Study On The Differential Expression Of Two Rye Transcriptomes Under Low Temperature Stress

Secale Cereale is a diploid plant of the genus Rye in the Triticeae family of the Gramineae family.It is a relative species of wheat,barley and oats.Rye has outstanding resistance to cold,disease,adversity and drought.It has strong adaptability to poor living environment and can tolerate extreme climatic conditions that other grains cannot tolerate.In this study,Russian winter rye was used as the experimental material and victory rye was used as the control.The physiological indexes and transcriptome of the two kinds of rye were determined by stress treatment at 4℃,and the differentially expressed genes were quantitatively analyzed by q RT-PCR.This study provided a reference for revealing the cold resistance mechanism of Russian winter rye and laid a foundation for further application of Russian winter rye in wheat breeding.（1）Under 4℃ stress,there were differences in the contents of proline,MDA,CAT,POD,SOD,chlorophyll and electrical conductivity between the two rye.The highest proline content was 455.8μg/g in winter rye treated at 4℃for 24h.The highest proline content of victory rye was 140.3μg/g at 4℃for 12 h.The content of malondialdehyde（MDA）inrye decreased gradually under 4℃,and reached the lowest level of0.01nmol/g in winter rye at 72 h.Under 12 h of low temperature stress,the maximum CAT content of winter rye was 404.14U·g^-1 F_W,which was more than four times that of the control,and the difference was significant.The CAT content of victory rye decreased continuously.Under 72 h of low temperature stress,the CAT content of victory rye was only 2.38 U·g^-1F_W,which was 9 times lower than that of the control.The POD content of winter rye increased first and then decreased with the prolonging of4℃stress time.Under 4℃stress for 12 h,the POD content reached the highest of1497.36 U·g^-1 F_W.The POD content of triticale was firstly decreased and then increased,and the highest POD content was 746.77U·g^-1F_W under 4℃stress for 72 h.Under4℃stress for 6 h,SOD content of the two rye was 138.64 U·g^-1 F_W and 107.12 U·g^-1 F_W,respectively.Under low temperature stress,the chlorophyll content of two kinds of rye decreased.The chlorophyll content of winter rye was 1.72 mg/g after 72h of low temperature stress,and the chlorophyll content of Victory rye decreased to 0.52 mg/g after 12h of low temperature stress.Under low temperature stress,the electrical conductivity of the leaves of Victory rye was higher than that of winter rye.At 6 h of low temperature stress,the electrical conductivity of Victory rye was up to 46.53%,and there was no significant change in the electrical conductivity of winter rye leaves.（2）The results of transcriptome sequencing showed that 986and 2891 differentially expressed genes were continuously expressed in winter rye and Victoryrye under4℃stress,respectively.These differentially expressed genes were mainly involved in biological processes,cell components and molecular functions.In winter rye,a total of17 GO entries were enriched in biological processes,three GO entries in cellular anatomical entity,intracellular entity and protein-containing complex were enriched,and 11 GO entries in molecular function,among which binding and catalytic activity accounted for the largest proportion under different stress times.The differentially expressed genes were enriched into 19 KEGG pathways.The analysis of transcription factor family showed that C3H,NAC,MYB,AP2-EREBP,b HLH,C2H2 and WRKY families accounted for a large proportion under low temperature stress.（3）In order to verify the reliability of winter rye transcriptome data,8 genes with significant expression differences during low temperature stress were selected for real-time fluorescence quantitative PCR assay.The results showed that the Unigene25149＿All gene increased significantly at 4℃stress 6 h,CL5072.Contig3＿All and CL13205.Contig2＿All after 24 h,and showed a continuous increasing trend with extended stress time.