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.
