Abstract
Salt stress affects crop yield by limiting growth and delaying development. In this study, we constructed 16 transcriptome libraries from maize seedling roots using two maize lines, with contrasting salt tolerance, that were exposed to salt stress for 0, 6, 18 and 36 h. In total, 6,584 differential expression genes (DEGs; 3,669 upregulated, 2,915 downregulated) were induced in the salt-sensitive line and 6,419 DEGs (3,876 upregulated, 2,543 downregulated) were induced in the salt-tolerant line. Several DEGs common to both lines were enriched in the ABA signaling pathway, which was presumed to coordinate the process of maize salt response. A total of 459 DEGs were specifically induced in the salt-tolerant line and represented candidate genes responsible for high salt-tolerance. Expression pattern analysis for these DEGs indicated that the period between 0 and 6 h was a crucial period for the rapid response of the tolerant genes under salt stress. Among these DEGs, several genes, Aux/IAA, SAUR, and CBL-interacting kinase have been reported to regulate salt tolerance. In addition, the transcription factors WRKY, bZIP and MYB acted as regulators in the salt-responsive regulatory network of maize roots. Our findings will contribute to understanding of the mechanism on salt response and provide references for functional gene revelation in plants.
Highlights
Soil salinity stress is one of the most important abiotic stresses because it constrains global crop productivity (Ismail & Horie, 2017; Zhang et al, 2019a) by causing the retardation of plant growth and dysregulate various biological processes in plant (Fortmeier & Schubert, 2006; Fricke et al, 2004; Zhang et al, 2018)
The salt tolerance index (STI) values were 0.56 and 0.27 for L2010-3 and BML1234, respectively. These findings indicated that L2010-3 is more tolerant to salt stress than BML1234
Zm00001d018178 was significantly enriched in the terms ‘‘response to salt stress’’ (GO:0009651) and ‘‘abscisic acid-activated signaling pathway’’ (GO:0009738)
Summary
Soil salinity stress is one of the most important abiotic stresses because it constrains global crop productivity (Ismail & Horie, 2017; Zhang et al, 2019a) by causing the retardation of plant growth and dysregulate various biological processes in plant (Fortmeier & Schubert, 2006; Fricke et al, 2004; Zhang et al, 2018). SOS3 is an EF-hand calcium-binding protein that presumably senses calcium signal elicited by the salt stress (Halfter, Ishitani & Zhu, 2000; Zhu, 2002). In this pathway, the protein kinase complex SOS3-SOS2 is activated, which subsequently switch on the activity of ion transporter SOS1 by phosphorylation during salt stress (Quintero et al, 2011). Under salt stress, high affinity K+ transporter enhances salt tolerance in plants by maintaining Na+/K+ homeostasis (Cao et al, 2019; Zhang et al, 2018; Zhang et al, 2019a)
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