Premium
Gain‐of‐function mutations in beet DODA 2 identify key residues for betalain pigment evolution
Author(s) -
Bean Alexander,
Sunnadeniya Rasika,
Akhavan Neda,
Campbell Annabelle,
Brown Matthew,
Lloyd Alan
Publication year - 2018
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15159
Subject(s) - betalain , biology , genetics , mutagenesis , biochemistry , gene , mutant , chemistry , pigment , organic chemistry
Summary The key enzymatic step in betalain biosynthesis involves conversion of l ‐3,4‐dihydroxyphenylalanine ( l ‐ DOPA) to betalamic acid. One class of enzymes capable of this is 3,4‐dihydroxyphenylalanine 4,5‐dioxygenase ( DODA ). In betalain‐producing species, multiple paralogs of this gene are maintained. This study demonstrates which paralogs function in the betalain pathway and determines the residue changes required to evolve a betalain‐nonfunctional DODA into a betalain‐functional DODA . Functionalities of two pairs of DODA s were tested by expression in beets, Arabidopsis and yeast, and gene silencing was performed by virus‐induced gene silencing. Site‐directed mutagenesis identified amino acid residues essential for betalamic acid production. Beta vulgaris and Mirabilis jalapa both possess a DODA 1 lineage that functions in the betalain pathway and at least one other lineage, DODA 2, that does not. Site‐directed mutagenesis resulted in betalain biosynthesis by a previously nonfunctional DODA , revealing key residues required for evolution of the betalain pathway. Divergent functionality of DODA paralogs, one clade involved in betalain biosynthesis but others not, is present in various Caryophyllales species. A minimum of seven amino acid residue changes conferred betalain enzymatic activity to a betalain‐nonfunctional DODA paralog, providing insight into the evolution of the betalain pigment pathway in plants.