Résultat de la recherche
A tightly regulated auxin signaling landscape is requiredfor spatial accommodation of lateral roots in Arabidopsis
In Arabidopsis thaliana, lateral root (LR) development requires spatial accommodation responses in overlying endodermal cells. This includes loss of cell volume whilst maintaining membrane integrity to allow the expansion of the underlying LR primordia(LRPs). These accommodation responses are regulated by auxin-mediated signaling, specifically through Aux/IAA proteins, involving IAA3/SHY2. Plants that express a stabilized version of SHY2 (shy2-2) in differentiated endodermal cells, CASP1pro::shy2-2 plants, fail to make LRs. Exogenous treatment with 1-naphthaleneacetic acid(NAA) was reported to partially restore LR formation in this spatial accommodation mutant. Using treatments with auxins having different transport properties, such asNAA, indole-3-acetic acid (IAA), and 2,4-dichlorophenoxyacetic acid (2,4-D), we assessed the ability of each auxin to rescue LR formation in CASP1 pro::shy2-2 roots. This revealed that IAA is the most effective in partially restoring LR development, NAA is effective in inducing LRPs but cannot maintain their canonical phenotype, whereas 2,4-D induces non-controlled cell divisions. In addition, we show that in CASP1pro::shy2-2 roots, AUX1 appears to be repressed in the zone where the oscillation of the auxin response has been described. Our study advances the understanding of auxin-regulated spatial accommodation mechanisms during LRP formation and highlights the complex interplay of auxin transport and signaling in bypassing the endodermal constraints.
The role of plant root systems in evolutionary adaptation
Roots provide a means to plants for gathering belowground resources. They are plastic and can adapt to ever-changing environmental cues. The plasticity of the roots comes from their ability to branch out by developing lateral and/or adventitious roots. In this chapter, we make an attempt to document the diversity in plant root systems and understand their role in evolutionary adaptation. After a brief introduction to different root systems, such as homorhizic and allorhizic ones, the relationship of plant roots with their surroundings, i.e., the rhizosphere and its effect on adaptation, will be discussed. Despite the difficulty to conclusively construct a timeline of evolution of plant root systems, documented facts from previous publications are examined and an effort has been made to delve into how rooting structures in plants adapted to prevailing conditions by bringing about endogenous changes vis-Ã -vis evolutionary development and exogenous changes to their surroundings.