Analysis of Differentially Expressed ESTs for Gingerol Production and Validation of 3-Ketoacyl CoA Thiolase Gene Expression in High Gingerol Yielding Genotypes of Ginger (Zingiber Officinale Rosc.)

Abstract

The pharmacologically important bioactive gingerols, present in the rhizomes of ginger are formed from the intermediates of phenylpropanoid pathway. Ginger genome is little exploited and studies on gingerol synthesis are very limited. However, Kerala Agricultural University, India, could develop ginger somaclones with different levels of gingerol content. In the present investigations, analysis of differentially expressed ESTs for gingerol production and validation of identified EST for high gingerol content were carried out. The differentially expressed ESTs for gingerol production in ginger somaclone B3 obtained through Suppression Subtractive Hybridization (SSH) from a previous doctoral research available at Centre for Plant Biotechnology and Molecular Biology (CPBMB) were analyzed and functionally annotated using different bioinformatic tools such as BLASTx, BLASTn, Interprosaan and Blast2GO. Fifteen quality differentially expressed EST sequences in ginger somaclone B3, eleven from rhizome and four from leaf were analyzed. The rhizome ESTs showed maximum similarity hits with Boechera divaricarpa while the leaf ESTs showed similarity with Musa accuminata subsp. malaccensis. The gene ontology distribution of rhizome ESTs showed its involvement in metabolic and cellular processes. From the previous doctoral research, the gene 3ketoacyl CoA thiolase (Thiolase) was identified to play a key role in gingerol synthesis. The expression of Thiolase gene was validated in high gingerol yielding ginger varieties viz. Athira, Karthika, Aswathy and somaclone B3 using Real Time PCR with low gingerol yielding cultivar Maran as control. The highest expression of 3-ketoacyl CoA thiolase gene was recorded in the ginger variety Athira (2.737 fold) followed by variety Karthika (2.150 fold), variety Aswathy (2.018 fold) and somaclone B3 (1.992 fold) over the control cultivar Maran thus validating the role of gene 3-ketoacyl CoA thiolase (Thiolase) in gingerol production.