| Noni(Morinda ciirifolia L.)has high medicinal and health beneficial value;however as a strict tropical spiciec,Noni would suffer chilling injury when the temperature go down below 5 ? degree,which also restrict the development of Noni industryt.A varity of Noni,cold resistance of No.4 which was bred by our team through 16 years of work showed good cold resistance in field,however,the mechanism of its cold resistance is not clear.The purpose of this study is to reveal this mechanism by carrying out physiological biochemical test and analysis in molecular level,to not only lay solid foundation for further research of noni breeding for cold resistance,but also provide good varieties to support the industralization of Noni.The results were as follows:1.Low temperature treatment test showed that Noni No.4 variety could still grow normally after treated at 5 ? degree for 24 hours,while the leaves of the control of Sanya showed waterborne frost-like or even died.It indicated that Noni No.4 variety possesses strong capability of cold resistance.2.All the test including low temperature treatment test,physiological biochemical test and molecular level analysis showed that Noni No.4 variety has the capability of cold resistance.RNA-Seq also found that its cold resistance is the result of function of multiple genes,this matches with the result of physiological biochemical test,which is the characteristic of cold resistance of Noni is a combination of the result multi physiological factors.3.Noni No.4 variety has 1025 differential genes more than that of Sanya after treated at 5 ? for 4 hours,which reflects that the cold resistance No 4 responds faster than Sanya in the early stage of low temperature treatment.The cold responding gene of both No 4 and Sanya reaches almost the same level after treated for 8 hours at temperature of 5 ?,however No 4 has 586 more up-regulated expressing differential genes than Sanya,and 590 less down-regulated expressing differential genes than Sanya,this may explain why No 4 shows better cold-resistance than Sanya4.4286 Unigenes related to cold resistance were found in No 4,they are all either up-regulated expressing or down-regulated expressing differential gene after low temperature treatment for 4 or 8 hours,they also play very important roles in help No 4 to show better cold resistance.5.958 genes and 187 genes related to cold resistance were mapped to the GO database and KEGG database respectively by using GO and KEGG enrichment analysis.Functions of these genes include oxylipin synthesis and metabolism,transcription and regulation,protein phosphorylation,photosynthesis,defense response,primary metabolism,secondary metabolism regulation material synthesis and metabolism,cellular macromolecules biosynthesis and metabolism regulation,gene expression,cell potassium ion transmembrane transport,responding to cold or injury and other stimulation response,transcription factor activity,lipoxygenase activity,protein kinase activity,oxidoreductase activity,phosphotransferase activity,transfructosylation enzyme activity,cell membrane system,and the edge of the plant pathogen interaction pathway,plant hormone signal transduction pathway,two-terpene biosynthesis pathway and so on.In short,cold resistance genes identified related to various aspects of the growth and development of Noni,the character of cold resistance of Noni is combination results of a large number of genes.6.Cold resistance of Noni No.4 related with genes of both ABA-dependent and ABA-independent signal network,ROS network,MAPK signal network,as well as hormone signaling pathway,etc. |
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