that "Crisp Honey (SZ52)" finally passed the on-site identification of new varieties. This means that "crisp honey (SZ52)" can already enter the mass production stage.
The crisp honey base in Shuixi Village, Conghua Aotou Town, can continue to pick until mid-September, which significantly extends the supply period of fresh fruits in longan, and the output can reach 4,000 to 5,000 kilograms, and with the further promotion of the future, the crisp honey sauce will enter the homes of ordinary people.
"Crisp honey" also has the characteristics of fresh flesh of lychee fruit, its fruit is nearly round, the skin is yellow-green, the fruit is larger, and the average single fruit weight is 11.5 g. Its flesh is thick, waxy yellow, edible rate of 70.8%, sugar content of up to 20-24%, eat the flesh is tender and crisp, completely slag-free, and the flavor is sweet and juicy, with aroma.
Moreover, as a late-maturing variety, the advantages of "crisp honey" hybridization make it have the characteristics of low temperature resistance and strong cold resistance, which makes it easier to achieve high yield and stable yield. In addition, "crisp honey" with its late ripening and cold resistance can make the longan production area move north, expand the production area, and extend the production period, and in the future, we can also eat fresh longan during the Mid-Autumn Festival.
The significance of "crisp honey" lies not only in the new breakthrough on the foodie's table, but also in that when everyone in the world says "impossible", there are Chinese scientists who dare to stand up and turn this "impossible" into reality.
Hybridized varieties have no effect on people
Then many people are very worried that such hybridization will not lead to mutations in fruit genes, changing the laws of nature, and thus harmful to the human body.
That is completely thinking too much, in fact, there are many natural hybridization phenomena in nature, such as the ordinary wheat we eat now, that is, natural hybridization, about 500,000 years ago, the wheat genus Of Uraltu wheat and goat grass plants pseudo-goat grass natural hybridization, forming a wild two grain of wheat; About 8,000 years ago, the cultivated two grains of wheat accidentally naturally crossed with another wild goat grass plant, and once again successfully broke through before reproductive isolation, and finally formed a heterologous hexaploid ordinary wheat.
The citrus family of the russet family is known for its chaos, with almost all species descendants of the three wild species of broad-skinned orange, grapefruit and citron. Almost any two species of this family can be hybridized when they touch each other, so that the hybrid offspring are a whole bunch: grapefruit and broad-skinned orange hybrids produce oranges, wide-skinned oranges and orange hybrids produce oranges, citron and lime or citrus hybrids produce various lemons, grapefruit and sweet orange hybrids produce grapefruit... In a series of hybrids, there is a law that citron is only a father, grapefruit is only a mother, and wide-skinned orange can be both a father and a mother.
Hybridization can give birth to more suitable dominant groups, which refer to a group of inbred taxa with rich genetic foundation, close co-ancestral relations, similar main characteristics and general coordination. The inbred lines within each heterozygous dominant group hybridize with each other without obvious heterosis, while the inbred lines hybridize between different heterozygous dominant groups may obtain a strong combination of dominant advantages. The hybridization method between two heterozygotic dominant groups that can obtain a strong dominant combination is called the heterosis utilization mode, referred to as the hybridization mode.
In fact, the grapes, apples, watermelons and other fruits we eat now are constantly selected and bred by agronomists, and their appearance in nature has long been very different, and it is precisely because of the existence of these agronomists that we can eat enough and eat well.