The Role Of Rice GRAS Transcription Factor RAD1 To Regulate Mycorrhizal Symbiosis

In the natural environment,more than 80%of plants can form a mutually beneficial symbiotic relationship with arbuscular mycorrhizal fungi(AMF).In this symbiotic relationship,fungi can effectively help plants to absorb and utilize nutrients such as phosphorus and nitrogen in soil to promote the growth and development of plants.On the other hand,plants transmit photosynthetic products to the fungus for growth in the form of carbon.The symbiosis between plants and AMF involves the identification and transmission of a series of signaling molecules,which are finely regulated by plants and fungi.The signal molecules released by plants are perceived by the fungus and induce AM fungus germination,branching and secretion of mycorrhizal factors.The mycorrhizal factors can be identified by the receptors on the cytoplasmic membrane of the plant.,and then open the cation channels on the nuclear membrane,cause the oscillation of the calcium ion in the nuclei,calcium oscillation signal is identified and transmitted and the transcription factors activate the expression of downstream genes,regulate the symbiosis of plant and AMF.In AM symbiosis signaling pathways,GRAS family of transcription factors RADI played an important role in regulation,but its evolution pattern and mechanism of action remains to be further research,this article preliminarily explored transcription factors RADI involved in regulating the function of the rice AM symbiosis.In this study,we first analyzed the evolution of five representative terrestrial plants and constructed the phylogenetic tree of the GRAS gene family,and found that it had nearly thirty branches in angiosperms.The RAD1 gene belongs to one of the branches,and the evolution is very conservative.There are two copies of Oryza sativa and Single copy in Amborella trichopoda.Medicago truncatula and Solanum lycopersicum.Secondly,one copy of RADI gene in rice was found to be induced by AM symbiosis through qPCR,indicating that this gene is likely to participate in the AM symbiosis process.In addition,the expression location of OsRAD1 gene induced expression is related to the symbiosis structure through the staining of GUS in rice,further indicating that the OsRAD1 gene is likely to participate in the regulation of AM symbiosis.To explore whether RADI in non-leguminous plants participated in AM symbiosis.We silenced the SIRAD1 gene in tomato through VIGS,it was found that the transcription level of AM symbiosis marker gene was reduced,and the development arbuscular was affected,the result explain that SIRAD1involved in regulation of tomato arbuscular mycorrhizal symbiosis.Therefore,we used CRISPR/Cas9 to knock out the OsRAD1 gene in rice,and then study the regulatory role of OsRAD1 in the symbiotic signal transduction pathway of arbuscular mycorrhizal symbiosis.We found that the development of arbuscular in the osrad1 mutant was blocked,and fungal infection rate?infection intensity and arbuscular abundance were all lower than wild-type,as well as the transcription level of AM symbiosis marker genes OsPT11?OsAM1 and OsAM3 dropped significantly.The results of this study show that RAD1 gene is conservative in different species,and its function is very conservative,and plays an important regulatory role in the signaling pathway of plant and arbuscular my corrhizal fungi symbiosis.