Morpho-physiological and proteomic responses to water stress in two contrasting tobacco varieties

Zheng Chen,Lin Wang,Zicheng Xu,Fazhan Wang,Jiayang Xu

doi:10.1038/s41598-019-54995-1

Abstract

To gain insight into the molecular mechanisms underpinning tobacco (Nicotiana tabacum) tolerance to drought stress, we integrated anatomical, physiological, and proteomic analyses of drought-tolerant (Yuyan6, [Y6]) and -sensitive (Yunyan87 [Y87]) varieties. In comparison to Y87, Y6 exhibited higher water retention capability, improved photosynthetic performance, delayed leaf-senescence, stable leaf ultrastructure, a stronger antioxidant defense, and lesser ROS accumulation when subjected to water stress. Using an iTRAQ-based proteomics approach, 405 and 1,560 differentially accumulated proteins (DAPs) were identified from Y6 and Y87 plants, respectively, of which 114 were found to be present in both cultivars. A subsequent functional characterization analysis revealed that these DAPs were significantly enriched in eight biological processes, six molecular functions, and six cellular components and displayed differential expression patterns in Y6 and Y87 plants, suggesting that the response to water stress between both varieties differed at the proteomic level. Furthermore, we constructed protein coexpression networks and identified hub proteins regulating tobacco defenses to water stress. Additionally, qPCR analysis indicated that the majority of genes encoding selected proteins showed consistency between mRNA levels and their corresponding protein expression levels. Our results provide new insights into the genetic regulatory mechanisms associated with drought response in tobacco plants.

Highlights

To gain insight into the molecular mechanisms underpinning tobacco (Nicotiana tabacum) tolerance to drought stress, we integrated anatomical, physiological, and proteomic analyses of drought-tolerant (Yuyan6, [Y6]) and -sensitive (Yunyan87 [Y87]) varieties
Leaf senescence is typically accompanied by a reduction in chlorophyll content, corroborated by the SPAD chlorophyll meter readings of leaf discs, which showed a 44% decrease in the chlorophyll content of Y87 plants on day 8, but only a 21% decrease in Y6 plants, when compared to their corresponding controls (Fig. 2L). These findings suggest that Y6 plants exhibited delayed leaf-senescence and improved water status compared to Y87 plants under water stress
We further examined the levels of abscisic acid (ABA)-related gene transcripts using qPCR, which revealed that, after polyethylene glycol (PEG)-induced water stress, Y6 plants had higher levels of NtNCED1 expression in relation to Y87 plants (Fig. 3F)

Summary

Introduction

To gain insight into the molecular mechanisms underpinning tobacco (Nicotiana tabacum) tolerance to drought stress, we integrated anatomical, physiological, and proteomic analyses of drought-tolerant (Yuyan6, [Y6]) and -sensitive (Yunyan87 [Y87]) varieties. Even though drought tolerance has proven difficult to define, as it is a multigenic trait that involves a large number of genes[19], a continuous effort to elucidate the molecular basis of drought tolerance is required in order to cultivate crops with enhanced water-use efficiency and to maintain environmental sustainability This is especially true when considering the elevated drought severity caused by climate anomalies and the uncertainty over future water supplies for an increasing global population. We performed an iTRAQ-based quantitative proteomics analysis to determine the responses of Yuyan[6] (Y6) and Yunyan[87] (Y87) cultivars to polyethylene glycol (PEG)-induced drought stress These results will help identify drought-resistant proteins among the differentially abundant proteins (DAPs) and provide new approaches for further molecular breeding of drought-resistant tobacco plants

Methods

Results

Discussion

Conclusion