GA和ABA信号转导关键基因在不同温度处理‘凤丹’牡丹种子中的表达分析

Expression Analysis of GA and ABA Signal Transduction Genes in Peaonia ostti ‘Fengdan’ Seeds Under Different Temperature Treatments

采用超高效液相色谱—串联质谱(UPLC–MS/MS)的方法测定了25℃和4℃处理下‘凤丹’牡丹(Peaonia ostti‘Fengdan’)种子播种后8个时期的激素含量变化,并利用qRT-PCR分析GA_3和ABA信号转导4个关键基因的表达模式。结果表明:25℃处理下种子可以正常萌发,而4℃处理下种子在播种后100 d内未萌发。两种温度处理下种子中GA_3含量均呈现先升高后降低的趋势,但25℃处理播种后17 d(下胚轴萌发期)显著高于4℃处理;在25℃处理种子中ABA含量逐渐降低,而4℃处理下短时间降低后迅速升高,且在播种后7~17 d显著高于25℃处理。推测25℃处理下较高含量的GA_3可以促进种子萌发;而4℃处理下较高含量的ABA抑制种子萌发。qRT-PCR分析表明,PoGID1a和PoGAI的整体表达模式与GA_3含量变化趋势类似,呈现先升高后降低的趋势,但播种前期25℃处理下PoGID1a表达量一直显著高于4℃处理,而PoGAI却显著低于4℃处理(21 d除外);PoGAMYB4在25℃处理下呈升高趋势,在4℃处理下先升高后降低,但播种3 d后25℃处理显著高于4℃处理;PobZIP表达趋势与ABA含量变化相似,4℃处理显著高于25℃处理。故推测牡丹种子萌发受GA和ABA调控,GA通过调控信号转导关键基因PoGAMYB4、PoGID1a和PoGAI促进种子萌发,其中PoGAMYB4和PoGID1a可能受GA正调控,而PoGAI受GA负调控;ABA可能通过正调控PobZIP抑制种子萌发。

Hormone content in Peaonia ostti‘Fengdan’seeds from 8 stages after sowing under 25 ℃ and 4 ℃ treatments was analyzed by ultra-performance liquid chromatography/tandem mass spectrometric（UPLC-MS/MS）method. Four signal transduction genes expression（PoGID1 a,PoGAMYB4,PoGAI and Pob ZIP）were tested by qRT-PCR. The results showed that‘Fengdan’seeds could germinate under 25 ℃ treatment,while it could not germinate within 100 days after sowing（DAS）under 4 ℃ treatment. The GA3 content increased first and then decreased under two treatments,while it was significantly higher in seed at 17 DAS（seed hypocotyls germination stage）under 25 ℃ treatment than that under 4 ℃ treatment. The ABA content decreased continuously under 25 ℃ treatment,while it increased rapidly after a short period decrease under 4 ℃ treatment,and it was significantly higher than 25 ℃ treatment at 7–17 DAS. It was deduced that the high level of GA3 content at 17 DAS under 25 ℃ treatment could promote seed germination and the high level of ABA content under 4 ℃ treatment inhibited seed germination. The expression patterns of PoGID1 a and PoGAI under 25 ℃ and 4 ℃ treatments showed an up-to-down trend,while the expression level of PoGID1 a and PoGAI（21 d excluded）were higher and lower,respectively under 25 ℃ treatment than that under 4 ℃ treatment. The expression pattern of PoMYB4 showed an increasing trend under 25 ℃ treatment,while it increased slightly at the initial stages and then decreased under 4 ℃ treatment. On the whole,the expression level of PoMYB4 under 25 ℃ treatment was significantly higher than that under 4 ℃ treatment,at 3–100 DAS. The expression pattern of Pob ZIP was similar to ABA content change,and it was significantly higher under 4 ℃ treatment than that under 25 ℃ treatment. Therefore,it was suggested that seed germination was controlled by GA and ABA. GA promoted seed germination by positively regulating GA signal transduction PoGID1 a and PoGAMYB4 and negatively regulated PoGAI,while ABA inhibited seed germination by positively regulating ABA signal transduction Pob ZIP expression.