| Nostoc flagelliforme(Nostoc flagelliforme Born.et Flah.)is a kind of main biological nitrogen fixation cyanobacterium in arid desert area.In the long process of evolution,N.flagelliforme have being a spectial drought tolerance mechanism different from toher terrestrial plants,it can survive for decades or even centuries in extremely dry conditions,and quickly restore metabolic activity when it rehydrated.The research will be of a great significance for understanding molecular mechanism of drought-tolerance in N.flagelliforme and its evolutionary mechanism,will provide a reference for terrestrial cyanobacteria or higher plants in response to drought stress,and will lay a foundation for molecular basis and gene resources of drought tolerance on plant breeding,particularly in corps.N.flagelliforme is rich in colloid sheath,pigment and polysaccharide.The Omega RNA extraction kit,Trizol method,Tiangen RNA extraction kit and their promoted methods were performed in RNA extraction from N.flagelliforme colonies.The results showed that Trizol method could not extract total RNA successfully;Omega kit could be used to obtain fractionation total RNA,but RNA was accompanied by impurity pollution;Tiangen RNA extraction kit could successfully extract total RNA,and that 23 s and 16 s RNA stripes were clear,A260/A280 and A260/A230 were 2.06 and 2.08,respectively,after the protocol of Tiangen RNA extraction kit was improved.These results laid a foundation for the further research on transcriptome in N.flagelliforme.In order to 4 hours after rehydration(4HAR)of N.flagelliforme colonies as the control group,the 6 hours after dehydration(6HAD)and 48 hours after dehydration(48HAD)of the colonies as two treatment.RNA was extracted,DNA library was constructed,transcriptome was sequenced and data was analysed.Connector and the low quality of the total reads were removed from the original reads,there were 5965413 clean reads in 4HAR group,there were 6269853 clean reads in 6HAD group,there were 9041367 clean reads in 48HAD group.Differential gene expression analysis was employed after quality assessment.The results showed that the significantly up-regulated and down regulated genes were 379 and 36 in 6HAD treatment,respectively.The significantly up-regulated and down regulated genes were 502 and 158 in 48HAD treatment,respectively.GO enrichment analysis showed that,there was a total of 1000 terms in 6HAD group,but 15 terms were significantly affected by dehydration of them,13 terms belong to the biological process,2 terms belong to the molecular function,threr were not cellular components term items.In the biological process related terms,there were 36 differential genes in the item of single-organism transport,31 differential genes were up-regulation and 5 differential genes were down-regulation.Differential genes were up-regulation in other 14 significant terms.There was a total of 1266 terms in 48HAD group,there were 756 items belonging to the biological process,378 items belonging to the molecular function,132 items belonging to the cell component,and there were not significant enrichment in all items.Comparative analysis was employed with the aid of KEGG database.The results showed that there were 36 differential genes in 6HAD group,there were 63 differnetial genes in 48HAD group.There were 5 significant pathways in 6HAD,there were starch and sucrose metabolism,biosynthesis of unsaturated fatty acids,photosynthesis,pentose phosphate pathway and carotenoid biosynthesis pathway,respectively.There were 19 differentially expressed genes in the above 5 pathways.There were 16 up-regulated genes and 3 down-regulated genes.While there were 2 significant pathways in 48HAD treatment,including 9 up-regulated genes. |
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