Deep Phenotyping of Coarse Root Architecture in R. pseudoacacia Reveals That Tree Root System Plasticity Is Confined within Its Architectural Model

Abstract

This study aims at assessing the influence of slope angle and multi-directional flexing and their interaction on the root architecture of Robinia pseudoacacia seedlings, with a particular focus on architectural model and trait plasticity. 36 trees were grown from seed in containers inclined at 0° (control) or 45° (slope) in a glasshouse. The shoots of half the plants were gently flexed for 5 minutes a day. After 6 months, root systems were excavated and digitized in 3D, and biomass measured. Over 100 root architectural traits were determined. Both slope and flexing increased significantly plant size. Non-flexed trees on 45° slopes developed shallow roots which were largely aligned perpendicular to the slope. Compared to the controls, flexed trees on 0° slopes possessed a shorter and thicker taproot held in place by regularly distributed long and thin lateral roots. Flexed trees on the 45° slope also developed a thick vertically aligned taproot, with more volume allocated to upslope surface lateral roots, due to the greater soil volume uphill. We show that there is an inherent root system architectural model, but that a certain number of traits are highly plastic. This plasticity will permit root architectural design to be modified depending on external mechanical signals perceived by young trees.

Root structure and biomass partitioning in tilted plants from twisted- and straight-stemmed populations of Pinus pinaster Ait

“…Rocks or flooding areas may also limit the lateral extension of the roots. Given the need for good anchorage, the root system must be able to adjust to the limitations imposed by the soil and develop the most efficient structure according to the particular conditions at each site (Danjon et al 2005(Danjon et al , 2013. Therefore, trade-offs can be expected between size variables (length, diameter) and shape variables (taper, winding, branching) of the taproot and second-order roots to form the most effective root system for the particular conditions of each site.…”

“…Mechanical stresses such as wind are known to increase root development (Cucchi et al 2004;Richter et al 2009;Danjon et al 2013), most likely at the expense of the aboveground part of the plant, which is seriously limited by the action of the wind, even if the wind is not of high intensity (Moulia et al 2011). Artificial flexing of low intensity also results in major changes in the structure of stem and roots (Danjon et al 2013).…”

Métodos De Avaliação Da Influência E Contribuição Das Plantas Sobre a Estabilidade De Taludes

“…Para os solos existem métodos padronizados de avaliação dos parâmetros de resistência (coesão e ângulo de atrito interno), obtidos normalmente por testes de resistência ao cisalhamento direto ou triaxial (LAMBE; WHITMAN, 1969). Para as plantas são considerados principalmente os valores de resistência à tração (DE BAETS et al, 2008), obtidos por métodos ainda não padronizados e que envolvem uma série de simplificações. Por essas razões, considerar a interação entre solo e raízes em análises de estabilidade de taludes, além de determinações realizadas in situ, pode envolver o uso de modelos simplificados e estimativas.…”

Root System Markup Language: Toward a Unified Root Architecture Description Language

“…While precise root system architecture characterization methods have been studied in woody plants for many years (Danjon et al, 1999(Danjon et al, , 2013Danjon and Reubens, 2007), physiological studies on smaller plants (e.g. Arabidopsis [Arabidopsis thaliana]) have often neglected detailed root architecture, using mainly global estimators, such as total root length or the maximal depth of the root system convex hull (Galkovskyi et al, 2012).…”

“…1A,II and III). In addition, while root system analysis is classically performed on two-dimensional (2D) images of root projections, recent years have seen the development of three-dimensional (3D) acquisition devices (Danjon et al, 1999(Danjon et al, , 2013Danjon and Reubens, 2007;Iyer-Pascuzzi et al, 2010;Clark et al, 2011;Mooney et al, 2012), which solve the issues of object occlusion yet increase the complexity of the root system description (Fig. 1B).…”