Abstract
BackgroundSalt stress significantly restricts plant growth and production. Maize is an important food and economic crop but is also a salt sensitive crop. Identification of the genetic architecture controlling salt tolerance facilitates breeders to select salt tolerant lines. However, the critical quantitative trait loci (QTLs) responsible for the salt tolerance of field-grown maize plants are still unknown.ResultsTo map the main genetic factors contributing to salt tolerance in mature maize, a double haploid population (240 individuals) and 1317 single nucleotide polymorphism (SNP) markers were employed to produce a genetic linkage map covering 1462.05 cM. Plant height of mature maize cultivated in the saline field (SPH) and plant height-based salt tolerance index (ratio of plant height between saline and control fields, PHI) were used to evaluate salt tolerance of mature maize plants. A major QTL for SPH was detected on Chromosome 1 with the LOD score of 22.4, which explained 31.2% of the phenotypic variation. In addition, the major QTL conditioning PHI was also mapped at the same position on Chromosome 1, and two candidate genes involving in ion homeostasis were identified within the confidence interval of this QTL.ConclusionsThe detection of the major QTL in adult maize plant establishes the basis for the map-based cloning of genes associated with salt tolerance and provides a potential target for marker assisted selection in developing maize varieties with salt tolerance.
Highlights
Salt stress significantly restricts plant growth and production
We identified a major Quantitative trait locus (QTL) for salt tolerance in mature maize grown in a saline field using a permanent double haploid (DH) population and highdensity single nucleotide polymorphism (SNP) markers, and two candidate genes harbored in this QTL might be involved in the salt overly sensitive (SOS) pathway
The plant height of both PH6WC and PH4CV were significantly reduced by salt stress (Fig. 2a and b), the Salt tolerance index (PHI) of PH6WC was significantly higher than that of PH4CV, indicating that PH6WC is less sensitive to salt stress compared to PH4CV (Fig. 2c)
Summary
Salt stress significantly restricts plant growth and production. Salt stress causes ion and hyperosmotic imbalance in plants, which causes secondary oxidative damage. These changes occur at the molecular, cellular, and whole-plant levels, resulting in the. A major salt tolerance strategy in plant is to re-establish cellular ion homeostasis [4]. A high concentration of sodium ions (Na+) inhibits many key enzymes, so Na+ influx to the cell cytoplasm and organelles is sophisticatedly regulated. Vacuolar Na+/H+ antiporters manage the compartmental Na+ in the vacuole to prevent Na+ toxicity in cytosol, which has been shown as a strategy in many naturally salt tolerant plants (halophytes) [5]. In addition to the control of Na+ influx, Na+/H+ antiporters on the plasma membrane are important in exporting
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