Effect Of Different Light Qualities On The Synthesis And Emission Of Floral Scent From Snapdragon

The floral scent has important ecophysiological functions,and the synthesis and emission are influenced by environmental factors.Light quality is an important environmental factor to impact the synthesis and emission of floral scent,but the regulation mechanism is largely unknown.Jasmonic acid is an important signaling molecule in plants regulating the synthesis of terpenoids,which suggested that Jasmonic acid can control the synthesis of floral scent.Snapdragon(Antirrhinum majus)is a perennial herb plant of Scrophulariaceae,and is a model plant in the study of floral scent.In this paper,using snapdragon as the plant material,after treatment with different light qualities,the floral scent was collected by dynamic headspace method,and analysed by ATD-GC/MS technique,to reveal the effect of light quality on floral scent.The expressions of key genes in the synthesis of terpenoids by qRT-PCR including geranylgeranyl diphosphate synthase(GPS),myrcene synthase(MYS),and ocimene synthase(OCS)to investigate the molecular mechanism.The key genes mediating the synthesis of jasmonic acid were cloned including d,and the spatial-temporal expressions were also measured,to explore the signaling role of jasmonic acid in the synthesis regulation of floral scent by different light qualities.The main results are as follows.1.Using snapdragon as experimental material,three key synthase genes in jasmonic acid synthesis,named AmOPR,AmAOC and AmOPR were cloned by homologous cloning using RT-PCR and RACE-PCR technique.The length of AmOPR is 2649 bp,which encodes a protein containing 883 amino acids.The theoretical molecular weight is 100.52 KD.The length of AmAOC is 762 bp,which encodes a protein containing 253 amino acids.The theoretical molecular weight is 27 KD.The length of AmOPR is 1128 bp,which encodes a protein containing 375 amino acids.The theoretical molecular weight is 42 KD.2.The expressions of AmLOX,AmAOC,AmOPR presented tissue specificity.The gene expressions were all observed in roots,stems,leaves,and flowers,but the expression levels were different.The highest expression levels were found in flowers.In flowers,the expressions of AmLOX and AmOPR increased gradually with the flower development.The expression of AmAOC firstly decreased with the flowering stages,and arrived at the lowest level at the full flowering stage,and then increased at wilting stage.3.Under different light qualities,no obvious difference was found in components of floral scent,,but the release amounts showed significant difference.Among the floral volatile categories,the released amounts of terpenoids and aldehydes were obviously influenced by light quality.The release amounts of terpenes and aldehydes were in high levels at blue and green lights.Under red,blue,and white lights,the release amounts of terpenoids for 6h treatment were higher than those for 2h treatment,but the under green light the result was contrary Red light promoted the emission of aldehydes.4.Green light promoted the expression of GPS and MYS.The expression of MYS was in a lower level under white light than under other light qualities.Blue light promoted the expressionof OCS,and red light promoted the expression of MYS and OCS.The AmLOX expressed in a high level under red light,and a high expression level of AmAOC under both red and blue lights.While The AmOPR showed the higher expression level under white light than under other light qualities.No obvious relationship between the expressions of key synthases gene of jasmonic acid and the emission of floral scent under different light qualities.Thus,whether jasmonic acid played a role in the regulation of floral scent in response to light quality needs to be investigated in the future study.