Understanding of Adventitious Root Formation: What Can We Learn From Comparative Genetics?

Abstract

Adventitious root (AR) formation is a complex developmental process controlled by a plethora of endogenous and environmental factors. Based on fossil evidence and genomic phylogeny, AR formation might be considered the default state of plant roots, which likely evolved independently several times. The application of next-generation sequencing techniques and bioinformatics analyses to non-model plants provide novel approaches to identify genes putatively involved in AR formation in multiple species. Recent results uncovered that the regulation of shoot-borne AR formation in monocots is an adaptive response to nutrient and water deficiency that enhances topsoil foraging and improves plant performance. A hierarchy of transcription factors required for AR initiation has been identified from genetic studies, and recent results highlighted the key involvement of additional regulation through microRNAs. Here, we discuss our current understanding of AR formation in response to specific environmental stresses, such as nutrient deficiency, drought or waterlogging, aimed at providing evidence for the integration of the hormone crosstalk required for the activation of root competent cells within adult tissues from which the ARs develop.

An auxin‐mediated regulatory framework for wound‐induced adventitious root formation in tomato shoot explants

“…Adventitious roots (ARs) develop post‐embryonically from non‐root tissues, such as stems and leaves, usually in response to challenging environmental conditions; they may also be induced by mechanical damage or during in vitro tissue culture (Bellini, Pacurar, & Perrone, 2014; Druege et al, 2019; Gonin, Bergougnoux, Nguyen, Gantet, & Champion, 2019). During normal development though, many plant species develop ARs to perform specialized functions, such as increasing soil foraging and water absorption (Mhimdi and Pérez‐Pérez, 2020). AR formation involves several developmental stages (de Klerk, van der Krieken, & de Jong, 1999), and the key regulatory events occurring during the induction phase result in the molecular reprogramming of some vascular‐associated cells (Lakehal & Bellini, 2019).…”

Tissue-specific metabolic reprogramming during wound inducedde novoorgan formation in tomato hypocotyl explants

“…We found striking patterns of ROS accumulation in the apical and basal region of the hypocotyl during the studied time-course, which was not directly correlated with the extent of cell death (this work), and hence might have a signaling role in de novo organ formation. ROS accumulation in the basal region of the hypocotyl explants at T4 and T8 might be related to AR emergence (Mhimdi and Pérez-Pérez, 2020). Indeed, during primary root (PR) and lateral root (LR) development in Arabidopsis thaliana , ROS distribution (which is regulated by specific POX enzymes) is required for transition between proliferating and differentiating cells in the meristem (Tsukagoshi et al, 2010; Fernández-Marcos et al, 2017).…”

Waterlogging stress induces antioxidant defense responses and aerenchyma formation and alters metabolisms of banana plants

“…Adventitious roots and aerenchyma are critical to improving the waterlogging tolerance in plants [27]. Waterlogged soils cause ethylene entrapment and affect auxin transportation, triggering the formation of adventitious roots [28]. The formation of aerenchyma is essential in plant waterlogging tolerance as it can provide oxygen to the submerged organs of a plant.…”