Isolation, characterization, and expression of the rice sd-1 (GA20ox) gene ortholog in Eragrostis tef

Abstract

Eragrostis tef (Zucc.) Trotter, a tetraploid cereal of Ethiopia, has a tall and slender stem susceptible to lodging causing yield loss of ~15-45% each year. Genes conferring lodging resistance through the control of plant height involves GA metabolism genes that have not been identified and characterized in E. tef. The aim of this study was to isolate and characterize E. tef GA20ox, a key gene in plant height control. Three putative EtGA20ox orthologs to the rice sd-1 gene were identified in E. tef with characteristic GA20ox domains. Sequence comparison revealed that EtGA20ox sequences share high homology with sorghum, maize and rice sequences. Heterologous expression of the EtGA20ox1a protein in E. coli catalyzed conversion of [14C]-labeled GA12 to GA9. EtGA20ox1a and EtGA20ox1b had highest transcription in the uppermost internodes. EtGA20ox1b, very likely a functional equivalent to the rice sd-1 gene, is predominantly expressed in the stem and could be a target for height regulation. Sequence information will allow advanced biotechnology applications, such as plant transformation and mutant selection, to improve lodging resistance in E. tef.