Transcriptional Changes in the Developing Rice Seeds Under Salt Stress Suggest Targets for Manipulating Seed Quality

Abstract

Global sea-level rise, the effect of climate change, poses a serious threat to rice production owing to saltwater intrusion and the accompanying increase in salt concentration. The reclaimed lands, comprising 22.1% of rice production in Korea, now face the crisis of global sea-level rise and a continuous increase in salt concentration. Here, we investigated the relationship between the decrease in seed quality and the transcriptional changes that occur in the developing rice seeds under salt stress. Compared to cultivation on normal land, the japonica rice cultivar, Samgwang, grown on reclaimed land showed a greatly increased accumulation of minerals, including sodium, magnesium, potassium, and sulfur, in seeds and a reduced yield, delayed heading, decreased thousand grain weight, and decreased palatability and amylose content. Samgwang showed phenotypical sensitivity to salt stress in the developing seeds. Using RNA-seq technology, we therefore carried out a comparative transcriptome analysis of the developing seeds grown on reclaimed and normal lands. In the biological process category, gene ontology enrichment analysis revealed that the upregulated genes were closely associated with the metabolism of biomolecules, including amino acids, carboxylic acid, lignin, trehalose, polysaccharide, and chitin, and to stress responses. MapMan analysis revealed the involvement of upregulated genes in the biosynthetic pathways of abscisic acid and melatonin and the relationship of trehalose, raffinose, and maltose with osmotic stress. Interestingly, many seed storage protein genes encoding glutelins and prolamins were upregulated in the developing seeds under salt stress, indicating the negative effect of the increase of storage proteins on palatability. Transcription factors upregulated in the developing seeds under salt stress included, in particular, bHLH, MYB, zinc finger, and heat shock factor, which could act as potential targets for the manipulation of seed quality under salt stress. Our study aims to develop a useful reference for elucidating the relationship between seed response mechanisms and decreased seed quality under salt stress, providing potential strategies for the improvement of seed quality under salt stress.

Maternal Effects of Habitats Induce Stronger Salt Tolerance in Early-Stage Offspring of Glycyrrhiza uralensis from Salinized Habitats Compared with Those from Non-Salinized Habitats

“…Seed germination represents the initial stage in the life cycle of seed plants [25]. Climate change, improper fertilization, and irrigation tend to enhance soil salinity, posing new challenges to the seed germination and seedling development capacities of many land plants [26], including licorice.…”

Raffinose degradation-related gene GhAGAL3 was screened out responding to salinity stress through expression patterns of GhAGALs family genes

“…Studies have reported that the expression of genes related to RFO metabolites is significantly upregulated under stress conditions such as low temperature, drought, and high salt. These findings suggest that RFOs may have a crucial effect on enhancing resistance to abiotic stresses ( Joshi et al., 2021 ; Lee et al., 2021 ). In addition, studies have reported that RFOs can facilitate the elimination of reactive oxygen species (ROS) in plants experiencing stress ( Ma et al., 2021 ).…”

Climate–Nutrient–Crop Model: Novel Insights into Grain-Based Food Quality

“…60 One possible explanation is that 4 dS m −1 is too mild to trigger these effects. This assumption is supported by a paddy field experiment conducted on a reclaimed land using a "japonica" rice genotype, 61 which showed that even a minor increase in salinity from 4.00 to 4.17 dS m −1 can promote the upregulation of genes involved in the biosynthesis and accumulation of prolamin and glutelin.…”