Physiological Reaponse Characteristics And Transcriptome Analysis Of GhCIPK6 Transgenic Cotton Under High Temperature Stress

As an important economic crop in China,cotton is planted all over the country,among which Xinjiang is the main cotton producing area.With the gradual warming of the global climate and the frequent occurrence of high temperature weather,the fertility of cotton is reduced,and the rate of bud and boll abscission is high,which eventually leads to the reduction of cotton yield.Therefore,the main problem facing today is how to alleviate the stress damage caused by high temperature to cotton.In this study,the offspring of Gh CIPK6 over expression line(OE),RNAi interference line(Ri)and wild-type line(WT)were constructed,and the greenhouse culture method was adopted.After the plants grew to the 6th week,the cotton plants were transferred into the growth box,and the control group at normal temperature of 26℃and the treatment group at high temperature of 42℃(heat stress at 42℃ for 24 h,and recovery 26℃ for 24h).The seedling leaves were removed at 4h,12 h,24h and 48 h respectively,for physiological index determination and transcriptome sequencing.Through the measurement of physiological indexes and analysis of transcriptome sequencing technology,the changes of physiological indexes and differential gene regulation of transgenic seedlings of Gh CIPK6 under high temperature stress were preliminarily understood.The main results of this study are as follows:1.Comparing the morphological changes of seedlings and leaves of the three materials under high temperature,the results showed that the leaves of the over expressed lines were yellow with a large number of spots,followed by the wild-type lines,and the leaves of the RNAi interference lines were only slightly yellow,indicating that the over expressed lines had poor heat tolerance under high temperature stress.2.In terms of photosynthetic characteristics,Pn,Gs,Tr and Ci all decreased first and then increased with the extension of time under high temperature stress.In terms of photosynthetic indexes,the increase rate was slower in over expressed lines,and the increase rate was faster in RNAi interference lines and wild-type lines,and the change trend of chlorophyll relative content was slow.Among the resistance indexes,MAD content increased gradually with the extension of time under high temperature stress,relative conductivity increased first and then decreased,SOD activity increased first,then decreased and then increased,POD activity showed a high level.In RNAi interference lines,MAD content increased first and then decreased,relative conductivity increased first and then decreased,SOD activity increased first and then decreased,POD activity increased slowly,soluble protein content and Pro content were relatively high in the whole period.In plant hormones,under high temperature stress,three kinds of materials with time extension of the IAA content increased gradually,JA content increased after the first drop,RNAi interference lines and wild type lines SA content rise after fall after fall first,ABA content was increased after the first drop,and SA content in the over expression lines increases after the first drop,ABA content is low.Combined with the above indexes,principal component analysis showed that the high temperature resistance of the three materials from strong to weak were RNAi interference lines,wild-type lines,and over expressed lines.3.Transcriptome sequencing was performed on 48 samples from 3 materials.The total number of bases in each sample was 5.95 Gb,and the percentage of Q30 bases was more than 94.09%.The comparison efficiency was above 89.83%.In the wild-type lines,there were 383 differentially up-regulated genes and234 differentially down regulated genes.In RNAi interference lines,there were 315 common differentially upregulated genes and 224 common downregulated differentially regulated genes.In over expression lines,there were 727 differentially up-regulated genes and 396 differentially down regulated genes;Among the three materials,103 genes were up-regulated and 65 genes were down-regulated.4.Analysis of common differentially expressed genes by transcriptome sequencing.According to GO results,wild-type lines are mainly enriched in ATP binding,RNAi interference lines are mainly enriched in some enzyme activities,and over expressed lines are mostly enriched in protein binding,suggesting that the main proteins and ATP respond to adversity stress at high temperature.Three of them were enriched in protein renaturation,stress and 3-β-hydroxyl-δ 5-steroid dehydrogenase activities;KEGG results showed that wild-type lines were mainly enriched in 21 pathways,RNAi interference lines in 10 pathways and over expression materials in 19 pathways,the three materials were enriched in flavonoid biosynthesis,biosynthesis and metabolism of secondary metabolites,and circadian rhythm plant;differential genes were analyzed to identify coding genes related to photosynthesis,plant hormone signal transduction and plant MAPK signal pathway;among transcription factors,differential genes mainly exist in MBY,WRKY,ERF,b HLH,b ZIP and NAC families.