Genetic variation for adventitious rooting in response to low phosphorus availability: potential utility for phosphorusacquisition from stratified soils

Abstract

We hypothesized that adventitious roots may improve crop adaptation to low-phosphorus soils by enhancing topsoil foraging. In a tropical field study, phosphorus stress stimulated adventitious rooting in two phosphorus-efficient genotypes of common bean (Phaseolus vulgaris L.) but not in two phosphorus-inefficient genotypes. Although phosphorus availability had no consistent effects on the length or biomass of whole root systems, it had differential effects on adventitious, basal, and taproots within root systems in a genotype-dependent manner, resulting in increased allocation to adventitious roots in efficient genotypes. Adventitious roots had greater length per unit biomass than other root types, especially under phosphorus stress. Adventitious roots had less construction cost than basal roots, despite having similar tissue nitrogen content. Phosphorus stress reduced lateral root density, and adventitious roots had less lateral root density than basal roots. Lateral roots formed further from the root tip in adventitious roots compared with basal roots, especially under phosphorus stress. Field results were confirmed in controlled environments in solid and liquid media. Stimulation of adventitious rooting by phosphorus stress tended to be greater in wild genotypes than in cultivated genotypes. We propose that adventitious rooting is a useful adaptation to low phosphorus availability, because adventitious roots explore topsoil horizons more efficiently than other root types.

Development of Common Bean (Phaseolus Vulgaris L.) Production Under Low Soil Phosphorus and Drought in Sub-Saharan Africa: A Review

“…The importance of root architectural traits in P acquisition has been investigated (Beebe et al, 2006;Liao et al, 2004;Miller et al, 2003). Miller et al (2003) reported that greater production of adventitious roots in common beans helps in P acquisition by improving plant foraging in the most P rich soil environment, while Beebe et al (2006) noted that basal root development and specific root length are responsible for efficient P acquisition.…”

“…Plant root architecture regulates the capacity of soil explored by roots, thereby playing a central role in P acquisition. Since P content and availability are more in top than in subsoil, root architectural traits that allow the exploration and use of P from surface layers govern P acquisition (Beebe et al, 2006;Liao et al, 2004;Miller et al, 2003). The P-efficient common bean genotypes which increase the below-ground biomass are able to acquire P in P-deficiency conditions (Liao et al, 2004;Namayanja, Semoka, Buruchara, Nchimbi, & Waswa, 2014).…”

“…Significant research and development efforts have always focused on overcoming the limitations of these production constraints, however, most of the efforts (Acosta-Díaz, Acosta-Gallegos, Trejo-López, Padilla-Ramírez, & Amador-Ramírez, 2009;Beebe et al, 2006;Cichy, Blair, Mendoza, Snapp, & Kelly, 2009;Manjeru, Madaanzi, Makeredza, Nciiza, & Sithole, 2007;Miller, Ochoa, Nielsen, Beck, & Lynch, 2003) address individual abiotic stress factors, with limited regard for the possible interactive effects under field conditions. The objective of this paper is, therefore, to scan and discuss existing research results and development information on common bean production, with attention being given to soil P deficiencies under drought conditions.…”

“…Tolerance to low soil P availability is associated with increased P acquisition efficiency, which is achieved by development of root architecture capable of foraging the nutrient (Beebe et al, 2006;Miller et al, 2003). Phosphorus acquisition efficiency is the ability of a plant to mobilise and absorb more P from the fertile soil layers (Atemkeng et al, 2011).…”

Development of a novel semi-hydroponic phenotyping system for studying root architecture

“…Quantifying the architecture of root systems is essential because crop productivity is almost always influenced by the availability and accessibility of water and nutrients that are heterogeneously distributed in the soil (Miller et al 2003;Cichy et al 2009;Gregory et al 2009). Root architecture directly impacts the capture of such soil resources and is, therefore, fundamental to crop productivity (Lynch 1995;Casson and Lindsey 2003;Malamy 2005;Watt et al 2006;Dunbabin 2007;Fita et al 2008;Gregory et al 2009).…”