Effects of dwarfing genes on root growth and nutrient acquisition of wheat and barley

Joint project with SCRI Genetics Programme

Over 70% of modern wheat cultivars contain semi-dwarfing genes. The aim of this project is to characterise the effects of semi-dwarfing and dwarfing genes on root development and growth of wheat. Cereal cultivars containing semi-dwarfing genes have a reduced stem height phenotype compared to control plants which is caused generally by an interruption of gibberellic acid biosynthesis or gibberellic acid signal transduction.

Semi-dwarfing lines have a reduced coleoptile length, which can affect the early vigour and establishment of temperate cereals, but there are conflicting reports about whether and how semi-dwarfing genes affect the root systems of temperate cereals.

In this study we have used near isogenic lines of Mercia and Maris Widgeon wheats to investigate root growth of young plants grown on agar gel plates and in soil in columns and the field. Our preliminary experiments showed no significant differences between semi-dwarfing lines and the control line in any experiment, nor was there a significant difference between the root length of the two cultivars grown in the field. Total root length of the dwarf lines (Rht-B1c, Rht-D1c, and Rht12) was greater than that of the control and semi-dwarf lines in the gel chambers, but less in both the column and field experiments. Significant differences in root dry mass were also found between Mercia Rht-D1b and the control and semi-dwarf lines in the field experiment, although there were no significant differences in the soil-filled column experiment.

Future expression and localisation studies will test, whether and how gibberellic acid biosynthesis and signal transduction genes influence root growth and development of temperate cereals.