From the "China" crop, liquid gold will be synthesized from rape

natural substance Hohoba oil is a popular cosmetic raw material. However, few people know that Jojoba's Latin name is "China". In fact, in the 1970s, our country began to breed Hohoba sporadicly, with little scale. The named yin and yang error stems from the confusion between the Hohoba seeds collected by early 19th-century discoverers from a botanical garden in the United States and another in China.
, however, Hojoba's historical link with China could be rewritten by Chinese scientists.
Recently, Science-Progress published online the high-quality reference genome of Hohoba, an oil crop, which was jointly completed by the rape team of Huahua Agricultural University and five units outside the United Nations, and analyzed the wax ester synthesis pathway in Hohoba seeds. Scientists believe it will no longer be a dream to synthesize Hohoba oil from oil crops such as rape in the south of the country.high-quality Hohoba oil costs $58 per kilogram, there are no other natural alternatives, there is no efficient synthesis method, but global production is 50 times different from the expected demand, so Hohoba oil is called "liquid gold."
oil, which is native to the American desert, is very special and is actually a liquid wax ester. Guo Liang, the paper's author and a professor at Hua zhong Nong University, told the China Science Daily that the liquid wax is made up of fatty alcohols and fatty acids with a carbon chain length of C20-C24, which are unique in the plant kingdom;
" Hohoba is the only oil plant known to synthesize liquid wax esters. Guo Liang introduced that the all-natural Hohoba oil has strong antioxidant, permeability characteristics, its structure is similar to human sebum, easy to be absorbed by the skin, not greasy, and can promote the retention of skin moisture.
Previous studies have shown that the composition of Hohoba oil will not change significantly with factors such as planting site, soil type, rainfall or altitude, long-term preservation after harvest is not easy to change, high temperature, high pressure stability is very good, is widely used in such as mechanical lubrication, de-foaming, anti-wear, rust and anti-oxidation and so on.
, however, due to the complex synthesis process, harsh conditions, low yield, especially the ultra-long chain fatty alcohol synthesis costs are extremely high, there is no synthetic Hohoba oil products.
Hohoba, originally known as the "magic shrub", has also been hailed as "the gospel of saving arid areas". Studies have shown that older Hohoba trees can survive even if it doesn't rain for a year in the desert. In general, hohoba trees have a lifespan of about 200 years. Although Hohobamu is highly resistant to heat and drought, its seedlings do not like drought, and it is difficult to ensure the survival rate of afforestation without artificial irrigation in the early stages of afforestation.
Xinwei, a researcher at the Institute of Forelinization of the Chinese Academy of Forecology, has written that Hohobamu is naturally distributed in the Sonora Desert region of North America. It has been commercially grown in the United States, Israel, Peru, Argentina, Australia and India. It is estimated that when 2.833 million hectares are planted worldwide, Hohoba oil will initially meet current consumer demand.
1971, after the International Whaling Commission issued a whaling ban, Hohoba oil received a high degree of attention. Guo Liang told reporters that due to the long growth cycle of Hohoba wood, female plants only account for about 20% of the natural population, and high-quality Hohoba oil generally comes from desert areas, resulting in the development of the Hohoba wood industry is relatively slow. In addition, the conventional mechanical press oil extraction rate is not high also has a certain impact on its industry.
", while global production of Hohoba oil rose from 500 tonnes in 1986 to 4,000 tonnes in 2012, there is a huge gap with the expected annual consumption of about 200,000 tonnes of Hohoba oil. As a result, the oversupply of Hohoba oil and its commercial and industrial value have led to high prices. Guo Liang said.
our country began to plant Hohoba wood in the late 1970s until the basic end of the introduction in the 1990s. However, this oil crop, called "China", has not been studied for good seed selection in China, and the asexual breeding and insertion technology has not been completely broken, and has not yet produced economic benefits.Over the past decade or so, scientists have genetically engineered the synthesis of Hohoba wax esters in the seeds of oil crops such as rapeseed and linen mustard, which accumulate low levels of wax esters and have low seed germination rates. In Hohoba's seeds, wax fat accounts for more than 95% of the total oil content, and the seeds can still germinate normally, suggesting that there are special mechanisms for the synthesis, storage and degradation of wax esters in Hohoba seeds.
t get a high-quality reference genome at chromosome level, and the world's first Hohoba genome map," he said. Guo Liang told China Science daily that previously, the lack of reference genomes had limited the analysis of the mechanisms associated with wax ester synthesis in Hohoba seeds.Using a combination of PacBio, Illumina and Hi-C sequencing, they assembled the Hohoba reference genome with a genome size of 887 Mb and a Contig N50 size of 5.2 Mb, annotated the genes of 23,490 encoded proteins, said Chen Lingling, co-author of the paper.
, the team began to analyze the wax ester synthesis mechanism.
Chen Lingling, the content of wax esters in Hohoba seeds is about 50% of the seed's dry weight, providing energy and carbon sources for seed germination. The synthesis of wax ester is mainly through lipidase A reductase FAR to reduce lipid coenzyme A to fat alcohol. Then, under the role of wax ester synthase WS, fatty alcohol and lipid coenzyme A ester reaction to produce wax ester.
many microorganisms, such as immobile bacteria, eye worm algae and deep-sea algae, can also be synthesized in cells wax lipids. But "the length of the carbon chain of Hohoba wax esters is different from theirs, and its function is not the same." This may be due to differences in the substrate preferences of FAR and WS in each species. Guo Liang told China Science Daily.
they analyzed the distribution of lipids in Hohoba seeds and found that wax esters were mainly found in the sub-leaves of the seeds, while very little triglycerides were mainly found in the seed's embryo shaft. Transcription group analysis at different sites of the seed showed that the expression of the associated gene adipase-CoA extensionase 1 gene (ScFAE1), fatty acid reductase gene (ScFAR) and wax ester synthase gene (ScWS) in the sublatery was much higher than that in the embryo shaft. At the same time, the expression of diglyclyglycryl-based transferase (DGAT) in the sub-leaf is much lower than its expression in the embryo shaft. " encoded fatty acid synthesis and fat storage-related proteins are biased toward high expression in the sub-leaf. Differences in the spatial expression of these genes may be the main reason for the significant distribution of wax esters and triglycerides in Hohoba seeds. Chen Lingling said.
"these studies provide us with an in-depth understanding of the mechanism of hohoba wax ester synthesis, providing a theoretical basis for the improvement of the Hohoba variety." Cui Peng, a researcher at the Agricultural Genome Institute of the Chinese Academy of Agricultural Sciences, told the China Science Daily. the high price of Hohoba oil severely limits its use, but is only used in some drugs, cosmetics. Guo Liang said that at present, a large number of wax esters on the market demand is mainly obtained through chemical synthesis or lipase-based biotechnology. However, these fatty alcohols must be chemically synthesized to obtain, resulting in high costs.
, "the need to produce cheap Hohoba-like paraffins is becoming increasingly urgent." Guo Liang explained that the use of genetic engineering and metabolic engineering in organisms to synthesize a large number of Hohoba oil-like wax esters became the first choice.
scientists have used athropomorphic mustard and flaxseeds to synthesize wax esters similar to Hohoba oil under laboratory conditions. But none of their offspring's seed germination success rates were ideal.
, as the largest vegetable oil production crop in China, has accumulated abundant species resources since the introduction of domestication in the middle of last century. With the change of planting mode and rural labor force structure and the influence of rapeseed oil economic benefits, the benefits of rape cultivation industry in China are decreasing year by year.
Guo Liang believes that the composition of fatty acids in high mustard rape seeds is in line with the background preferences of FAR and WS in Hohoba, which makes it possible to synthesize Hohoba oil in high mustard rape seeds. The large amount of synthetic hohoba oil in rape seeds will not only reduce the cost of hohoba oil on the market today, but also improve the efficiency of rape cultivation. the advent of high-quality genomes and the unveiling of wax synthesis mechanisms will help scientists solve some of the key scientific problems of synthesized wax esters in rape seeds.
addition, Cui Peng believes that the biggest problem facing hohoba planting at present is the difference between male and female plants, the proportion of female and male plants (1:4). Due to the low proportion of female plants, the low input-output ratio of growers has severely limited the development of the Hohoba planting industry, and the publication of the Hohoba genome sequence provides the basis for solving the problem of female strain screening.
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