MAP65-1a positively regulates H2O2 amplification and enhances brassinosteroid-induced antioxidant defence in maize

Abstract

Brassinosteroid (BR)-induced antioxidant defence has been shown to enhance stress tolerance. In this study, the role of the maize 65kDa microtubule-associated protein (MAP65), ZmMAP65-1a, in BR-induced antioxidant defence was investigated. Treatment with BR increased the expression of ZmMAP65-1a in maize (Zea mays) leaves and mesophyll protoplasts. Transient expression and RNA interference silencing of ZmMAP65-1a in mesophyll protoplasts further revealed that ZmMAP65-1a is required for the BR-induced increase in expression and activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Both exogenous and BR-induced endogenous H2O2 increased the expression of ZmMAP65-1a. Conversely, transient expression of ZmMAP65-1a in maize mesophyll protoplasts enhanced BR-induced H2O2 accumulation, while transient silencing of ZmMAP65-1a blocked the BR-induced expression of NADPH oxidase genes and inhibited BR-induced H2O2 accumulation. Inhibiting the activity and gene expression of ZmMPK5 significantly prevented the BR-induced expression of ZmMAP65-1a. Likewise, transient expression of ZmMPK5 enhanced BR-induced activities of the antioxidant defence enzymes SOD and APX in a ZmMAP65- 1a-dependent manner. ZmMPK5 directly interacted with ZmMAP65-1a in vivo and phosphorylated ZmMAP65-1a in vitro. These results suggest that BR-induced antioxidant defence in maize operates through the interaction of ZmMPK5 with ZmMAP65-1a. Furthermore, ZmMAP65-1a functions in H2O2 self-propagation via regulation of the expression of NADPH oxidase genes in BR signalling.

PP2A and microtubules function in 5‐aminolevulinic acid‐mediated H2O2 signaling in Arabidopsis guard cells

“…For instance, both ROS‐induced microtubule depolymerization (Yao et al ) and MTs‐resulted ROS accumulation (Wang et al ) were reported in the previous studies. In addition, Zhu et al () demonstrated a positive H 2 O 2 amplification loop regulated by MAP65, a microtubule‐associated protein. However, no information is available on the relationship between ROS and MTs in guard cells.…”

Role of Reactive Oxygen Species during Cell Expansion in Leaves

“…ANPs are required during cytokinesis, but also regulate pavement cell expansion, since anp2anp3 mutants show aberrant epidermal cell morphology (Beck et al, 2010). Notably, downstream the MAPK cascade act two conserved key regulators of cortical MT array organization, the microtubule-associated proteins MAP65-1 and MAP65-2, which both have been implicated in ROS responses (Lucas et al, 2011;Zhu et al, 2013;Livanos et al, 2012). Potentially, H 2 O 2 sensed by the ANP cascade modulates cytoskeleton dynamics during cell proliferation and expansion (Fig.…”

The interplay between ROS and tubulin cytoskeleton in plants

“…ZmMAP65-1a that was found to be increased after application of hydrogen peroxide was also shown to regulate hydrogen peroxide amplification upon treatment of Zea mays leaves with brassinosteroid phytohormones. 33 The ROSresponsive ZmMPK5 interacts with ZmMAP65-1a toward activating the expression of NADPH oxidase genes and the subsequent responses. 33 In particular, the transcription of several antioxidant defense genes, which is initiated after NADPH oxidase activation, requires the phosphorylation of ZmMAP65-1a by ZmMPK5.…”

“…33 The ROSresponsive ZmMPK5 interacts with ZmMAP65-1a toward activating the expression of NADPH oxidase genes and the subsequent responses. 33 In particular, the transcription of several antioxidant defense genes, which is initiated after NADPH oxidase activation, requires the phosphorylation of ZmMAP65-1a by ZmMPK5. 33,34 Therefore, it is very interesting that, during stress, cytoskeletal proteins respond to elevated ROS levels and at the same time activate the NADPH oxidase assisting the purposeful production of ROS.…”

“…In this direction, ZmMPK5 is activated by abscisic acid 44 and concurrently, as it was previously noticed, interacts with ZmMAP65-1a toward ROS production after treatment with brassinosteroids. 33 Abscisic acid also strongly modifies the levels of α and β tubulin mRNA transcripts 45 and induces depolymerization and reorganization of cortical MTs. 46,47 In addition, it is known that the rest classes of phytohormones also modulate ROS levels in plants, 9 whereas almost all the hormones interfere with plant cytoskeleton.…”