Transcriptomic insights into the molecular aspects of salt stress responses in Kandelia candel roots

Jianhong Xing ,Fang-Lin Tan ,Lingxia Wang ,Dezhuo Pan ,Wei Chen

doi:10.3906/bot-1909-11

Abstract

The mangrove plant Kandelia candel is a type of woody halophyte that grows in tropical and subtropical ocean intertidal zones and exhibits a high salt tolerance. In this study, 61,970 unigenes were obtained from the roots of 60-day-old K. candel seedlings treated with 0 (control), 200, 400, and 600 mM NaCl for 3 days with an N50 of 1510 bp. Moreover, 454, 311, and 2663 genes were differentially expressed under 200, 400, and 600 mM NaCl treatments, respectively. These differentially expressed genes were primarily involved in plant hormone signal transduction, carbohydrate and energy metabolism, amino acid metabolism, stress response, and defense. The levels of 12 important differentially expressed genes were confirmed by qRT-PCR, showing that the changing trend was generally consistent with the results of the transcriptomic analysis. In addition, physiological parameters involved in energy metabolism, amino acid metabolism, and the reactive oxygen species scavenging process were significantly increased under salt stress treatment, and the trend was consistent with the results of transcription and qRT-PCR. This study indicated that K. candel roots could tolerate high salt stress by enhancing ethylene signal transduction, maintaining a stable energy supply, increasing antioxidant capacity. Specially, we found that accumulation of ?-aminobutyric acid and glutamate, but not proline, might play an important role in salt tolerance in the roots of K. candel.

Highlights

In recent years, the problem of soil salinization has become increasingly prominent, which leads to the decline of land productivity and poses a major threat to the sustainable development of agriculture (Roy et al, 2014)
Previous studies have found that high salt stress could induce the expression of ACS5 and ACS7 genes in Arabidopsis thaliana (Wang et al, 2005) and upregulate the expression of NtACS1 gene in tobacco (Cao et al, 2006)
The results of RNA-Seq and Quantitative real time-PCR (qRT-PCR) both indicated that the SAMS2, ACS, ACO, and ERF114 genes which related to ethylene synthesis were significantly upregulated in the roots of K. candel under salt stress

Summary

Introduction

The problem of soil salinization has become increasingly prominent, which leads to the decline of land productivity and poses a major threat to the sustainable development of agriculture (Roy et al, 2014). It is worthwhile to investigate the salt tolerance mechanism of plants and identify salt-tolerant gene resources and address the intricate and serious problem of soil salinization. Woody salt-tolerant plants, grow in the intertidal coastal zone and are impregnated by seawater periodically. Such plants have developed a set of salt-tolerant mechanisms which differ from those of freshwater and terrestrial plants. Investigating the salt-tolerant mechanism of mangroves is desirable to achieve a better understanding of the salt-tolerant characteristics in woody plants, and

Methods

Results

Conclusion