The plasma membrane NADPH oxidase OsRbohA plays a crucial role in developmental regulation and drought‐stress response in rice

Abstract

Plasma membrane NADPH oxidases are major producers of reactive oxygen species (ROS) in plant cells under normal growth and stress conditions. In the present study the total activity of rice NADPH oxidases and the transcription of OsRbohA, which encodes an Oryza sativa plasma membrane NADPH oxidase, were stimulated by drought. OsRbohA was expressed in all tissues examined throughout development. Its mRNA was upregulated by a number of factors, including heat, drought, salt, oxidative stress and methyl jasmonate treatment. Compared with wild-type (WT), the OsRbohA-knockout mutant osrbohA exhibited upregulated expression of other respiratory burst oxidase homolog genes and multiple abnormal agronomic traits, including reduced biomass, low germination rate and decreased pollen viability and seed fertility. However, OsRbohA-overexpressing transgenic plants showed no differences in these traits compared with WT. Although osrbohA leaves and roots produced more ROS than WT, the mutant had lesser intracellular ROS. In contrast, OsRbohA-overexpressing transgenic plants exhibited higher ROS production at the intracellular level and in tissues. Ablation of OsRbohA impaired the tolerance of plants to various water stresses, whereas its overexpression enhanced the tolerance. In addition, a number of genes related to energy supply, substrate transport, stress response and transcriptional regulation were differentially expressed in osrbohA plants even under normal growth conditions, suggesting that OsRbohA has fundamental and broad functions in rice. These results indicate that OsRbohA-mediated processes are governed by complex signaling pathways that function during the developmental regulation and drought-stress response in rice.

The pathogenic development of Sclerotinia sclerotiorum in soybean requires specific host NADPH oxidases

“…However, ROS also act as important signalling molecules that communicate with phytohormone pathways, redox‐sensitive molecules and other ROS‐responsive processes to mediate acclimatization to various abiotic stresses (Bhattacharjee, ; Kaur et al ., ; Marino et al ., ). This is supported by results in rice (Wang et al ., ) and tomato (Li et al ., ), where osrbohA knockout and SlRBOHB ‐silenced plants, respectively, were found to be more sensitive to drought stress. We speculate that, under our experimental conditions, silencing of GmRBOH‐VI maintains ROS at sublethal levels without impeding signalling events, thus limiting the accumulation of excessive ROS during prolonged drought stress, which is detrimental to recovery and survivability.…”

“…The involvement of RBOH genes in abiotic stress responses is well documented (Cheng et al, 2013;Lin et al, 2009;Wang et al, 2013Wang et al, , 2016. Drought, in particular, is an important yieldlimiting stress in soybean production.…”

“…A role of RBOH genes in response to ROS-inducing insults has been reported, including in response to drought and salinity treatments (Cheng et al, 2013;Lin et al, 2009;Wang et al, 2013Wang et al, , 2016. Drought is an important yield-limiting stress in soybean production; therefore, we analysed the effect of GmRBOH-VI silencing under water stress conditions.…”

Structural complexity and functional diversity of plant NADPH oxidases

“…Further, we noticed the emergence of abiotic stress-related functions with biotic stress (pathogen/wound) and development-related Rbohs in cluster 4. For example, Z. mays ZmRbohB-α and ZmRbohB-β are involved in abiotic stress (Lin et al 2009a, b), O. sativa OsRbohA in drought and growth regulation (Wang et al 2016), OsRbohC in drought (Kaur and Pati 2016), H. vulgare HvRbohA and HvRbohFl in biotic stress from sub-cluster 4A (Yoshie et al 2005; Trujillo et al 2006; Lightfoot et al 2008). The sub-cluster 4B which contains Rbohs involved in biotic stress from Solanaceae family; L. esculentum LeRbohl, S. tuberosum StRbohA and N. benthamiana NbRbohA (Sagi et al 2004; Kumar et al 2007; Yoshioka et al 2003), while N. tabacum NtRbohF plays role in pollen tube growth (Potocky et al 2007).…”

The NAD kinase OsNADK1 affects the intracellular redox balance and enhances the tolerance of rice to drought

“…The expression profiles of OsNADK1 during different rice developmental stages and in tissues affected by different environmental factors were examined by real-time PCR (qRT-PCR) with OsActin1 and OsUBQ as the internal controls [77]. Total RNA was extracted from the tissues using RNAiso™ Plus reagent (Takara, Dalian, China) and then treated with RNase-free DNase I (Takara).…”