Citrus plants are believed to have originated in the southeastern hills of the Himalayas, including western Yunnan and other regions
Citrus decay disease caused by citrus tristeza virus (CTV) is one of the most serious diseases in citrus production.
On July 12, PLoS Pathogens published an online publication of the National Citrus Seedling Detoxification Center of the Citrus Research Institute of Southwest University, Zhou Changyong/Cao Mengji's team titled “Viromics unveils extraordinary genetic diversity of” on July 12 the family Closteroviridae in wild citrus" research paper
The thesis uses viromic research to reveal the diversity of longfilaviruses in wild citrus, and provides important information for further exploring the factors that promote the outbreak of citrus viruses and the evolutionary history of the longfilavirus family
Long linear virus may be native to Citrus
Long linear virus may be native to Citrus Zhou Changyong, the co-corresponding author of the paper, told China Science Daily that the word tristeza in the scientific name of citrus decay virus means sadness or melancholy in Portuguese, which means that many citrus plants appear after being grafted onto rootstocks such as limes or lemons.
Citrus decay virus (CTV) causes symptoms such as decay, stem sinking, and fruit shrinkage
Citrus decay virus (CTV) causes symptoms such as decay, stem sinking, and fruit shrinkage
Cao Mengji, the co-corresponding author of the paper, said in an interview with "China Science News" that they collected wild citrus in the Ailao Mountain region of Yunnan Province, which is the center of the origin of citrus species, and discovered four long-line shapes using macroviromics methods.
"Only long-filament viruses have been found in wild citrus, which indicates that citrus decay virus and other citrus long-filament viruses may be native to citrus plants and co-evolve with the citrus host, while other viruses that infect citrus may be derived from Other plants are transferred to cultivated citrus
Long linear virus identified in wild citrus
Long linear virus identified in wild citrus
The diversity of long-line viruses far exceeds cognition
The diversity of long-line viruses far exceeds cognition Cao Mengji said that in the long co-evolution process, these long-line viruses coexist with fungi, bacteria and other parasites in the plant host, allowing the viruses to recruit genes from different sources through horizontal gene transfer
Frequent horizontal gene transfer, gene duplication and recombination have driven the evolution of long-line viruses
Frequent horizontal gene transfer, gene duplication and recombination have driven the evolution of long-line viruses
Liu Qiyan, the co-first author of the paper and a master's degree student in the Detoxification Center of the Citrus Institute of Southwest University, said that the newly identified viruses show that the diversity of the long-line virus family far exceeds previous recognition
They identified three horizontally transferred genes from the clonal viruses that infect citrus and other plants, that is, foreign genes, which code for thaumatin, metal ion transporter and 3-5 exonuclease, respectively
.
Among them, thaumatin is related to crop resistance to fungi and adversity, and 3-5 exonuclease is the only case of RNA virus encoding exonuclease other than coronavirus
.
Frequent horizontal gene transfers in the Longfilavirus family
.
Photo courtesy of Citrus Institute, Southwest University
Frequent horizontal gene transfers in the Longfilavirus family
.
Photo courtesy of Citrus Institute, Southwest University Cao Mengji emphasized that horizontal gene transfer and gene duplication are closely related to the formation of the size and complexity of the genomes of the members of the Feroviridae family, and subsequent co-differentiation and cross-species transmission events may have produced other different genes of the Feroviridae.
.
Long-term monitoring of long-term virus
Long-term monitoring of long-term virus Zhang Song, the co-first author of the paper and a PhD student in the Detoxification Center of the Citrus Research Institute of Southwest University, introduced that the grafting test showed that one of the new viruses exhibited leaf-rolling-related symptoms on different citrus varieties, while the other citrus had long lines.
Symptoms and epidemic risks of Xingxin virus remain to be explored
.
Analysis of biological symptoms of citrus infected by CaAV-1 alone
.
Photo courtesy of Citrus Institute, Southwest University
Analysis of biological symptoms of citrus infected by CaAV-1 alone
.
Photo courtesy of Citrus Institute, Southwest University "As one of the origins of citrus, our country contains quite a wealth of viruses.
Our work suggests the importance of the protection of wild citrus resources
.
Some viruses have co-evolved with citrus hosts for a long time.
In order to survive, they will not be in the original host.
It produces very serious symptoms
.
Once they become popular in cultivated citrus and spread to different citrus varieties, they may have a devastating blow to the citrus industry
.
" Zhou Changyong said
.
Especially under the large-scale monoculture planting mode of modern crops, plants are more susceptible to various pathogens, and the globalization of trade will promote their spread to new regions
.
Therefore, Zhou Changyong suggested that it is necessary to study the biological characteristics of these long-line viruses on different citrus varieties such as symptoms and transmission methods, and to monitor their pathogenicity and epidemiological characteristics, and to control their possible transmission channels
.
It is a virus and can also be used to control citrus diseases
It is a virus and can also be used to control citrus diseases Cao Mengji told the China Science Daily that viruses are a double-edged sword.
As pathogens, they may cause the yield loss of various agricultural crops
.
However, from a beneficial point of view, some RNA interference vectors derived from filamentous viruses can be used for plant disease control
.
RNA interference, also known as post-transcriptional gene silencing, refers to the introduction of specific homologous double-stranded RNA into the cell so that the target gene is not expressed or the expression level is reduced
.
Citrus psyllids are the main spreaders of citrus yellow dragon disease
.
In 2014, scientists developed an RNA interference vector based on the citrus decay virus, and expressed genes that induce citrus psyllid wing abnormalities in citrus plants
.
It can be used as a temporary solution to reduce the spread of citrus yellow dragon disease in the field
.
"The new citrus long-line virus discovered this time also has a large genome, which can be used to construct a new vector suitable for citrus trees, thereby becoming a tool for citrus protection and improvement
.
" Cao Mengji said, because it is made by citrus native virus.
The modified carrier will have better specificity and adaptability on the citrus host
.
Secondly, the larger genome of the filamentous virus can accommodate larger exogenous genes, such as genes related to plant stress resistance and disease resistance, and provides heritability and stability that other plant virus vectors cannot match
.
It is reported that several filamentous viruses have been developed as vectors for several economical woody plants, and the newly discovered filamentous viruses have good potential as vectors for citrus disease control and character improvement
.
The research is mainly funded by projects such as the National Key Research and Development Program, the National Natural Science Foundation of China, and the special funds for basic scientific research operations of central universities
.
(Source: China Science News Li Chen)
Related paper information: https:// doi.
org/10.
1371/journal.
ppat.
1009751
https:// doi.
org/10.
1371/journal.
ppat.
1009751 https:// doi.
org/10.
1371/journal.
ppat.
1009751
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