外源IBA对无花果扦插苗抗氧化特性及IAA生物合成途径的影响

Effects of exogenous IBA on antioxidant property and IAA biosynthesis pathway in cuttings of Ficus carica

【目的】探讨适宜浓度吲哚丁酸(IBA)对无花果插穗生根萌芽、抗氧化性及生长素生物合成途径相关基因表达的影响,为其应用于无花果的育种、繁殖、推广和种植提供理论依据。【方法】以‘波姬红’无花果品种硬枝为插穗,观测不同质量浓度IBA(0,30,45,60,90 mg/L)处理下插穗生根性状、抗氧化特性,并对45 mg/L IBA处理及对照组的扦插枝条中段的腋芽进行转录组分析。【结果】(1)无花果插穗萌芽率和生根率在45 mg/L IBA处理时达到最大值,并与其他处理和对照差异显著。(2)随IBA浓度增加,插穗SOD和CAT活性先下降后上升,并均在45,60 mg/L IBA处理下显著低于对照,而POD活性无显著变化;各浓度IBA处理插穗中MDA和H2O2含量均显著高于对照,且45 mg/L IBA处理MDA显著低于其余处理。(3)45 mg/L IBA处理及对照组中共存在6 879个差异表达基因,KEGG富集显示有10个差异途径,GO富集分析表明生物学过程和分子功能为主要的生物学途径;与CAT、SOD相关的基因集中富集在过氧化物酶体通路上,POD相关基因则富集在苯丙烷生物合成通路中;IAA生物合成途径中代谢相关基因FcGH3显著上调表达,与信号转导相关基因FcAUX1、FcARG7和FcARF等显著下调表达。【结论】外源IBA处理会导致无花果插穗抗氧化酶和IAA生物合成途径中相关基因表达的差异变化,增强插穗抗逆性,促进插穗生根、萌芽、成苗,并以外源45 mg/L IBA促进效果最好。

[Objective]Exploring the effects of suitable concentrations of indole butyric acid(IBA)on rooting and sprouting as well as on antioxidant property and gene expression related to growth hormone biosynthesis pathway of fig(Ficus carica L.) cuttings may provide theoretical basis for its application in figbreeding, propagation, promotion, and planting. [Methods] The hard branches of ‘Bojihong’ fig varietywere used as cuttings to analyze the effects of IBA treatments (0, 30, 45, 60, 90 mg/L) on the rootingtraits and antioxidant properties of the scions, as well as analyzed the transcriptome of axillary buds in themiddle part of fig cuttings under 45 mg/L IBA treatment. [Results] (1) The germination and rooting ratesof fig spikes reached the maximum at 45 mg/L IBA and differed from other treatments and the control.(2)With the increase of IBA concentrations, the SOD and CAT activities of spikes showed a trend of firstdecreasing and then increasing, and both were lower than the control at 45 and 60 mg/L IBA, while PODactivity was unchanged between the treatment and control. MDA and H2O2 contents in the spikes underIBA treatments were higher than the control, and MDA content in the spikes at 45 mg/L IBA was lowerthan other treatments. (3) Transcriptome analysis showed that there were 6 879 differentially expressedgenes at 45 mg/L IBA. KEGG enrichment showed that there were 10 differential pathways. GO enrichmentanalysis indicated that the biological processes and molecular functions were the main biologicalpathways;the genes related to CAT and SOD were enriched in peroxisomal pathway, while the genes relatedto POD were enriched in phenylpropane biosynthetic pathway. The metabolism-related gene FcGH3was up-regulated in the IAA biosynthesis pathway, and the genes related to signaling, such as FcAUX1,FcARG7, and FcARF, were down-regulated. [Conclusion] IBA treatment induced the expression of genesencoding antioxidant enzymes and genes involved in IAA biosynthesis pathway of fig spikes, enhancedresistance to stress, and promoted rooting, sprouting, and seedling formation and 45 mg/L IBA had thebest effect.