How to make "golden fiber"

Photo courtesy ofJuteZhang Liwu

As one of the most important long-fiber crops in the world, jute is second only to cotton in terms of production and planting area in the world.
It enjoys the name of "golden fiber" and plays an important role in the flax industry
.

On June 25th, Fujian Agriculture and Forestry University's Bast Fiber Research Center and the University's Genomics and Biotechnology Center published the first chromosome-level jute reference genome map in Plant Biotechnology Journal
.

First to publish the jute genome at the chromosome level

Jute, also called hemp and green hemp, is an annual herbaceous bast fiber crop
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According to data from the United Nations Food and Agriculture Organization, the current global annual output of jute fiber is 3,422,876 tons, with an output value of 2.
3 billion US dollars
.

In recent years, textile technology has made great progress jute, jute fiber spinning pure or blended been able to grade fabric, or woven into Qiangbu, tablecloths, curtains and other decorative fabrics
.

Zhang Lilan, the first author of the thesis and a doctoral student at Fujian Agriculture and Forestry University, introduced that they used the round fruit jute fine variety "Jute 179" and the long fruit jute fine variety "Wide Leaf Longguo" as materials, and adopted the second and third generation sequencing strategies.
At the same time, combined with Hi-C chromosome conformation capture technology, the jute chromosome-level whole-genome sequencing and assembly work was completed for the first time
.

The genome sizes of the round-fruited jute and the long-fruited jute obtained in this study were about 336 Mbp and 361 Mbp, respectively, and the contig N50 was 46 Mb and 50 Mb, respectively, and 25874 and 28479 protein-coding genes were identified, respectively
.

Since both jute and Raymond's cotton belong to the Malvaceae family and are both diploid fiber crops, they also compared the formation time of the two species
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Although the round-fruited jute and the long-fruited jute showed good collinearity, the long-fruited jute genome was 25 Mbp longer than that of the round-fruited jute, and contained 13 putative inversions
.

The origin and domestication of jute

In order to analyze the origin and domestication of jute at the genomic level, they re-sequenced 242 pieces of round fruit species of jute, 57 copies of long fruit species of jute, and 1 copy of a related species of pseudo jute from all over the world, and a total of 300 different jute genus materials.

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Population bottleneck, also known as "population bottleneck effect" or "population bottleneck", refers to an event in which the number of a certain population is reduced by more than 50% or orders of magnitude due to death or infertility during the evolution process
.

The first author of the paper, Dr.
Ma Xiaokai from Fujian Agriculture and Forestry University, said that after the population bottleneck occurs, it may cause the extinction of the population or the restoration of the population but only limited genetic diversity remains
.
In the study of population size changes in history, jute genome sequencing data can be used to analyze the effective population size of population history by using classic genetic algorithms
.
Jute bottlenecks began to appear 20,000 years ago
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The population size continued to decline, indicating that the jute population was subject to greater natural or artificial selection at this time
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The author of the paper, Professor Ray Ming of the University of Illinois at Urbana-Champaign, said that during the Last Glacial Maximum (LGM), the round fruit species of jute only existed in southern Asia, while the long fruit species of jute existed in eastern Africa and southern Asia
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As time goes by, the distribution of jute in Africa is less and less, and more and more in Asia
.
It provides a basis for proving that the long-fruited jute originated in eastern Africa and experienced the second domestication in eastern Asia
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Xu Yi, the first author of the paper and a doctoral student at Fujian Agriculture and Forestry University, explained that jute is an annual short-day crop that likes a warm and humid climate
.
As temperatures in Africa increase and droughts intensify, while Asia has suitable temperatures and abundant rainfall, African jute resources are becoming increasingly scarce, and Asia has turned to become a major producer of jute
.
"The distribution of jute is affected by climate change, human cultural exchanges and artificial selection in Asia and Africa
.
"

Discovery of important genetic loci of jute fiber quality

"Because jute is a phloem fiber crop, its most important economic product is phloem fiber, so we hope to
discover important genes related to the formation of phloem fiber, which can provide a theoretical basis and genetic resources for the improvement of jute fiber .
" Zhang Liwu said
.

They used transcriptome sequencing technology to unearth genes related to fiber formation in the phloem of jute, including genes involved in the regulation of lignin and cellulose synthesis pathways, as well as regulatory genes that affect the initial elongation of fibers, and mapped the expression profiles of these genes
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Genome-wide association analysis GWAS analysis, they identified hundreds of important sites for fiber quality traits that control fiber fineness, cellulose content, and lignin content
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Combined with selective clearance analysis, it is found that the candidate genes of the microfilament family protein CcSFP1 and protein arginine methyltransferase CcPRMT7 of the fiber fineness QTL are located in the selective clearance region.
It is speculated that these genes have been domesticated and selected
.
The function of candidate genes CcCOBRA1 and CcC4H1, which control the quality of jute fiber, was verified by competitive allele-specific PCR (KASP) and transgenic technology
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The COBRA gene can control the correct position of cellulose microfibrils in the cell wall and the directed elongation of plant cells
.
In rice, mutations in the COBRA gene can reduce cell wall thickness and cellulose content, and have the function of regulating the mechanical strength of rice stalks, which are called "fragile stem genes"
.
In jute, they found that the expression level of CcCOBRA1 increased with fiber development, indicating that this gene is an important site that controls the quality of jute fiber and affects fiber accumulation
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The C4H gene mediates the conversion of cinnamic acid to p-coumaric acid, and is one of the most important genes regulating plant lignin synthesis.
Its transcription abundance can directly affect the biosynthesis of flavonoids and aromatic compounds in plants
.
The mining of these genes provides genetic resources for the genetic improvement of jute fiber quality
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Su Jianguang, a researcher at the Bast Research Institute of the Chinese Academy of Agricultural Sciences, said that the research results were the first to complete the accurate sequencing of jute chromosomes and gene structure analysis, and carried out the whole genome association analysis of jute complex traits based on whole-genome sequencing analysis, and analyzed the key inheritance of jute fiber quality.
Sites, systematically identified jute genome-wide domestication selection sites, which proved that the long-fruited jute species originated in eastern Africa and experienced a second domestication in eastern Asia, solving the mystery of jute domestication and origin, and is a functional gene of jute Validation and molecular design breeding provide means
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It is understood that the deciphering of the whole genomes of two cultivars of jute for the first time in the world indicates that China is at the international leading level in the research of hemp crop genomes and molecular breeding
.

Related paper information: https://doi.
org/10.
1111/pbi.
13652