New Paradigms in Brassinosteroids, Strigolactones, Sphingolipids, and Nitric Oxide Interaction in the Control of Lateral and Adventitious Root Formation

Abstract

The root system is formed by the primary root (PR), which forms lateral roots (LRs) and, in some cases, adventitious roots (ARs), which in turn may produce their own LRs. The formation of ARs is also essential for vegetative propagation in planta and in vitro and for breeding programs. Root formation and branching is coordinated by a complex developmental network, which maximizes the plant’s ability to cope with abiotic stress. Rooting is also a response caused in a cutting by wounding and disconnection from the donor plant. Brassinosteroids (BRs) are steroid molecules perceived at the cell surface. They act as plant-growth-regulators (PGRs) and modulate plant development to provide stress tolerance. BRs and auxins control the formation of LRs and ARs. The auxin/BR interaction involves other PGRs and compounds, such as nitric oxide (NO), strigolactones (SLs), and sphingolipids (SPLs). The roles of these interactions in root formation and plasticity are still to be discovered. SLs are carotenoid derived PGRs. SLs enhance/reduce LR/AR formation depending on species and culture conditions. These PGRs possibly crosstalk with BRs. SPLs form domains with sterols within cellular membranes. Both SLs and SPLs participate in plant development and stress responses. SPLs are determinant for auxin cell-trafficking, which is essential for the formation of LRs/ARs in planta and in in vitro systems. Although little is known about the transport, trafficking, and signaling of SPLs, they seem to interact with BRs and SLs in regulating root-system growth. Here, we review the literature on BRs as modulators of LR and AR formation, as well as their crosstalk with SLs and SPLs through NO signaling. Knowledge on the control of rooting by these non-classical PGRs can help in improving crop productivity and enhancing AR-response from cuttings.

Nitric oxide promotes adventitious root formation in cucumber under cadmium stress through improving antioxidant system, regulating glycolysis pathway and polyamine homeostasis

“…Several reports suggested that the endogenous NO accumulation has been implicated as being responsible for the development of adventitious root in plants ( Kang et al., 2018 ; Altamura et al., 2023 ). Compared to CK treatment, Cd stress significantly decreased endogenous NO levels during adventitious root development ( Figure 3 ), implying that Cd stress might lead to a significant reduction of adventitious root formation through inhibiting endogenous NO production.…”

Sphingomonas sediminicola Dae20 Is a Highly Promising Beneficial Bacteria for Crop Biostimulation Due to Its Positive Effects on Plant Growth and Development

“…The effect of S. sediminicola Dae20 on the root system, characterized by a strong increase in branching and root hairs, is closely related to its ability to influence the hormonal balance of the plant, either through the direct production of auxin in the form of IAA, through the modulation of ethylene levels, or through the production of nitric oxide. Indeed, these molecules are encoded by genes present in the genome of the bacteria [ 20 ] and they are known to influence these processes in plants [ 46 , 47 , 48 ]. Several species of Sphingomonas have been described with these abilities, such as S. LK11 , S. paucimobilis , S. pokkalii [ 18 , 49 , 50 , 51 , 52 , 53 , 54 ].…”

Abiotic Stress in Crop Production

“…It is not surprising that the phytohormones within this group show agonistic and synergistic properties with each other. Well-known examples are the positive effects of JA, SL, and BR on ABA [ 371 , 372 , 373 ] or interactions between BR and AUX [ 374 ]. Interestingly, melatonin has been shown to have a positive effect on stress resistance in various crops but it reportedly decreases the level of ABA, a process that is conserved across the different abiotic stresses [ 375 ].…”