Functional Analysis Of Rice Transcription Factor OsDERF8 Regulating Leaf Senescence

Rice(Oryza sativa)is one of the major food crops in the world.Increasing rice production is crucial to cope with the growing demand for food.So far,a large number of green maintaining mutants have been found in model plants,and the emergence of functional green extending phenotype is one of the breakthrough points for increasing yield and increasing efficiency.Many physiological changes occur when plants respond to stress.Plant hormones play an important role in regulating plant growth and stress response.Jasmonic acid(JA)is an endogenous growth regulator in higher plants and a well-known inducer of aging.Senescence process is activated or inhibited by related transcription factors.AP2/ERF,as one of the plant-specific transcription factor family,is involved in many different stress processes during plant life cycle,and its research functions mainly focus on abiotic stress response.Little research has been done on how ERF-like transcription factors improve crop yields.In the early stage of this study,in order to explore the molecular mechanism of response to jasmonic acid signal,OsDERF8 transcription factor was screened by reference to other transcriptome data analysis,OsDERF8 was cloned and rice genetic materials were constructed,and the function of OsDERF8 was explored through dark induced aging and natural aging.OsDERF8 affects leaf senescence process.And the related molecular mechanism is analyzed.The results are as follows:1.The expression patterns of transcription factor OsDERF8 under different treatments were analyzed by q RT-PCR.Bioinformatics analysis showed that OsDERF8 transcription factor was closely related to OsERF101 in rice and come together in a cluster,and it was reported to be involved in JA-mediated leaf senescence process.Amino acid sequence analysis showed that the AP2 domain was conserved as ERF family genes.Transcription factor OsDERF8 was located in the nucleus by subcellular mapping of rice protoplasts.2.The stable overexpression lines of OsDERF8(OsDERF8-OE)and CRISPRCas9 knockout lines(Osderf8-ko)of rice variety ZH11 were constructed and screened to homozygote.In the dark treatment at seedling stage,the experiment result shows that,OsDERF8 overexpressed leaves yellowed early,and Osderf8 mutant leaves yellowed later than ZH11.Osderf8 mutant had higher chlorophyll content and more complete chloroplast structure.In natural environment aging,OsDERF8 overexpression showed poor growth phenotype,shortened growth period and decreased yield.But the leaf photosynthetic time of Osderf8 mutant was prolonged,the grain was full and the yield was increased.3.By RNA-Seq analysis,chlorophyll degradation and senescence related genes were significantly decreased in Osderf8 mutant,which was a negative regulator of senescence.The expression of photosynthetic related genes in Osderf8 was significantly up-regulated,indicating that Osderf8 maintained higher chlorophyll content and photosynthetic capacity.Hormone-related genes were also highly enriched,especially JA signaling and synthetic genes.Transcriptome data were verified by q RT-PCR.Promoter-luc experiments confirmed that OsDERF8 can activate Promoter regions of senescence marker genes(OsNAP,Osl85)and chlorophyll degrading genes(OsNYC1,OsPAO),suggesting that OsDERF8 may regulate leaf senescence by regulating transcription levels of these genes.4.Transcription factor OsDERF8 affected the plant type and root development of rice.Compared with ZH11,the root system of Osderf8 mutant was developed,and the root system of OsDERF8 overexpression was inhibited.OsDERF8 overexpression increased the leaf Angle during reproductive development.In addition to JA signals,various hormones may be involved in the above processes,such as the enrichment of auxin and cytokinin-related genes in RNA-Seq data.5.The function of OsDERF8 was related to JA signal,Osderf8 mutant was hyposensitive to Me JA.The JA core transcription factor OsMYC2 was transient overexpressed in rice protoplasts,and the expression of OsDERF8 was up-regulated.Through Promoter-LUC experiment and Y1 H experiment,it is clear that OsMYC2 indirectly regulates OsDERF8 transcription,indicating that transcription factor OsDERF8 plays an important role in leaf senescence and root development during rice growth and development,and is closely related to JA signal.In this study,we found that OsDERF8 positively regulates the JA mediated aging process,and can delay leaf senescence after mutation,thereby enhancing rice yield,The JA signal regulation network is further explored,which has important theoretical,It also provides scientific basis for breeding of excellent varieties..