外源乙烯利与1-MCP处理对桑椹中乙烯和花青素相关代谢基因表达的影响

摘要

[Objective] Ethylene,a kind of phytohormone,plays a critical role in fruit maturation and senescence.This study aims to explore the effect of ethylene on expression of the genes involved in ethylene of mulberry fruit,in order to provide a basis for exploring the economic value of mulberry using the methods of molecular biology.The total sugar content and anthocyanin content were detected and transcriptional expression of ethylene and anthocyanin related genes were analyzed in the variety 'Jialing 40' (Morus alba 'Jialing 40') fruits.[Method] The mulberry fruits were sprayed with ethephon(100 mg·L-1) 21days (21DAF) and 26 days (26DAF) after full-bloom,respectively and 1-MCP(0.5 μL·L-1) was applied after harvest.Anthocyanin content and total sugar content was measured,total RNA of mulberry were extracted and reverse transcribed to synthesize cDNA.The relative transcriptional expression of ethylene biosynthesis related genes MaACO2 and MaACS3,and signal transduction related genes like MaETR1,MaETR2,MaCTR1,MaEIN2,MaEIL2,and anthocyanin related genes like MaDFR and MaANS were analyzed by using qRT-PCR.[Result] Compared with the control,the anthocyanin and total sugar content were significantly increased by ethephon but decreased by 1-MCP,and the expression level of anthocyanin related genes were up-regulated by ethephon at 21DAF and 26DAF.At 21DAF,the expression level of ethylene related genes were up-regulated by ethephon,but the transcripts of MaACO2,MaACS3 and MaEIL2 were decreased by 1-MCP;MaETR1,MaCTR1,MaEIN2 were up-regulated significantly but the transcripts of MaETR2 displayed a non-significant change by 1-MCP.At 26DAF,the expression level of ethylene related genes were down-regulated by 1-MCP and changed differently by ethephon.After 32 hours,MaACO2,MaETR1,MaETR2,MaEIN2 and MaEIL2 were up-regulated while MaACS3 and MaCTR1 were down-regulated by ethephon compared with the control.[Conclusion] Ethephon could up-regulated the transcripts of ethylene biosynthesis and anthocyanin biosynthesis related genes and influence the ethylene signal transduction related genes,but 1-MCP inhibited the ethylene signal transduction related genes and blocked ethylene signal transduction.Accumulation of anthocyanin and total sugar content were accelerated by ethephon,but inhibited by 1-MCP.%[目的] 以桑品种'嘉陵40号'的桑椹为试验材料,探究乙烯在桑椹发育进程中的作用和乙烯相关基因的表达模式,为今后有效开发桑椹的经济价值和通过分子生物学手段调控桑椹成熟期提供理论依据.[方法] 桑盛花期后21天(21DAF)和26天(26DAF),分别用100 mg·L-1乙烯利喷洒桑椹表面,采摘后桑椹经0.5 μL·L-1乙烯抑制剂1-MCP熏蒸处理,测定其花青素和总糖含量,并提取桑椹的总RNA及合成cDNA模板,利用实时荧光定量PCR (qRT-PCR)分析乙烯生物合成基因MaACO2和MaACS3,乙烯信号转导基因MaETR1,MaETR2,MaCTR1,MaEIN2和MaEIL2,以及花青素生物合成下游基因MaDFR和MaANS的转录表达.[结果] 桑椹经过乙烯利处理后,花青素含量和总糖含量与对照相比都有明显增加,与花青素合成有关的基因表达也受乙烯利上调,经1-MCP熏蒸的桑椹花青素含量和总糖含量与对照相比都有所下降.在21DAF桑椹中,乙烯相关基因的表达经乙烯利处理后显著上调,而对1-MCP具有不同的响应模式,其中,MaACO2,MaACS3以及MaEIL2表达下调,MaETR1,MaCTR1和MaEIN2的表达量在各时段显著上调,MaETR2表达量在12 h无明显变化,其他时段上调.26DAF桑椹中,经1-MCP的熏蒸而下调了乙烯各基因的表达,而乙烯利的处理对各基因表达具有不同的影响,与对照相比,处理后32 h,MaACO2,MaETR1,MaETR2,MaEIN2 和MaEIL2的表达上调,MaACS3和MaCTR1的表达则下调.[结论] 乙烯利处理能够诱导桑椹乙烯生物合成和花青素生物合成相关基因的上调表达,对乙烯信号转导基因也有一定调控作用,且能促进桑椹花青素和总糖含量的积累,并能加快桑椹的发育进程.乙烯抑制剂1-MCP的熏蒸能抑制乙烯信号转导各元件基因的表达,阻止乙烯信号转导和传递,且抑制桑椹中花青素和总糖含量的积累.