Rice OsRH58, a chloroplast DEAD-box RNA helicase, improves salt or drought stress tolerance in Arabidopsis by affecting chloroplast translation

Ghazala Nawaz,Hunseung Kang

doi:10.1186/s12870-018-1623-8

Abstract

BackgroundDespite increasing characterization of DEAD-box RNA helicases (RHs) in chloroplast gene expression regulation at posttranscriptional levels in plants, their functional roles in growth responses of crops, including rice (Oryza sativa), to abiotic stresses are yet to be characterized. In this study, rice OsRH58 (LOC_Os01g73900), a chloroplast-localized DEAD-box RH, was characterized for its expression patterns upon stress treatment and its functional roles using transgenic Arabidopsis plants under normal and abiotic stress conditions.ResultsChloroplast localization of OsRH58 was confirmed by analyzing the expression of OsRH58-GFP fusion proteins in tobacco leaves. Expression of OsRH58 in rice was up-regulated by salt, drought, or heat stress, whereas its expression was decreased by cold, UV, or ABA treatment. The OsRH58-expressing Arabidopsis plants were taller and had more seeds than the wild type under favorable conditions. The transgenic plants displayed faster seed germination, better seedling growth, and a higher survival rate than the wild type under high salt or drought stress. Importantly, levels of several chloroplast proteins were increased in the transgenic plants under salt or dehydration stress. Notably, OsRH58 harbored RNA chaperone activity.ConclusionsThese findings suggest that the chloroplast-transported OsRH58 possessing RNA chaperone activity confers stress tolerance by increasing translation of chloroplast mRNAs.

Highlights

Despite increasing characterization of DEAD-box RNA helicases (RHs) in chloroplast gene expression regulation at posttranscriptional levels in plants, their functional roles in growth responses of crops, including rice (Oryza sativa), to abiotic stresses are yet to be characterized
To confirm whether OsRH58 is localized to chloroplasts, the Agrobacterium containing the OsRH58-GFP vector was infiltrated into tobacco leaves, and the transiently expressed OsRH58-GFP fusion proteins were observed using a confocal microscope
To analyze the stress-response expression patterns of OsRH58 in rice, different abiotic stresses were applied to rice seedlings, and OsRH58 levels were measured by quantitative RT-PCR analysis

Summary

Introduction

Despite increasing characterization of DEAD-box RNA helicases (RHs) in chloroplast gene expression regulation at posttranscriptional levels in plants, their functional roles in growth responses of crops, including rice (Oryza sativa), to abiotic stresses are yet to be characterized. Rice OsRH58 (LOC_Os01g73900), a chloroplast-localized DEAD-box RH, was characterized for its expression patterns upon stress treatment and its functional roles using transgenic Arabidopsis plants under normal and abiotic stress conditions. Plants are sessile organisms facing diverse environmental stresses, such as temperature shock, high salinity, drought, and UV. These stresses severely affect plant growth and productivity. Plants need to regulate cellular metabolic processes, including photosynthesis, that are crucial for plant growth and productivity under abiotic stresses [3, 4]. Inter-communications between the chloroplast and the nucleus via bidirectional signaling are required for fine-tuned gene expression in both organelles [8,9,10,11,12,13]

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Discussion

Conclusion