Transcriptome Analysis And Physiological Response Of Upland Rice Seedlings Exposure To Arsenite And Arsenate Stresses

At present,arsenic pollution in soil is severe.Upland rice cultivated in dry fields can effectively reduce the bioavailability of arsenic and help to decrease the arsenic accumulation in grain.The study on physiological characteristics and changes in gene expression patterns of upland rice under arsenic stress has important theoretical significance for the cultivation of crop varieties with low arsenic accumulation.Indica rice variety(DOURADOAGULHA)was choosen to study the effect of arsenite and arsenate on growth and physiology of upland rice.At the same time,combining the transcriptome data analysis,we identified the genes that induced differential expression of upland rice under arsenic treatments.The main results are as follows:1.Transcriptome sequencing results showed that 2983 and 1844 genes were responsive under As(?)and As(?)stresses for 12 h,respectively.The genes with down-regulation were much more than the genes with up-regulation under As(?)and As(?)stress.There were 915 shared genes between As(?)and As(?)treatments.The genes associated with transcriptional regulation,hormone signaling,redox and transporter process were responsive in rice shoots under As(?)and As(?)stress.Much more transcriptional factors related genes were down-regulated under As(?)stress.Hormone signaling related genes were mostly upregulated under As(?)stress.The genes related to redox and transporter process with upregulation were much more than those of downregulation under As(?)and As(?)stresses.2.The expression model of differentially expressed genes screened from transcriptome were analysised for 0,12,24,48,72 h under As(?)and As(?)treatments.The results of genes related to transcriptional factors showed that the genes encoding WRKY4,bHLH and AP2-EREBP were continusely inhibited,while the gene encoding NAC transcriptional factor was induced under As(?)and As(?)stresses.The genes encoding Prx and GST were induced in the early-and mid-term(12 and 48 h)under As(?)stress,but the genes were induced only in the early stage(12 h)under As(?)stress;The genes encoding cytochrome P450 under As(?)and As(?)stress were both induced in the early stage(12 h);The genes encoding oxidoreductase were continusely induced under As(?)and As(?)stress.The genes related to detoxification had differential expression modes under As(?)and As(?)treatments.The genes OsABCC9 and ZIP3 were both responsive under As(?)and As(?)stress.3.Arsenic stress inhibited the antioxidase system of upland rice.Under As(?)and As(?)treatments for 1 and 3 d,the malondialdehyde(MDA)contents in upland rice were 2.7-3.9 times and 3.4-4.3 times of those in the CK treatment,respectively.In contrast,catalase(CAT),peroxidase(POD),superoxide dismutase(SOD)contents were significantly declined under As(?)and As(?)treatments for 1 and 3 d.These indicated that arsenic stress inhibited the antioxidant enzyme system,thus inhibiting the antioxidant reaction of seedlings.In conclusion,in upland rice shoots exposed to As(?)or As(?)treatments,most of DEGs performed downregulation.Furthermore,the DEGs of upland rice shoots responded to As(?)stress were much more than As(?)stress.A novel set of DEGs associated with transcription factors,hormone signaling,redox process and detoxification process were responsive under As(?)and As(?)stress.As(?)and As(?)stress may reduce the contents of antioxidant enzymes by repressing these genes expression.