| Petunia hybrida is famous as a bed flower all over the world.It is also an ideal model plant for molecular biology research.PhMYC2,a member of the b HLH transcription factor family,which is related to stamen fertility and that was found in previous study of our group.Previous studies have shown that MYC2 is a key transcription factor in the jasmonate signaling pathway,JAZ protein is its upstream regulatory factor,and there is interaction between the two.JAZ protein plays an important role in JA-induced stamen development and its abnormal expression can leads to male sterility.In Arabidopsis,the JAZ protein family has been well studied,but the function analysis and interaction network of JAZ prtotein family in Petunia hybrid is still unclear.Here,we conducted a systematic study on the JAZ family proteins of Petunia hybrida to analyze their basic characteristics and functions.The results are as follows:1.12 JAZ family genes were identified from the petunia genome and all the members were successfully cloned,and then bioinformatics methods was adopted to analyze these PhJAZ genes.Multiple sequence alignment indicated that each PhJAZ protein contained a conserved TIFY and Jas domain;the phylogenetic tree was constructed by selecting JAZ family proteins in the dicotyledonous Arabidopsis,tomato,petunia and monocotyledon rice.It was found that all members of the four species could be divided into six groups,namely JAZ I,JAZ II,JAZ III,JAZ IV,JAZ V,JAZ VI,and the JAZ ptotein family of petunia has a closer relationship with tomato;The cis-acting elements in promoter region of the PhJAZ family gene were analyzed,and a variety of cis-acting elements,including hormone response elements,photoresponsive elements,andstress responses,were found.2.The yeast two-hybrid assay was used to verify the interaction between the petunia JAZ family protein and the transcription factor PhMYC2.Except for PhJAZ8,10 and 11,PhJAZ1,2,3,4,5,6,7,9 and 12 could interact with the PhMYC2 protein,suggesting that they may form a complex through interaction,there by inhibiting the transcriptional activity of the transcription factor MYC2 and controlling the expression of downstream genes.3.1The subcellular localization assays of PhJAZ5,PhJAZ9 and PhJAZ12 proteins was carried out.Three corresponding overexpression vectors fused with YFP were successfully constructed andtransiently transformed into Nicotiana benthamiana,then the transformed leaves were observed under laser confocal microscopy.The results showed that these there proteins were localized on the nucleus.4.The exogenous MeJA,weak-light,short-day and low-temperature treatment were conducted on petunia plants to analyze the expression patterns of PhJAZ5,PhJAZ9,PhJAZ12 and PhMYC2 by q RT-PCR.The results were as follows:(1)The expression of PhJAZ and PhMYC2 genes were up-regulated after MeJA stress.but the change of PhMYC2 was far less than that of PhJAZ9 and PhJAZ12.Both PhJAZ9 and PhJAZ12 proteins could interact with PhMYC2,so the expression of PhMYC2 might be inhibited by the PhJAZ9 and PhJAZ12 genes.(2)Under low light stress,each gene was up-regulated in anthers and flower buds with the exception of PhJAZ9.However,the expression of PhJAZ9 was inhibited between 2.5b and3.5b stages of flower bud development,while the expression level of PhMYC2 was significantly increased during these two periods.(3)The expression patterns of PhJAZ gene under short daylight treatment had certain similarity with weak light treatment.PhJAZ9 was mainly expressed in the late developmental stage of anthers and flower buds(1.5a-3.5a),while the expression level of PhMYC2 was roughly opposite,which mainly expressed in the early stages.(4)Under low temperature stress,the expression of PhJAZ gene was up-regulated in the anthers,but PhMYC2 was inhibited.This was consistent with the fact that one of them was a transcriptional repressor and the other was a transcriptional activator,which restricted each other’s expression,and the opposite trend suggested their functional differences. |
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