| Prunus sibirica is a deciduous plant of Prunus genus in Rosaceae,which has high ecological value,economic value and ornamental value.P.sibirica blossoms early in spring and is vulnerable to late frost.Severe cooling and frost will lead to the freezing of floral organs of P.sibirica,resulting in reduced or even no harvest,bringing huge losses to production and seriously hindering the development of P.sibirica industry.In this study,the freezing-resistant clones of floral organs of P.sibirica were taken as the research object.The low temperature(-4 ℃)was controlled by artificial simulation.The pistil samples of the freezing-resistant clones and the control were collected after 0 h,15 min,30 min,1 h,and 2 h of stress treatment,respectively.The physiological indexes,transcriptome sequencing,fluorescence quantitative PCR verification,and changes in endogenous hormone content were studied to explore the freezing-resistant response of floral organs under different low temperature treatments,and the interaction between freezing-resistant related genes and changes in endogenous hormone content and signal transduction,which laid a theoretical foundation for the study of freezing-resistant mechanism of floral organs of P.sibiricat.The main research results are as follows :(1)Under each time gradient of low temperature stress treatment,the freezing resistance of pistil of 453(freezing resistant clone)was stronger than that of CK(371);the freezing rate of pistil increased with the increase of stress time,and the fruit setting rate decreased.The relative conductivity,MDA,soluble protein and soluble sugar contents of No.453 and CK increased gradually.POD activity and SOD activity increased first and then decreased;the electrical conductivity and MDA content of 453 were lower than those of CK,while POD activity,SOD activity,soluble protein content and soluble sugar content were higher than those of CK.The physiological indexes of No.453 were significantly different at 1 h and 2 h of stress.(2)Transcriptome analysis of P.sibirica blossom organs obtained a total of 15,228 differential genes,of which 6,630 were up-regulated genes and 8,598 were down-regulated genes.The differential genes were compared and screened,and multiple gene families related to frost resistance such as B3,MYB,AAA,zf-GRF,b HLH,TCP,WD40,HSP,PPR,ZIM and AP2.Real-time fluorescence quantitative verification of frost resistance-related genes showed that the expression levels of PsADP,PsPYL2,PsPOD24,PsPPR2,PsTPR,PsWD40,PsIAA20,PsSA2 and PsSnakin-2 genes in clone 453 were significantly indigenous,and the expression levels in CK were low,which positively regulated the frost resistance of floral organs.The expression of PsPME1,PsPRA1,PsATP1,PsSBT1,PsWRKY22,PsTCP2,PsSIZ1,PsNTF2 and PsRAV2 in 453 was low,and the expression in CK was significant,which negatively regulated the frost resistance of flower organs.GO functions mainly include growth,metabolic process,reproductive process,response to stimulus,signal transduction,antioxidant activity and catalytic activity.KEGG pathway enrichment mainly includes amino acid metabolism,photosynthesis,plant hormone signal transduction,starch and sucrose metabolism.(3)A total of eight plant hormones including abscisic acid,auxin,cytokinin,ethylene,gibberellin,jasmonic acid,salicylic acid and monocrotolactone were detected.Among them,abscisic acid,salicylic acid,gibberellin,auxin,cytokinin hormone(except DHZR)of 453 were lower than CK,jasmonic acid hormone content of 453 was higher than CK.The metabolic pathways and related genes related to plant hormones(IAA,GA,DHZR and JA)metabolism were screened.After 15 min of low temperature stress,IAA and GA were down-regulated,and DHZR and JA were up-regulated.A total of seven metabolic pathways were identified from the KEGG classification and enrichment results,which were divided into two categories: metabolism and environmental information processing metabolism,and the hormones involved in metabolism were the most. |
PDF Full Text Request