Phene Synergism Between Root Hairs and Basal Root Growith Angle for Phosphorus Acquisition in Common Bean
M. Miguel; J. P. Lynch
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A poster presented at the 2012 Global Pulse Researchers Meeting, Kigali, Rwanda- “Transforming Grain-Legume Systems to Enhance Nutrition and Livelihoods”. Abstract: Multiple root traits affect phosphorus acquisition, including root hair length and density (RHLD), and basal root growth angle (BRGA). We hypothesized that shallow BRGA and long root hairs are synergetic for phosphorus acquisition, meaning their combined effect is greater than the sum of their individual effects. The purpose of this study was to evaluate this hypothesis by quantifying the effect of root hairs and basal root growth angle alone and in combination among closely related genotypes. We established a set of field experiments with Recombinant Inbred Lines (RILs) of common bean (Phaseolus vulgaris L.) grouped in four distinct root phenotypes: long root hairs and shallow basal roots; long root hairs and deep basal roots; short root hairs and shallow basal roots; and short root hairs and deep basal roots. Results revealed substantial synergism between the two phenes. Long root hairs increased shoot biomass under phosphorus stress by 89.3% while shallow roots increased shoot biomass by 57.7%. Genotypes with both long root hairs and shallow roots had the greatest biomass accumulation, 298% greater than short-haired, deep-rooted phenotypes. Shoot biomass and phosphorus content of genotypes with long root hairs on deep roots and shoot biomass of genotypes with short root hairs on shallow roots did not differ, but were greater than those of genotypes with short root hairs on deep roots. We conclude that the morphological phene of longer root hairs and the architectural phene of shallower basal root growth are synergetic for phosphorus acquisition.