RNA-Seq analysis reveals an essential role of tyrosine metabolism pathway in response to root-rot infection in Gerbera hybrida

Gerbera hybrida is one of the top five cut flowers across the world, it is host for the root rot causing parasite called Phytophthora cryptogea. In this study, plantlets of healthy and root-rot pathogen-infected G. hybrida were used as plant materials for transcriptome analyis using high-throughput Illumina sequencing technique. A total 108,135 unigenes were generated with an average length of 727 nt and N50 equal to 1274 nt out of which 611 genes were identified as DEGs by DESeq analyses. Among DEGs, 228 genes were up-regulated and 383 were down-regulated. Through this annotated data and Kyoto encyclopedia of genes and genomes (KEGG), molecular interaction network, transcripts accompanying with tyrosine metabolism, phenylalanine, tyrosine, and tryptophan biosynthesis, phenylpropanoid and flavonoid biosynthesis, and plant hormone signal transduction pathways were thoroughly observed considering expression pattern. The involvement of DEGs in tyrosine metabolism pathway was validated by real-time qPCR. We found that genes related with tyrosine metabolism were activated and up-regulated against stress response. The expression of GhTAT, GhAAT, GhHPD, GhHGD and GhFAH genes was significantly increased in the leaves and petioles at four and six dpi (days post inoculation) as compared with control. The study predicts the gene sequences responsible for the tyrosine metabolism pathway and its responses against root-rot resistance in gerbera plant. In future, identification of such genes is necessary for the better understanding of rot resistance mechanism and to develop a root rot resistance strategy for ornamental plants.