MAPKs regulate root growth by influencing auxin signaling and cell cycle-related gene expression in cadmium-stressed rice

Abstract

This work aims to analyze the relationship between root growth, mitogen-activated protein kinase (MAPK), auxin signaling, and cell cycle-related gene expression in cadmium (Cd)-stressed rice. The role of MAPKs in auxin signal modification and cell cycle-related gene expression during root growth was investigated by disrupting MAPK signaling using the MAPKK inhibitor PD98059 (PD). Treatment with Cd caused a significant accumulation of Cd in the roots. A Cd-specific probe showed that Cd is mainly localized in the meristematic zone and vascular tissues. Perturbation of MAPK signaling using PD significantly suppressed root system growth under Cd stress. The transcription of six MAPK genes was inhibited by Cd compared to the control. Detection using DR5-GUS transgenic rice showed that the intensity and distribution pattern of GUS staining was similar in roots treated with PD or Cd, whereas in Cd plus PD-treated roots, the GUS staining pattern was similar to that of the control, which indicates a close association of MAPK signaling with auxin homeostasis under control and Cd stress conditions. The expression of most key genes of auxin signaling, including OsYUCCA, OsPIN, OsARF, and OsIAA, and of most cell cycle-related genes, was negatively regulated by MAPKs under Cd stress. These results suggest that the MAPK pathway plays specific roles in auxin signal transduction and in the control of the cell cycle in response to Cd stress. Altogether, MAPKs take part in the regulation of root growth via auxin signal variation and the modified expression of cell cycle-related genes in Cd-stressed rice. A working model for the function of MAPKs in rice root systems grown under Cd stress is proposed.

Cadmium-induced reactive oxygen species generation, changes in morphogenic responses and activity of some enzymes in barley root tip are regulated by auxin

“…Several observations suggest that alterations in the distribution of IAA in root apex are involved in the responses of roots to toxic concentrations of various metals. In rice primary root tips, a marked IAA accumulation was observed mainly in the root cap, in the elongation zone and in the vascular bundle after 6 h of Cd treatment (Zhao et al 2013). IAA accumulation in transition and elongation root zones has also been reported in Al-treated Arabidopsis root apex probably mediated by Al-induced enhanced ethylene synthesisevoked disruption of auxin polar transport .…”

Cross Talk between Nitric Oxide and Phytohormones Regulate Plant Development during Abiotic Stresses

“…Cd-induced increase in endogenous levels of NO is associated with its role as a bioactive molecule to quench ROS [54]. Alterations in hormonal homeostasis are potential signals that directly afect plant responses to Cd stress, including interplay between hormones and the whole plant signaling network, such as the ROS [55], MAPK [56], and NO signaling pathways [57]. Exposure to short-term Cd stress revealed an interrelation of ET with NO generation, polyamine metabolism, and MAPK cascades in young Glycine max seedlings [58].…”

Salix matsudana Koidz Tolerance Mechanisms to Cadmium: Uptake and Accumulation, Subcellular Distribution, and Chemical Forms

“…A Cdspecific probe was made by adding 50 μL of dimethyl sulfoxide to one vial of the dye. This stock solution was then diluted 1:10 with 0.85% NaCl [27]. The roots were immersed in diluted stock solution at 40ºC for 90 min in the dark.…”