Global Reprogramming of Transcription in Chinese Fir (Cunninghamia lanceolata) during Progressive Drought Stress and after Rewatering.

Ruiyang Hu,Yuhan Sun,Xinjie Wang,Jinxing Wang,Yun Li,Dehuo Hu,Yue Zhang,Bo Wu,Hongjing Duan,Huiquan Zheng

doi:10.3390/ijms160715194

Ruiyang Hu, Yuhan Sun + Show 8 more

Open Access

https://doi.org/10.3390/ijms160715194

Copy DOI

Abstract

Chinese fir (Cunninghamia lanceolata), an evergreen conifer, is the most commonly grown afforestation species in southeast China due to its rapid growth and good wood qualities. To gain a better understanding of the drought-signalling pathway and the molecular metabolic reactions involved in the drought response, we performed a genome-wide transcription analysis using RNA sequence data. In this study, Chinese fir plantlets were subjected to progressively prolonged drought stress, up to 15 d, followed by rewatering under controlled environmental conditions. Based on observed morphological changes, plantlets experienced mild, moderate, or severe water stress before rehydration. Transcriptome analysis of plantlets, representing control and mild, moderate, and severe drought-stress treatments, and the rewatered plantlets, identified several thousand genes whose expression was altered in response to drought stress. Many genes whose expression was tightly coupled to the levels of drought stress were identified, suggesting involvement in Chinese fir drought adaptation responses. These genes were associated with transcription factors, signal transport, stress kinases, phytohormone signalling, and defence/stress response. The present study provides the most comprehensive transcriptome resource and the first dynamic transcriptome profiles of Chinese fir under drought stress. The drought-responsive genes identified in this study could provide further information for understanding the mechanisms of drought tolerance in Chinese fir.

Highlights

The natural environment for plants is composed of a complex set of abiotic and biotic stresses.Drought stress is an abiotic stress and it is one of the main factors that affects tree growth, vitality, and survival [1,2,3,4,5]
Based on three representative phenotypic characteristics that result from withdrawal of water, we defined the following three levels of drought stress (Figure S1): Mild stress (5-days water deficit) in which the colour of a few stem tip needles becomes light green and they dry up; moderate stress (10-days water deficit) in which the surface of the top needle shrinks and loses elasticity; and severe stress (15-days water deficit) in which most of the needles become curly and folded
In our study of the transcriptome of Chinese fir (2n = 22), approximately 37.2 GB of data were generated and assembled into 75,412 unigenes. Such a large number of reads (371,387,986 raw reads) produced considerably longer unigenes than those in other research involving Chinese fir; e.g., two studies that performed cambial activity transcriptome sequencing and reported average unigene lengths of 497 and 505 bp [43,44]. This increased transcriptome coverage depth would help to enhance the accuracy of the sequencing and ensure the accurate assembly

Summary

Introduction

Drought stress is an abiotic stress and it is one of the main factors that affects tree growth, vitality, and survival [1,2,3,4,5]. This is the case in arid and semiarid regions. Drought stress of plants induces a range of physiological and biochemical responses at the cellular and whole-organism levels. These responses include stomatal closure, repression of cell growth and photosynthesis, and activation of respiration [11,12]. Plants respond and adapt to water deficit at both the cellular and molecular levels, for example, by the accumulation of osmolytes and proteins involved in stress tolerance [13]

Objectives

Results

Conclusion