Mustard plants and leaves and seeds
Mustard plants and leaves and seeds
For nearly a century, the origin and domestication of mustard has been an unsolved scientific controversy
On September 6, "Nature-Genetics" published online the latest results of cooperation between the teams of Hunan Agricultural University and the Oil Crop Research Institute of the Chinese Academy of Agricultural Sciences, which clarified the genetic basis of the mustard population structure and diversity variation, and revealed the origins and origins of mustard.
Unsolved case unsolved for a hundred years
Unsolved case unsolved for a hundred years Cultivation refers to the cruciferous crops that harvest seeds and extract oil as rape, including cabbage-type rape, mustard-type rape, and cabbage-type rape
Liu Zhongsong, the corresponding author of the paper and a professor at Hunan Agricultural University, told the China Science Journal that allotetraploid mustard has 36 chromosomes and is a natural hybrid between cabbage (20 chromosomes) and black mustard (16 chromosomes) grown by diploid ancestors.
Mustard has a long history of cultivation and domestication.
"It is generally believed that mustard green originated in Asia
Mustard greens located in Tibet, China
Mustard greens located in Tibet, China
"Therefore, more comprehensive research is needed to reveal the mystery of mustard's life experience, and it will also help to carry out the follow-up work of mustard breeding and improvement
Single origin + three independent paths of domestication
Single origin + three independent paths of domestication The study used a number of genetics and genomics sequencing technologies to assemble the mustard-type rapeseed Sichuan yellow seed genome from scratch, and finally obtained a highly accurate chromosome-level genome map, which is superior to the previously published Chinese stem mustard and India in all aspects.
“In order to explore the genetic variation of mustard, we re-sequenced 480 germplasm materials from 38 countries around the world, including 4 subspecies
Further research clarified the genetic relationship within the mustard population, showing three branches and 6 genetic groups corresponding to different forms, namely the root mustard population on the first branch, and the 4 seed mustard populations on the second branch.
"To study the evolution of species, we have to draw an evolutionary tree, like a big tree with a trunk, branches and branches, so that the tree-like branch graph can be used to express the relationship between species and different types of species
In order to clarify the domestication and spread of mustard, they constructed a subgenomic phylogenetic tree of mustard and its ancestors, and assembled 478 chloroplasts and 10 mitochondrial genomes at the same time to study the cytoplasmic relationship between mustard and its ancestors
.
Hua Wei said, first, the mustard evolutionary tree has only one main stem, and then evolved different branches, indicating that mustard produced 6 different populations from one ancestor; secondly, the cytoplasmic genetic material, including chloroplast and mitochondrial DNA, showed maternal inheritance.
Cytoplasmic traceability revealed that mustard has only one "mother"
.
"We have confirmed from these two aspects that mustard is of single origin
.
"
Later, combined with archaeological evidence and historical written records, they found that mustard originated in West Asia 8000 to 14000 years ago.
During its spread from west to east, three independent transmission paths were formed, and six were evolved through genetic mutation and introgression and hybridization.
Genetic group
.
"Three transmission routes correspond to three evolutionary branches and three independent domestication events.
Mustard is domesticated separately on each transmission route.
This is the result of regional environmental adaptation and human selection
.
" Liu Zhongsong said, genomics and evolutionary research pointed out.
mustard order domestication occurred, estimated the approximate time of domestication, consistent with the results of archaeological excavations and historical records of previous literature should relations, reveals the process of mustard spread from west to east
.
Correspondence, revealing the process of mustard spread from west to east
.
"Although there are no wild species in our analysis materials, the literature data shows that there are wild species distribution in West Asia (Middle East)
.
" Hua Wei said, hoping that West Asia can restore a peaceful and tranquil environment as soon as possible, and allow scientists to collect germplasm resources and possibilities in the region .
The wild species further reveals the life experience of mustard
.
The Source of Variety of Mustard Form
The Source of Variety of Mustard Form "Species" is the basic unit of biological classification, which refers to a group of organisms with a certain natural distribution area and certain morphological and physiological characteristics
.
Individuals in the same species have the same genetic traits, and mating with each other can produce fertile offspring
.
The "subspecies" is generally considered to be a group within a species, with some variation in morphology, and isolation in terms of geographic distribution, ecology or seasons
.
"Mustard greens have undergone major changes due to domestication and artificial selection, which are mainly manifested in the increase in seed size, root enlargement and stem enlargement
.
Mustard greens therefore form four subspecies
.
" Kang Lei said, the morphology of mustard greens is very diverse.
, The size and shape of the leaves are very different, some rhizomes are enlarged and elongated; while some have small grains, 1000 mustard seeds may be less than 1 gram, but there are also large grains, which weigh 7 to 8 grams
.
Subsequently, they conducted a more detailed study on these domesticated traits
.
The study identified 22 candidate genes that are significantly related to 1000-seed weight, and 7 genes can also be detected by selection and elimination
.
Selecting these genes that adapt to the local photoperiod can induce changes in the size of mustard seeds
.
They compared the root mustard genome with that of seed mustard and leaf mustard and identified 14 candidate genes related to storage root formation, which may play a role in auxin signaling, sugar transport, cell division, cell expansion, and cell wall modification
.
The characteristic of stem mustard is that the stem is thick, and the diameter of the edible stem is greater than 20 cm, which is much larger than that of leaf mustard
.
After comparing the stem and leaf mustard genomes, they identified a total of 5,018 related genomic regions
.
"By comparing different types of mustard, such as large-grain materials and small-grain materials, rhizome expansion materials and non-swelling materials, we analyzed and looked at the genomic traces left by different materials in the evolution process, and found seed mustard, root mustard and stem mustard.
Unique genomic region
.
" Kang Lei said, further identifying a series of candidate genes, analyzing the tissue expression specificity of these candidate genes, and seeing whether they are expressed in different morphological tissues, the expression period and the level of expression, so as to determine which genes Related to morphology
.
Liu Zhongsong said that this paper resolved the century-old dispute over the origin of mustard, revealed the source of the variety of mustard morphology, provided a guide for the collection and utilization of mustard germplasm resources, and established a road map for mustard genomics research, making it possible to find new The gene becomes simpler and more convenient
.
The new genes and haplotypes that have been identified provide scientific basis, genetic resources and selection methods for genomic selection and breeding of mustard for different purposes, which will help improve breeding efficiency and accelerate the process of mustard breeding
.
(Source: China Science News Li Chen)
Related paper information: https://doi.
org/10.
1038/s41588-021-00922-y
https://doi.
org/10.
1038/s41588-021-00922-y
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