Rice OsWRKY50 Mediates ABA-Dependent Seed Germination and Seedling Growth, and ABA-Independent Salt Stress Tolerance.
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ABSTRACT:
SUBMITTER: Huang S
PROVIDER: S-EPMC8395310 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BACKGROUNDMany transcription factors (TFs), such as those in the basic helix-loop-helix (bHLH) family, are important for regulating plant growth and plant responses to abiotic stress. The expression of OsbHLH035 is induced by drought and salinity. However, its functional role in rice growth, development, and the salt response is still unknown.RESULTSThe bHLH TF OsbHLH035 is a salt-induced gene that is primarily expressed in germinating seeds and seedlings. Stable expression of GFP-fused OsbHLH035 in rice transgenic plants revealed that this protein is predominantly localized to the nucleus. Osbhlh035 mutants show delayed seed germination, particularly under salt-stress conditions. In parallel, abscisic acid (ABA) contents are over-accumulated, and the expression of the ABA biosynthetic genes OsABA2 and OsAAO3 is upregulated; furthermore, compared with that in wild-type (WT) seedlings, the salt-induced expression of OsABA8ox1, an ABA catabolic gene, in germinating Osbhlh035 mutant seeds is downregulated. Moreover, Osbhlh035 mutant seedlings are unable to recover from salt-stress treatment. Consistently, sodium is over-accumulated in aerial tissues but slightly reduced in terrestrial tissues from Osbhlh035 seedlings after salt treatment. Additionally, the expression of the sodium transporters OsHKT1;3 and 1;5 is reduced in Osbhlh035 aerial and terrestrial tissues, respectively. Furthermore, genetic complementation can restore both the delayed seed germination and the impaired recovery of salt-treated Osbhlh035 seedlings to normal growth.CONCLUSIONOsbHLH035 mediates seed germination and seedling recovery after salt stress relief through the ABA-dependent and ABA-independent activation of OsHKT pathways, respectively.
| S-EPMC6134479 | biostudies-other
Project description:Alfalfa (Medicago sativa L.) is an important legume crop for forage, agriculture, and environment in the world. Ascorbic acid (AsA) plays positive roles in plants. However, its effects on germination and salt-tolerance of alfalfa are unknown. The effects of AsA applications on seed germination and seedling salt-tolerance of alfalfa were investigated. The results revealed that 0.1 and 1 mmol L-1 of exogenous AsA increased germination, amylase, and protease, as well as seedling length, fresh weight (FW), dry weight (DW), and endogenous AsA both in the shoots and roots, except that 1 mmol L-1 AsA reduced the activities of α-amylase, β-amylase and protease on day 3. However, 10 and 100 mmol L-1 AsA inhibited these parameters and even caused serious rot. It indicates that 0.1 mmol L-1 AsA has the optimal effects, whereas 100 mmol L-1 AsA has the worst impacts. Another part of the results showed that 0.1 mmol L-1 AsA not only enhanced stem elongation, FW and DW, but also increased chlorophyll and carotenoids both under non-stress and 150 mmol L-1 NaCl stress. Furthermore, 0.1 mmol L-1 AsA mitigated the damages of membrane permeability, malondialdehyde, and excessive reactive oxygen species (ROS) and ions both in the shoots and roots under 150 mmol L-1 NaCl stress. Hence, 0.1 mmol L-1 AsA improves growth and induces salt-tolerance by inhibiting excessive ROS, down-regulating the ion toxicity and up-regulating the antioxidant system. The principal component analysis included two main components both in the shoots and roots, and it explained the results well. In summary, the optimum concentration of 0.1 mmol L-1 AsA can be implemented to improve the seed germination and seedling growth of alfalfa under salt stress.
| S-EPMC8084155 | biostudies-literature
Project description:Rice is highly sensitive to salinity stress during the seedling establishment phase. Salt stress is widely occurring in cultivated areas and severely affects seed germination ability and seedling establishment, which may result in a complete crop failure. The objective of the present study is to identify quantitative trait loci (QTLs) related to salt tolerance of the germination and seedling stages in a rice backcross inbred line (BIL) population that was derived from a backcross of an Africa rice ACC9 as donor and indica cultivar Zhenshan97 (ZS97) as the recurrent parent. Under salt stress, ACC9 exhibited a higher germination percentage, but more repressed seedling growth than ZS97. Using the BIL population, 23 loci for germination parameters were detected at the germination stage and 46 loci were identified for several morphological and physiological parameters at the seedling stage. Among them, nine and 33 loci with the ACC9 alleles increased salt tolerance at the germination and seedling stages, respectively. Moreover, several major QTLs were found to be co-localized in the same or overlapping regions of previously reported genes for salt stress. These major loci will facilitate improving salt-tolerance rice in genome-breeding programs.
| S-EPMC7996262 | biostudies-literature
Project description:UDP-glycosyltransferases (UGTs) play key roles in modulating plant development and responses to environmental challenges. Previous research reported that the Arabidopsis UDP-glucosyltransferase 74E2 (AtUGT74E2), which transfers glucose to indole-3-butyric acid (IBA), is involved in regulating plant architecture and stress responses. Here, we show novel and distinct roles of UGT74E2 in rice. We found that overexpression of AtUGT74E2 in rice could enhance seed germination. This effect was also observed in the presence of IBA and abscisic acid (ABA), as well as salt and drought stresses. Further investigation indicated that the overexpression lines had lower levels of free IBA and ABA compared to wild-type plants. Auxin signaling pathway gene expression such as for OsARF and OsGH3 genes, as well as ABA signaling pathway genes OsABI3 and OsABI5, was substantially downregulated in germinating seeds of UGT74E2 overexpression lines. Consistently, due to reduced IBA and ABA levels, the established seedlings were less tolerant to drought and salt stresses. The regulation of rice seed germination and stress tolerance could be attributed to IBA and ABA level alterations, as well as modulation of the auxin/ABA signaling pathways by UGT74E2. The distinct roles of UGT74E2 in rice implied that complex and different molecular regulation networks exist between Arabidopsis and rice.
| S-EPMC7582762 | biostudies-literature
Project description:Rice yield is highly sensitive to increased temperature. Given the trend of increasing global temperatures, this sensitivity to higher temperatures poses a challenge for achieving global food security. Early seed development in rice is highly sensitive to unfavorable environmental conditions. Heat stress (HS) during this stage decreases seed size and fertility, thus reducing yield. Here, we explore the transgenerational phenotypic consequences of HS during early seed development on seed viability, germination, and establishment. To elucidate the impact of HS on the developmental events in post-zygotic rice seeds, we imposed moderate (35°C) and severe (39°C) HS treatments initiated 1 day after fertilization and maintained for 24, 48, or 72 h. The transient HS treatments altered the initiation of endosperm (ED) cellularization, seed size and/or the duration of spikelet ripening. Notably, seeds exposed to 24 and 48 h moderate HS exhibited higher germination rate compared to seeds derived from plants grown under control or severe HS. A short-term HS resulted in altered expression of Gibberellin (GA) and ABA biosynthesis genes during early seed development, and GA and ABA levels and starch content at maturity. The increased germination rate after 24 of moderate HS could be due to altered ABA sensitivity and/or increased starch level. Our findings on the impact of transient HS on hormone homeostasis provide an experimental framework to elucidate the underlying molecular and metabolic pathways.
| S-EPMC6290647 | biostudies-other
Project description:B12D belongs to a function unknown subgroup of the Balem (Barley aleurone and embryo) proteins. In our previous work on rice seed germination, we identified a B12D-like protein encoded by LOC_Os7g41350 (named OsB12D1). OsB12D1 pertains to an ancient protein family with an amino acid sequence highly conserved from moss to angiosperms. Among the six OsB12Ds, OsB12D1 is one of the major transcripts and is primarily expressed in germinating seed and root. Bioinformatics analyses indicated that OsB12D1 is an anoxic or submergence resistance-related gene. RT-PCR results showed OsB12D1 is induced remarkably in the coleoptiles or roots by flooding during seed germination and early seedling growth. The OsB12D1-overexpressed rice seeds could protrude radicles in 8 cm deep water, further exhibiting significant flooding tolerance compared to the wild type. Moreover, this tolerance was not affected by the gibberellin biosynthesis inhibitor paclobutrazol. OsB12D1 was identified in the mitochondrion by subcellular localization analysis and possibly enhances electron transport through mediating Fe and oxygen availability under flooded conditions. This work indicated that OsB12D1 is a promising gene that can help to enhance rice seedling establishment in farming practices, especially for direct seeding.
| S-EPMC4159805 | biostudies-other
Project description:BackgroundImproving the salt tolerance of direct-seeding rice at the seed germination stage is a major breeding goal in many Asian rice-growing countries, where seedlings must often establish in soils with a high salt content. Thus, it is important to understand the genetic mechanisms of salt tolerance in rice and to screen for germplasm with salt tolerance at the seed germination stage. Here, we investigated seven seed germination-related traits under control and salt-stress conditions and conducted a genome-wide association study based on the re-sequencing of 478 diverse rice accessions.ResultsThe analysis used a mixed linear model and was based on 6,361,920 single nucleotide polymorphisms in 478 rice accessions grouped into whole, indica, and non-indica panels. Eleven loci containing 22 significant salt tolerance-associated single nucleotide polymorphisms were identified based on the stress-susceptibility indices (SSIs) of vigor index (VI) and mean germination time (MGT). From the SSI of VI, six major loci were identified, explaining 20.2% of the phenotypic variation. From the SSI of MGT, five major loci were detected, explaining 26.4% of the phenotypic variation. Of these, seven loci on chromosomes 1, 5, 6, 11, and 12 were close to six previously identified quantitative gene loci/genes related to tolerance to salinity or other abiotic stresses. The strongest association region for the SSI of MGT was identified in a ~ 13.3 kb interval (15450039-15,463,330) on chromosome 1, near salt-tolerance quantitative trait loci controlling the Na+: K+ ratio, total Na+ uptake, and total K+ concentration. The strongest association region for the SSI of VI was detected in a ~ 164.2 kb interval (526662-690,854) on chromosome 2 harboring two nitrate transporter family genes (OsNRT2.1 and OsNRT2.2), which affect gene expression under salt stress. The haplotype analysis indicated that OsNRT2.2 was associated with subpopulation differentiation and its minor/rare tolerant haplotype was detected.ConclusionsThese results provide valuable information for salt tolerance-related gene cloning and for understanding the genetic mechanisms of salt tolerance at the seed germination stage. This information will be useful to improve the salt tolerance of direct-seeding rice varieties by genomic selection or marker-assisted selection.
| S-EPMC5450148 | biostudies-literature
Project description:Fatty acid desaturases play important role in plant responses to abiotic stresses. However, their exact function in plant resistance to salt stress is unknown. In this work, we provide the evidence that FAD2, an endoplasmic reticulum localized ?-6 desaturase, is required for salt tolerance in Arabidopsis. Using vacuolar and plasma membrane vesicles prepared from the leaves of wild-type (Col-0) and the loss-of-function Arabidopsis mutant, fad2, which lacks the functional FAD2, we examined the fatty acid composition and Na+-dependent H+ movements of the isolated vesicles. We observed that, when compared to Col-0, the level of vacuolar and plasma membrane polyunsaturation was lower, and the Na+/H+ exchange activity was reduced in vacuolar and plasma membrane vesicles isolated from fad2 mutant. Consistent with the reduced Na+/H+ exchange activity, fad2 accumulated more Na+ in the cytoplasm of root cells, and was more sensitive to salt stress during seed germination and early seedling growth, as indicated by CoroNa-Green staining, net Na+ efflux and salt tolerance analyses. Our results suggest that FAD2 mediated high-level vacuolar and plasma membrane fatty acid desaturation is essential for the proper function of membrane attached Na+/H+ exchangers, and thereby to maintain a low cytosolic Na+ concentration for salt tolerance during seed germination and early seedling growth in Arabidopsis.
| S-EPMC3261201 | biostudies-literature
Project description:Soybean is an important and staple oilseed crop worldwide. Salinity stress has adverse effects on soybean development periods, especially on seed germination and post-germinative growth. Improving seed germination and emergence will have positive effects under salt stress conditions on agricultural production. Here we report that NaCl delays soybean seed germination by negatively regulating gibberellin (GA) while positively mediating abscisic acid (ABA) biogenesis, which leads to a decrease in the GA/ABA ratio. This study suggests that fluridone (FLUN), an ABA biogenesis inhibitor, might be a potential plant growth regulator that can promote soybean seed germination under saline stress. Different soybean cultivars, which possessed distinct genetic backgrounds, showed a similar repressed phenotype during seed germination under exogenous NaCl application. Biochemical analysis revealed that NaCl treatment led to high MDA (malondialdehyde) level during germination and the post-germinative growth stages. Furthermore, catalase, superoxide dismutase, and peroxidase activities also changed after NaCl treatment. Subsequent quantitative Real-Time Polymerase Chain Reaction analysis showed that the transcription levels of ABA and GA biogenesis and signaling genes were altered after NaCl treatment. In line with this, phytohormone measurement also revealed that NaCl considerably down-regulated active GA1, GA3, and GA4 levels, whereas the ABA content was up-regulated; and therefore ratios, such as GA1/ABA, GA3/ABA, and GA4/ABA, are decreased. Consistent with the hormonal quantification, FLUN partially rescued the delayed-germination phenotype caused by NaCl-treatment. Altogether, these results demonstrate that NaCl stress inhibits soybean seed germination by decreasing the GA/ABA ratio, and that FLUN might be a potential plant growth regulator that could promote soybean seed germination under salinity stress.
| S-EPMC5554363 | biostudies-literature
Project description:DREB proteins are involved mainly in plant responses to abiotic stresses such as cold, drought or high salinity as well as ABA signalling. However, the function of most rice DREB genes and the underlying molecular mechanisms controlling these responses remains elusive. In this study, ARAG1, a rice DREB gene, was functionally analysed.Antisense and over-expression constructs of ARAG1 were introduced into rice by an Agrobacterium-mediated method. RT-PCR and western blot were used to detect ARAG1 accumulation in transgenics. PEG and ABA were used to test their response to abiotic stresses.ARAG1 was expressed in inflorescences, roots, immature embryos and germinating seeds, but not in coleoptiles, leaves or mature embryos. Drought stress and ABA treatment increased transcript levels of the gene rapidly. ARAG1 knockdown line was hypersensitive to ABA application during seed germination and seedling growth. However, the line over-expressing ARAG1 behaved similarly to wild type in these circumstances. Knockdown of ARAG1 weakened tolerance of the transgenic seedlings to drought stress, while over-expression of it increased the tolerance slightly. In addition, activity of alpha-amylases was enhanced in germinating seeds of the knockdown and over-expression lines.These results indicate that ARAG1 was involved in the ABA signalling and stress responsive pathways.
| S-EPMC2826253 | biostudies-literature