Acta Horticulturae Sinica ›› 2022, Vol. 49 ›› Issue (8): 1747-1760.doi: 10.16420/j.issn.0513-353x.2021-0562

• Research Papers • Previous Articles     Next Articles

Cloning and Functional Analysis of the MbEGS Gene from Melaleuca bracteata

QIU Ziwen1,3, LIU Linmin1, LIN Yongsheng1, LIN Xiaojie1, LI Yongyu1,2,*(), WU Shaohua1,2,*(), YANG Chao1,2,*()   

  1. 1. College of Horticulture,Fujian Agriculture and Forestry University,Fuzhou 350002,China
    2. Institute of Natural Products of Horticultural Plants,Fujian Agriculture and Forestry University,Fuzhou 350002,China
    3. Agricultural Science and Technology Development Center of Chaozhou in Guangdong Province,Chaozhou,Guangodng 521000,China
  • Received:2021-11-07 Revised:2022-03-24 Online:2022-08-25 Published:2022-09-05
  • Contact: LI Yongyu,WU Shaohua,YANG Chao;;


Melaleuca bracteata is rich in essential oil,the main component of which is methyl eugenol with the content is as high as 86.5%. Eugenol is the precursor for the synthesis of methyl eugenol,but the biosynthetic pathway of essential oil is not clear. Based on the transcriptome databases of Melaleuca bracteata,two eugenol synthase genes(MbEGS1 and MbEGS2)were identified and cloned from Melaleuca bracteata. The coding sequences(CDS)of MbEGS1 and MbEGS2 were 963 and 972 bp in length,encoding 320 and 323 amino acids,respectively. Multiple sequence alignment and phylogenetic tree analysis showed that the deduced proteins MbEGS1 and MbEGS2 had the highest similarity (65.92% and 63.89%)with CbIGS1. qRT-PCR analysis showed that MbEGS1 and MbEGS2 were expressed in flowers,leaves and stems of Melaleuca bracteata. The highest expression level was observed in flowers,followed by leaves and stems,which was similar to the eugenol content in different tissues of Melaleuca bracteata,showing a significant positive correlation between the gene expression and eugenol content. MbEGS1 was expressed in roots of Melaleuca bracteata,and the expression level was higher than that in stems and lower than that in leaves. However,MbEGS2 was not expressed in roots. When MeJA was used to treat Melaleuca bracteata,MeJA could induce the expression of MbEGS1 and MbEGS2 and eugenol synthesis,which showed a trend of first increase and then decrease. Treatment with MeJA at 0.1 mmol · L-1 had the most significant effect on gene expression,and their transcription levels were positively correlated with the eugenol content. Subcellular localization showed that MbEGS1 was mainly located in plant cell membrane and nucleus,and MbEGS2 was mainly located in plant cell membrane. Ectopic expression of MbEGS1 and MbEGS2 showed that overexpression of MbEGS1 and MbEGS2 promoted the synthesis of eugenol in Fragaria vesca(Yellow Wonder). The results show that both MbEGS1 and MbEGS2 genes are involved in eugenol biosynthesis.

Key words: Melaleuca bracteata, eugenol synthase, gene cloning, expression analysis, functional identification

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