Transcriptome analysis of Crossostephium chinensis provides insight into the molecular basis of salinity stress responses.

Haiyan Yang,Shuangji Lin,Yongjuan Yang,Tengxun Zhang,Yanhong Guo,Jingxing Zhang,Ming Sun,Debasis Chakrabarty

doi:10.1371/journal.pone.0187124

Abstract

Soil salinization is becoming a limitation to the utilization of ornamental plants worldwide. Crossostephium chinensis (Linnaeus) Makino is often cultivated along the southeast coast of China for its desirable ornamental qualities and high salt tolerance. However, little is known about the genomic background of the salt tolerance mechanism in C. chinensis. In the present study, we used Illumina paired-end sequencing to systematically investigate leaf transcriptomes derived from C. chinensis seedlings grown under normal conditions and under salt stress. A total of 105,473,004 bp of reads were assembled into 163,046 unigenes, of which 65,839 (40.38% of the total) and 54,342 (33.32% of the total) were aligned in Swiss-Prot and Nr protein, respectively. A total of 11,331 (6.95%) differentially expressed genes (DEGs) were identified among three comparisons, including 2,239 in ‘ST3 vs ST0’, 5,880 in ‘ST9 vs ST3’ and 9,718 in ‘ST9 vs ST0’, and they were generally classified into 26 Gene Ontology terms and 58 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway terms. Many genes encoding important transcription factors (e.g., WRKY, MYB, and AP2/EREBP) and proteins involved in starch and sucrose metabolism, arginine and proline metabolism, plant hormone signal transduction, amino acid biosynthesis, plant-pathogen interactions and carbohydrate metabolism, among others, were substantially up-regulated under salt stress. These genes represent important candidates for studying the salt-response mechanism and molecular biology of C. chinensis and its relatives. Our findings provide a genomic sequence resource for functional genetic assignments in C. chinensis. These transcriptome datasets will help elucidate the molecular mechanisms responsible for salt-stress tolerance in C. chinensis and facilitate the breeding of new stress-tolerant cultivars for high-saline areas using this valuable genetic resource.

Highlights

Soil salinization is a major global environmental problem
The former group includes various osmoprotectants, late-embryogenesis-abundant (LEA) proteins, aquaporin (APQ) proteins, chaperones, and antioxidant enzymes. The latter group primarily consists of transcription factors, such as NAC, WRKY, MYB, bZIP, ERF, and bHLH transcription factors, which are activated by a series of signal transduction pathways
The four physiological parameters of C. chinensis seedlings tended to differ in their variation under 0, 1, 3, 6, 9, 12, 24 and 72 hours of salt stress (Fig 1)

Summary

Introduction

Soil salinization is a major global environmental problem. Approximately one-third of the irrigated land worldwide has been affected by salinized soil, especially in arid and semi-arid regions [1, 2]. Plant salt-responsive genes can be classified into two groups, those that directly protect plants against environmental stresses and those that regulate the expression of downstream target genes in the stress response [9]. The former group includes various osmoprotectants, late-embryogenesis-abundant (LEA) proteins, aquaporin (APQ) proteins, chaperones, and antioxidant enzymes. The latter group primarily consists of transcription factors, such as NAC, WRKY, MYB, bZIP, ERF, and bHLH transcription factors, which are activated by a series of signal transduction pathways. The abscisic acid (ABA), Ca2+-dependent, SOS, and MAPK signaling pathways play important roles in the salt-response process [12,13,14,15]

Methods

Results

Discussion

Conclusion