Abstract
BackgroundSalinization is a primary abiotic stress constraining global plant growth and production. Weedy rice, though highly homologous to cultivated rice, is more salt tolerant during seed germination and seedling growth; we hypothesize that this is owing to ionic homeostasis and changes in the expression of genes encoding ion transport regulators.ResultsThe four different genotypes of weedy (JYGY-1 and JYFN-4) and cultivated (Nipponbare and 9311) rice have different salt-tolerance during seed germination and seedling vegetative growth under salt stress. In this study, Na+ and Ca2+content increased in weedy and cultivated rice genotypes under salt stress while K+ and Mg2+decreased; however, JYGY-1 had the lowest Na+/K+ ratio of assessed genotypes. Genes in the high-affinity K+ transporter (HKT) and tonoplast sodium-hydrogen exchanger (NHX) families, and salt overly sensitive 1 (OsSOS1) have more than 98% homology in amino acid sequences between weedy and cultivated rice genotypes. Under salt stress, the HKT family members were differentially expressed in the roots and shoots of four different genotypes. However, the NHX family transcripts were markedly up-regulated in all genotypes, but there are significant differences between different genotypes. OsSOS1 was significantly up-regulated in roots, especially in JYGY-1genotype.ConclusionsThe results showed that different genotypes had different germination and nutrient survival under salt stress, which was related to the difference of ion content and the difference of a series of ion transport gene expression. At the same time this study will provide new insight into the similarities and differences in ion homeostasis and gene regulatory mechanisms between weedy and cultivated rice under salt stress, which can aid in novel rice breeding and growth strategies.
Highlights
Salinization is a primary abiotic stress constraining global plant growth and production
The seed germination in Nipponbare, 9311, and JYGN-4 lines was inhibited by a 7–14 d treatment of 400 mM NaCl, while JYGY-1 seed was still able to germinate at this salt concentration (Fig. 2b, c)
The survival rates were rated as JYGY-1 > JYFN-4 > 9311 > Nipponbare, indicating that the weedy rice genotype JYGY-1 had the highest salt tolerance during both seed germination and seedling growth
Summary
Salinization is a primary abiotic stress constraining global plant growth and production. Salt stress is one of the most serious abiotic stresses that affects plant natural productivity and causes significant crop loss worldwide. One of the many important physiological changes during early plant cell evolution was the ability to adapt to low levels of Na+ and K+ intermediates. Leaves that develop photosynthesis and other metabolic processes are the main sites of Na+ toxicity [3]. Some mechanisms to alleviate Na+ toxicity in leaves have been discovered and/or proposed in rice.
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