| The annual hybrid offspring of excellent strains of‘Fan Jing’Rhododendron as materials,studied on Rhododendron under different low temperature(0℃,-3℃,-6℃and-9℃)and control(25℃)the physiological responses and transcriptome analysis,thus the low temperature resistant physiological response mechanism and facilities cultivation theory with the technical support for the Rhododendron.The results are as follows:(1)found that responses to low temperature stress by‘Fan Jing’Rhododendron:0℃and-3℃under low temperature stress,‘Fan Jing’Rhododendron are fine,the growth,chlorophyll content,photosynthetic rate,oxidoreductase,osmotic adjustment and chloroplast ultrastructure had no significant difference with CK;-6℃ and-9℃under low temperature stress,the growth inhibition phenomenon began to appear in different degree,the growth state,chlorophyll content,photosynthetic rate,oxidoreductase,osmotic adjustment and chloroplast ultrastructure changes relatively remarkable or very remarkable.The main performance is: at-6℃and-9℃under the low temperature stress,the growth status of leaves,leaf small macula and fold wilting,but at-6℃to continue normal growth,especially in the-9℃low temperature stress,decrease obviously the chlorophyll content,photosynthetic rate decreased with the increase of stress time,photosynthesis,decrease.At-9℃under low temperature stress,the relative conductivity and MDA content increased with the increase of stress time and rising,soluble sugar and soluble protein content decreased significantly,proline contents were on the rise,CAT,SOD and POD and other antioxidant enzymes are increased after the first drop,palisade cells began to accumulate a large number of sediments become irregular in shape,cell gap becomes larger,epidermis,thickness of palisade tissue decreased significantly,the chloroplast in the cell of irregular distribution and less obvious swelling of chloroplast lamellae become large,loose structure,matrix thin,starch grains and osmiophilic granules increased significantlyand larger.The above results show that the Rhododendron has strong resistance to low temperature stress.(2)The use of RNA-seq technology to‘Fan Jing’Rhododendron of transcriptome high-throughput sequencing,the sequencing results of gene function note,analyzed the differences of gene expression after low temperature stress,and GO and Pathway enrichment analysis of differential gene.The results showed that: a.under low temperature stress,‘Fan Jing’Rhododendron-6℃low temperature treatment(T)and under normal conditions‘Fan Jing’Rhododendron(CK)the difference between the expression of 10829 genes(CK-VS-T)gene expression,6347 up-regulated,4482 down regulated genes.b.there are 5 CK-VS-T significant enrichment of Pathway,which is closely related to the resistance response,most of the Pathway and plant secondary metabolites such as synthesis pathway,oxidative phosphorylation pathway,ribosome metabolic pathway.In contrast to c.T and CK,a total of 10829 differentially expressed genes,of which the vast majority of highly expressed genes were unknown genes,suggesting that "there may be a lot of and response to cold stress or other abiotic resistance related genes of unknown specific‘Fan Jing’Rhododendron.These varieties,we need to further tap.d.it is involved in the expression of several gene in the anti stress pathway,and changes in the expression of ALDH,ERF,MYB and b HLH under low temperature stress.This suggests that there may be a lot of pathways related to the response to low temperature stress or other abiotic resistance in‘Fan Jing’Rhododendron.(3)Based on study of transcriptome,using quantitative real-time PCR detection,low temperature stress,up-regulated and down regulated expression of 24 genes were four genes ALDH,ERF,MYB and b HLH in the family(including all ALDH family transcription factor,expression of ERF,MYB and the b HLH family has also raised the transcription level of the transcription level),differential expression in‘Fan Jing’Rhododendron leaves,and verify the transcriptome results,finally screened genes associated with cold or Rhododendron genes.The results show that the quantitative results although the magnitude of the change in the expression of some differences,but from the trend of expression of 24 genes,which in addition to a transcription factor,relative expression of other gene are relatively high.Real time fluorescent quantitative analysis results and transcriptome consistent description of transcriptome data obtained by sequencing the Illumina is reliable,and the relative expression of31795,10108 and 937 three genes were higher,that these 3 genes may be in theprocess of Rhododendron low temperature stress,promote the exercise of cold related functions.The relative expression of the highest 31795 aldehyde dehydrogenase(ALDH)transcription factor family of transcription,through the research of the gene related to the previous we found that the expression induced by various abiotic stress,its biological function is only for reference to the Arabidopsis genes of other plants such as speculating,whether it is the function of such whether or not,and is also involved in other life and metabolic activities,further research is needed. |
