Study On Cold Resistance Of Malus Sieversii In Different Populations

In this study,it takes Malus sieversii in different populations in Xinjiang area as the research object,we measured and compared the differences of leaf anatomical structures,the differences of physiological response of dormant branches and the differences of MsCBF1,MsCBF2,MsCBF3 and MsCBF4 genes expression levels under low temperature stress.Finally,we combined the experiment result and germination rate to speculate that the strong or weak of cold resistance of Malus sieversii in different populations.We hope to provide reference for cold resistant molecular breeding and selection of fine germplasm resources for Malus sieversii.The main results of this study are as follows:1.The oneness index include the thickness of the leaf,upper epidermis,lower epidermis and palisade tissue and spongy tissue,and the composite index include the palisade tissue and spongy tissue ratio,CTR and SR were measured and analyzed.The results showed that the oneness index can not directly reflect the cold resistance of Malus sieversii,but the composite index can reflect its cold resistance.The strong and weak order was Malus sieversii of Toli county,Malus sieversii of Emin county,Malus sieversii of Gongliu county,Malus sieversii of Huocheng county,Malus sieversii of Xinyuan county.2.The content of soluble protein,soluble sugar,proline and MDA,the SOD activity,POD activity and CAT activity,and the budding rate and electrolyte leakage rate,and the logistic equation was used to fit the change curve of the relative conductivity,and the semi-lethal temperature was calculated under different low-temperatures treatment.The results showed that the strong and weak order was Malus sieversii of Toli county,Malus sieversii of Emin county,Malus sieversii of Gongliu county,Malus sieversii of Huocheng county,Malus sieversii of Xinyuan county.3.The ORF sequences of four CBF genes were cloned by PCR,and named as MsCBF1(GenBank accession number: KX532174),MsCBF2(GenBank accession number: KX532175),MsCBF3(GenBank accession number: KX532176)and MsCBF4(GenBank Registration number: KX532177),respectively.The results of bioinformatics analysis showed that the ORF sequences of four MsCBF genes were 660 bp,711bp,702 bp and 756 bp respectively,and the number of amino acids was 219,236,233 and 251,respectively.Bioinformatic analyses showed that the four MsCBF proteins belonged to water-soluble labile proteins and they had high homology and genetic relationship with other CBF proteins.4.Using fluorescence quantitative PCR technology,analysised of four CBF genes of Malus sieversii in different populations the difference of expression levels in low temperature treatment.The results showed that the four MsCBF genes are induced by low temperatures.The expression levels of four MsCBF genes were different,and their times of expression levels increased were different too.MsCBF1 and MsCBF2 expression levels was lower and MsCBF3 expression was higher after a period of 4? treatment.The relative expression of CBF gene significantly the same in different populations of Malus sieversii on the expression of four MsCBF genes in Malus sieversii of Toli county is relatively high,the expression of four MsCBF genes in Malus sieversii of Xinyuan county is relatively low.According to their expression,the strong and weak order was Malus sieversii of Toli county,Malus sieversii of Emin county,Malus sieversii of Gongliu county,Malus sieversii of Huocheng county,Malus sieversii of Xinyuan county.