COMPARATIVE PHYLOGENETIC ANALYSIS OF METHYLERYTHRITOL-4-PHOSPHATE (MEP) PATHWAY GENES IN ASTERAECAE FAMILY

摘要

Stevioside glycosides (SGs) are a class of diterpene glycosides being produced by leaves of Stevia rebaudiana. Stevia is getting agricultural importance due to the production of natural sweetener steviol glycosides, also called as zero-calorie sweeteners. Earlier it was thought that steviol was synthesized from Kaurene via MVA pathway but later on it was concluded that precursors of steviol are actually synthesized via the plastid localized methylerythritol 4-phosphate (MEP) pathway. In total, seventeen enzymes are used in this biosynthetic pathway. Each enzyme plays a significant role in the subsequent production of rebaudioside A and other SGs. In order to understand those enzymes functionally, understanding of those genes evolution basically in the Asteraceae family is highly warranted. In this study, the National Center for Biotechnology Information (NCBI) was searched to retrieve amino acid sequences that encode MEP pathway enzymes homologs. A number of MEP pathway enzymes’ amino acid sequences from the Asteraceae family were phyleticaly analyzed to light the way for the evolution characteristics of sweetener-producing plants homologs. The study is about to interpret the evolutionary relationships of Stevia rebaudiana with other plants in the same or different genus in the family Asteraceae.