Isopentenyltransferase-1 (IPT1) knockout in Physcomitrella together with phylogenetic analyses of IPTs provide insights into evolution of plant cytokinin biosynthesis
01.04.2014
Lindner AC, Lang D, Seifert M, Podlešakova K, Novák O, Strnad M, Reski R, von Schwartzenberg K.
J Exp Bot. 2014;65(9):2533-2543
The rate-limiting step of the biosynthesis of the signaling molecule cytokinin is mediated by isopentenyltransferases (IPTs), found in land plants either as adenylate-IPTs or as tRNA-IPTs. Although a dominant part of cytokinins in flowering plants are synthesized by adenylate-IPTs, the Physcomitrella genome only encodes homologues of tRNA-IPTs. This study utilizing targeted gene knockouts of the chloroplast-encoded IPT1 in Physcomitrella provides evidence for an additional and unexpected tRNA-independent biosynthesis of this signaling molecule in moss. Comprehensive phylogenetic analysis indicates a diversification of tRNA-IPT-like genes in bryophytes probably related to additional functions.
