The distribution of activity of l-galactose dehydrogenase (l-galdh) in l-ascorbate pathway in vascular and non-vascular plants

Sevan O. Majed

L-galactose dehydrogenase (L-GalDH) in photosynthetic eukaryotes is acting as a key enzyme in the pathway of L-ascorbate biosynthesis. This enzyme is widely distributed in most lineages of photosynthetic eukaryotes. From this study, multiple sequence alignment inferred that there is an evolutionary relationship amongst the L-GalDH sequences in different species of photosynthetic eukaryotes because they have sequence similarities and identities to each other. Secondly, Phylogenetic tree showed that L-GalDH activity is widely evolved in a great variety of eudicots and monocots in comparison to eukaryotic algae. The tree revealed that gene duplication played a major role in evolution of multiple paralogous copies of this within a species called within-species in-paralogs and different species called between-species out-paralogs because the common ancestral gene of this enzyme in vascular and non-vascular plants is diverged from each other at the earliest stage of evolution. Moreover, speciation events can lead to an emergence of different L-GalDH proteins in different species known as orthologs. Thirdly, biochemical and enzymatic tests reveal the presence and absence of the activity of the L-GalDH enzyme in a green plant (Pisum sativum), Chlorophyte (Blindingia minima) and Rhodophyta (Porphyra dioica). The results showed that Blindingia minima has a L-GalDH function but it is very low but porphyra dioica lack it.

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