Transcriptome Analysis Of The Responses Of Rice (Oryza Sativa) Roots At Seedling Stage To Stress Of Crude Toxins From Rice False Smut Balls

Rice false smut is a panicle fungal disease caused by Ustilaginoidea virens.The typical symptom is the formation of a yellow or greenish-black rice false smut balls in rice spikelets.The disease led to a decline in rice production.Rice false smut balls can also produce mycotoxins,which is harmful to human and livestock.Rice false smut was estimated to occur in one third of the rice cultivation areas in China.Through comparative genomics analysis,there are few genes related to nutrient uptake,polysaccharide degradation and secondary metabolism in the U.virens genome.U.virens lacks plant detoxification enzymes.During floral infection the fungus does not form haustoria1,the structure involved in nutrient uptake for many biotrophs.Therefore,we hypothesize that the crude mycotoxins might act as an important factor during infection.All we know is that the ustiloxins can cause abnormal growth and development of rice.It is helpful to understand internal regulation mechanism of U.virens activity in rice if transcriptome analysis is applied.Therefore,transcriptome analysis was applied to study the response of rice roots at seedling stage to stress of crude toxins from rice false smut balls.A new generation of high-throughput sequencing technology Illumina Hi Seq^TM2500 was used for conventional indica rice Taichung Native 1 roots at seedling stage under stress of crude toxins of rice false smut balls,and then bioinformatic methods were used for gene expression profile and gene function prediction.The results showed that 47.23 G sequence information was obtained.The clean reads of the 6sequencing samples were more than 7.3 G and the base ratios with quality values higher than 30（Q30）in reads were more than 91%from both the treatment and CK.As a result,2665 differentially expressed genes（DEGs）were detected,of which 1591genes were up-regulated and 1074 genes were down-regulated.According to the gene annotation results,the DEGs included the genes encoding peroxidase,transferase,histones,transcription factors and so on.With Gene Ontology（GO）of function enrichment analysis by GO::Term Finder,a total of 53 GO terms（q-value≤0.05）were found to be significantly enriched,including cellular processes,oxidoreductase activity,energy reserve metabolic process,nucleosome assembly and other physio-biochemistry processes.KEGG（Kyoto encyclopedia of genes and genomes）function enrichment analysis showed that 625 DEGs were annotated to 104 pathways.Fifteen pathways reached significant enrichment level（q-value≤0.05）,which were mainly involved in metabolic pathways and secondary metabolites,such as glutathione metabolism,glycolysis/gluconeogenesis,starch and sucrose metabolism and so on.The results of RT-q PCR validation of some DEGs expression trends were consistent with those transcriptome data,which provides further evidence of the reliability of transcriptome data in this study.The research has obtained a large number of DEGs of rice root at seedling stage under the stress of crude toxins condition by high-throughput sequencing technology and the results showed that these DEGs were of great significance in oxidative stress response,energy metabolism related pathways,core histone expression and other physio-biochemistry processes.The results provide some references and theoretical basis for the future study on the mechanism of interactions between the ustiloxins and rice,and between the pathogen U.virens and rice.