Natural Variation of Arabidopsis Root Architecture Reveals Complementing Adaptive Strategies to Potassium Starvation      

Abstract

Root architecture is a highly plastic and environmentally responsive trait that enables plants to counteract nutrient scarcities with different foraging strategies. In potassium (K) deficiency (low K), seedlings of the Arabidopsis (Arabidopsis thaliana) reference accession Columbia (Col-0) show a strong reduction of lateral root elongation. To date, it is not clear whether this is a direct consequence of the lack of K as an osmoticum or a triggered response to maintain the growth of other organs under limiting conditions. In this study, we made use of natural variation within Arabidopsis to look for novel root architectural responses to low K. A comprehensive set of 14 differentially responding root parameters were quantified in K-starved and Kreplete plants. We identified a phenotypic gradient that links two extreme strategies of morphological adaptation to low K arising from a major tradeoff between main root (MR) and lateral root elongation. Accessions adopting strategy I (e.g. Col-0) maintained MR growth but compromised lateral root elongation, whereas strategy II genotypes (e.g. Catania-1) arrested MR elongation in favor of lateral branching. K resupply and histochemical staining resolved the temporal and spatial patterns of these responses. Quantitative trait locus analysis of K-dependent root architectures within a Col-0 3 Catania-1 recombinant inbred line population identified several loci each of which determined a particular subset of root architectural parameters. Our results indicate the existence of genomic hubs in the coordinated control of root growth in stress conditions and provide resources to facilitate the identification of the underlying genes.

Plasticity of the Arabidopsis Root System under Nutrient Deficiencies

“…Until now, a detailed examination of the effects of nutrient deficiencies on RSA has been fragmented or totally absent. In fact, only P, N, and, very recently, K deficiency-induced modifications of RSA were more exhaustively assessed in Arabidopsis (Linkohr et al, 2002;Sanchez-Calderon et al, 2005;Kellermeier et al, 2013). In other cases, although the effects of nutrient deficiencies on root development have been reported (for review, see López-Bucio et al, 2003;Nibau et al, 2008), these effects were either restricted to root hair formation (e.g.…”

Histone Deacetylase Complex1 Expression Level Titrates Plant Growth and Abscisic Acid Sensitivity in Arabidopsis

“…For the latter, seeds were germinated on agar plates and 2-to 3-week-old seedlings were placed in perforated lids of black 0.7-liter plastic containers. The growth medium consisted of a minimal sufficient nutrient medium (Kellermeier et al, 2013). For salt treatment, NaCl powder was stirred directly into the growth container to obtain the desired concentration (as stated in the figures).…”

Quantitative Variation in Responses to Root Spatial Constraint within Arabidopsis thaliana

“…We focused on the 0.5-cm root constraint, as this is the weakest treatment, suggesting that it should have the fewest indirect physiological effects, and as it also had a positive growth effect on the Bay accession. Furthermore, previous research has shown that the Bay and Sha parents and RILs have a root growth rate that would allow the seedlings' roots to grow below this constraint barrier within 24 h of germination (Loudet et al, 2005;Bouteillé et al, 2012;Kellermeier et al, 2013). Additionally, the soil within this constraint was packed to the same level as the surrounding soil and the constraint did not restrict the flow of water or oxygen given the surface-to-volume ratio.…”