The study reveals a new mechanism of rape growth and immune dynamic regulation.

Original title:
Study Reveals New Mechanisms for Rapeseed Growth and Immune Dynamic Regulation
On November 30, Molecular Plant magazine published online the Guo Huishan Task Force of the Institute of Microbiology of the Chinese Academy of Sciences and the Center for Excellence in Molecular Plant Science and Innovation of the Chinese Academy of Sciences/Shanghai Plant Physiology and Ecology Research Center A research paper, entitled A Brassica miRNA Regulation Plant Growth and Immunity Through Distinct Modes of Action, was co-authored by the Duancheng National Task Force, which reported on a 22 nt miRNA found in rape that dynamically regulates rape resistance and development through different mechanisms.
Plants, faced with adversity such as pests and diseases, tend to consume more metabolic resources at the expense of inhibiting normal growth and using more metabolic resources for the activation of defense systems to resist pathogen invasion, a phenomenon known as "tradeoff". Therefore, in crop breeding, how to coordinate the balance of growth and resistance becomes a major challenge.
In plant
immune
mechanisms, the immune-perceptor R protein identifies pathogenic effect protein-induced immune responses and small molecule RNA-mediated RNA silencing , including antiviral RNA silencing and cross-border RNAi-mediated antifactoxic mechanisms, are two important defenses.
if there is no pathogen infection, the continued high expression of R protein can induce the occurrence of autoimmunity, resulting in severe inhibition of plant development. Therefore, there is a reverse regulation mechanism in plants that controls the expression of the R gene. Among them, miRNA-mediated RNA silencing can control the expression level of the R gene at the level after transcription and play an important role in plant autoimmune regulation. MiRNA is also important for regulating plant growth and development. So, is there miRNAs in plants that regulate both growth and development and immune resistance? If the infection of pathogens can be answered, the study of its molecular mechanism will have very important guiding significance and application value to the "growth and defense trade-off" of crop breeding.
Rape belongs to the crusader genus, known in ancient China as "yu", is a kind of adaptable, wide-ranging, high economic value, cultivation of a long history of oil crops, the world's oil crop production is second only to soybeans. Canola is also an important oil crop and cash crop in China, and in agricultural production, the virus is an important pathogen that seriously harms rape production, such as the tern leaves virus (TuMV).
the study found that a 22 nt miRNA-miR1885 specific to rape can target the TIR-NBS-LRR type R gene BraTNL1, improve bratNL1 expression levels to enhance rape resistance to TuMV. The results show that under non-intrusive conditions, miR1885 mediated the shearing of BraTNL1 to maintain the immune activity of the background level.
addition, miR1885 targets a BraTIR1 gene with only a TIR domain, miR1885 mediated BraTIR1 shearing and producing a series of arranged secondary siRNAs (phasiRNAs), one of which is phasiRNA-phasi R130-4, which targets braCP24, a gene associated with silencing and photochips, suggests that BraTIR1 is involved in cauliflower flowering regulation as a TRANS-Acting gene, i.e. reducing BraCP24 to promote cauliflower transition.
Interestingly, the researchers found that the accumulation of miR1885 changed dynamically with different stages of development, maintaining low levels during the seedling period, peaking in flowering, and rapidly dropping to very low levels after flowering, reflecting the fact that the seedling period of plants passed through miR during the uninfested period. The 1885/BraTNL1 module maintains immune activity at this background level while inhibiting premature flowering of plants and promoting nutritional growth through the miR1885/BraTIR1 (phasiR130-4)/BraCP24 module.
researchers also found that TuMV infestion induced miR1885, through phasiR130-4 mediated BraCP24 degradation to promote flowering; Consistent with this, over-expression miR1885 leads to an early flowering period and smaller fruit pods, while rapes with lower miR1885 show developmental esoteric patterns such as late flowering and fruit pods getting bigger.
this study reveals for the first time that plant miRNAs target both immune subject R genes and development-related genes through different mechanisms, dynamically regulating plant immunity and development, and responding to pathogen invasion. It reflects an integrated coping strategy adopted by plants in the face of the interaction between normal growth, immune mechanism and pathogen infection.
Duan Chengguo and Guo Huishan are co-authors of the paper, as well as Dr. Cui Chen, Wang Jingjing and Zhao Jianhua, associate researchers at the Institute of Microbiology. The research was supported by the Pilot B Project of the Chinese Academy of Sciences and the National Natural Science Foundation of China.
1. miR1885 dynamically regulates the growth and development and immunity of rapeseed. A. The growth and development esophost of kale-type rape expressed by miR1885. The picture on the left shows the whole rape plant 60 days after germination, the middle picture shows the fruit (top) and flowers (bottom) of rapeseed, and the right image shows the rape leaves 40 days after germination. B. Expression of small RNA and target genes in rape leaves and cauliflower at different growth times. C.miR1885, phasiR130-4 and its target gene expression patterns in rape at different growth times. Blue lines represent expression trends for miR1885 and phasiR130-4, and red lines represent expression trends for the target gene BraTIR1, BraTNL1, BraCP24.2. miR1885 regulates the growth and immunity of rape in different ways. A. In the state of natural growth, miR1885 and the resulting phasiR130-4 background horizontal expression, maintain the basic resistance of the rape disease-resistant gene, and ensure the expression of the photodetexual gene BraCP24. B. TuMV infestion promotes the production of miR1885, phasiR130-4, while improving the expression of rape disease-resistant genes, resulting in the expression of photosynthemum-related gene BraCP24 is inhibited, prompting the development of rape abnormalities, early flowering.
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