Transgenerational salinity tolerance plasticity in rice: Unraveling nongenetic phenotypic modifications and environmental influences.

Transgenerational plasticity in plants enables rapid adaptation to environmental changes, allowing organisms and their offspring to adapt to the environment without altering their underlying DNA. In this study, we investigated the plasticity of transgenerational salinity tolerance of rice plants using a reciprocal transplant experimental strategy. Our aim was to assess whether nongenetic environment-induced phenotypic modifications and transgenerational salinity affect the salinity tolerance of progeny while excluding nuclear genomic factors for two generations. Using salt-tolerant and salt-sensitive rice genotypes, we observed that the parentally salt-stressed salt-sensitive genotype displayed greater growth performance, photosynthetic activity, yield performance, and transcriptional responses than did the parentally nonstressed salt-sensitive plants under salt stress conditions. Surprisingly, salt stress-exposed salt-tolerant progeny did not exhibit as much salinity tolerance as salt stress-exposed salt-sensitive progeny under salt stress. Our findings indicate that the phenotypes of offspring plants differed based on the environment experienced by their ancestors, resulting in heritable transgenerational phenotypic modifications in salt-sensitive genotypes via maternal effects. These results elucidated the mechanisms underlying transgenerational plasticity in salinity tolerance, providing valuable insights into how plants respond to changing environmental conditions.

The Promising B-Type Response Regulator hst1 Gene Provides Multiple High Temperature and Drought Stress Tolerance in Rice.

High temperatures, drought, and salt stresses severely inhibit plant growth and production due to the effects of climate change. The Arabidopsis ARR1, ARR10, and ARR12 genes were identified as negative salt and drought stress regulators. However, in rice, the tolerance capacity of the hst1 gene, which is orthologous to the ARR1, ARR10, and ARR12 genes, to drought and multiple high temperature and drought stresses remains unknown. At the seedling and reproductive stages, we investigated the drought (DS) high temperature (HT) and multiple high temperature and drought stress (HT+DS) tolerance capacity of the YNU31-2-4 (YNU) genotype, which carries the hst1 gene, and its nearest genomic relative Sister Line (SL), which has a 99% identical genome without the hst1 gene. At the seedling stage, YNU demonstrated greater growth, photosynthesis, antioxidant enzyme activity, and decreased ROS accumulation under multiple HT+DS conditions. The YNU genotype also demonstrated improved yield potential and grain quality due to higher antioxidant enzyme activity and lower ROS generation throughout the reproductive stage under multiple HT+DS settings. Furthermore, for the first time, we discovered that the B-type response regulator hst1 gene controls ROS generation and antioxidant enzyme activities by regulating upstream and downstream genes to overcome yield reduction under multiple high temperatures and drought stress. This insight will help us to better understand the mechanisms of high temperature and drought stress tolerance in rice, as well as the evolution of tolerant crops that can survive increased salinity to provide food security during climate change.

The acquisition of impervious surface area from LANDSAT 8 satellite sensor data using urban indices: a comparative analysis.

Rapid and irregular urbanization is an essential issue in terms of environmental assessment and management. The dynamics of landscape patterns should be observed and analyzed by local authorities for a sustainable environment. The aim of this study is to determine which spectral urban index, originated from old Landsat missions, represents impervious area better when new generation Earth observation satellite Landsat 8 data are used. Two datasets of Landsat 8, acquired on 2 September 2013 and 10 September 2016, were utilized to investigate the consistency of the results. In this study, commonly used urban indices namely normalized difference built-up index (NDBI), index-based built-up index (IBI), urban index (UI), and enhanced built-up and bareness index (EBBI) were utilized to extract impervious areas. The accuracy assessment of urban indices was conducted by comparing the results with pan-sharpened images, which were classified using maximum likelihood classification (MLC) method. The kappa values of MLC, IBI, NDBI, EBBI, and UI for 2013 dataset were 0.89, 0.79, 0.71, 0.59, and 0.49, respectively, and the kappa values of MLC, IBI, NDBI, EBBI, and UI for 2016 dataset were 0.90, 0.78, 0.70, 0.56, and 0.47, respectively. In addition, area information was extracted from indices and classified images, and the obtained outcomes showed that IBI presented better results than the other urban indices, and UI extracted impervious areas worse than the other indices in both selected cases. Consequently, Landsat 8 satellite data can be considered as an important source to extract and monitor impervious surfaces for the sustainable development of cities.

Exogenous proline suppresses endogenous proline and proline-production genes but improves the salinity tolerance capacity of salt-sensitive rice by stimulating antioxidant mechanisms and photosynthesis.

Salinity is a critical environmental stress factor that significantly reduces crop productivity and yield. A mutant B-type response regulator gene (hst1) has been shown to promote salinity tolerance in the YNU genotype. Previous studies on the hst1 gene showed a higher proline production capacity under salt stress. Using almost identical genetic backgrounded salt-tolerant (YNU) and salt-sensitive (Sister line) rice genotypes, we tested the function of proline in the hst1 gene salinity-tolerance mechanism by applying exogenous proline under control and salt-stress conditions. Morpho-physiological, biochemical, and molecular analysis of ST and SS plants was performed to clarify the salinity tolerance mechanism mediated by the exogenous proline. The ST and SS genotypes accumulated exogenous proline, and the ST genotype has higher proline levels than the SS genotype. However, exogenous proline improved salt tolerance only in the SS genotype. Exogenous proline promotes plant and root growth by stimulating photosynthetic pigments and photosynthesis. The exogenous proline has a reductive effect on MDA, and H2O2 protects plants against ROS. Interestingly, exogenous proline lowers Na+ and raises K+ accumulations under salt stress. In the SS genotype, exogenous proline increases the activity of antioxidant enzymes (SOD, CAT, and APX) to protect against salinity-induced damage. The exogenous proline application down-regulates proline-synthesis genes (OsP5CS1 and OsP5CR) and up-regulates proline-degradation genes. Also, exogenous proline increases the expression of the OsSalT and OsGRAS29 genes, improving salinity tolerance in the SS genotype. Our study has demonstrated that proline plays a significant role in conferring salt tolerance with the salinity-tolerance-related hst1 mechanisms.

B-type response regulator hst1 controls salinity tolerance in rice by regulating transcription factors and antioxidant mechanisms.

Salinity is a serious environmental problem that limits plant yield in almost half of the agricultural fields. The hitomebore salt tolerant 1(hst1) is a mutant B-type response regulator gene that was reported to improve salinity tolerance in the 'YNU31-2-4' (YNU) genotype. The sister line (SL) is salt-sensitive, and the nearest genomic relative of the YNU plant has the OsRR22 gene, which is the non-mutant form of the hst1 gene. Biochemical and comprehensive transcriptome analysis of SL and YNU plants was performed to clarify the salinity tolerance mechanism(s) mediated by the hst1 gene. The hst1 gene reduced Na+ ions, lipid peroxidation, and H2O2 content, and improve proline and antioxidant enzymes activities under salt stress. Various transporter and gene-specific transcriptional regulator genes up-regulated in presence of the hst1 gene under saline conditions, identifying that post-stress transcription factors (OsbHLH056, OsH43, OsGRAS29, and OsMADS1) contributed to improved salinity tolerance in YNU plants. Specifically, OsSalT, miR156, and OsLPT1.16 genes were up-regulated, while upstream (OsHKs and OsHPs) and downstream regulators of the OsRR22 gene were down-regulated in YNU plants under saline conditions. Notably, the transcription factors reprogramming, upstream and downstream genes, indicate that these pathways are transcriptionally regulated by the hst1 gene. The findings of the regulatory role of the hst1 gene on plant transcriptome provide a greater understanding of hst1-mediated salt tolerance in rice plants. This knowledge will contribute to understanding the salinity tolerance mechanisms in rice and the evolution of salt-tolerant crops with the ability to withstand higher salinity to ensure food security during climate change.

Tolerance with High Yield Potential Is Provided by Lower Na+ Ion Accumulation and Higher Photosynthetic Activity in Tolerant YNU31-2-4 Rice Genotype under Salinity and Multiple Heat and Salinity Stress.

The yield-reduction effect of abiotic stressors such as salinity and heat stresses with the growing world population threatens food security. Although adverse effects of salinity and heat stress on plant growth and production parameters have been documented, in nature, abiotic stresses occur sequentially or simultaneously. In this study, the stress tolerance and yield capacity of Yukinkomai, YNU31-2-4, and YNU SL rice genotypes tested under control (26 °C, 0 mM NaCl), salinity (26 °C, 75 mM NaCl), heat (31 °C, 0 mM NaCl), and heat and salinity (31 °C, 75 mM NaCl) stress combinations at vegetative and reproductive stages with six different scenarios. The results show that salinity and the heat and salinity combination stresses highly reduce plant growth performance and yield capacity. Heat stress during reproduction does not affect the yield but reduces the grain quality. The YNU31-2-4 genotype performs better under heavy salt and heat and salinity stress then the Yukinkomai and YNU SL genotypes. YNU31-2-4 genotypes accumulate less Na+ and more K+ under salt and multiple stresses. In the YNU31-2-4 genotype, low Na+ ion accumulation increases photosynthetic activity and pigment deposition, boosting the yield. Stress lowers the glucose accumulation in dry seeds, but the YNU31-2-4 genotype has a higher glucose accumulation.

The TaGSK1, TaSRG, TaPTF1, and TaP5CS Gene Transcripts Confirm Salinity Tolerance by Increasing Proline Production in Wheat (Triticum aestivum L.).

Salinity is an abiotic stress factor that reduces yield and threatens food security in the world's arid and semi-arid regions. The development of salt-tolerant genotypes is critical for mitigating yield losses, and this journey begins with the identification of sensitive and tolerant plants. Numerous physiologic and molecular markers for detecting salt-tolerant wheat genotypes have been developed. One of them is proline, which has been used for a long time but has received little information about proline-related genes in wheat genotypes. In this study, proline content and the expression levels of proline-related genes (TaPTF1, TaDHN, TaSRG, TaSC, TaPIMP1, TaMIP, TaHKT1;4, TaGSK, TaP5CS, and TaMYB) were examined in sensitive, moderate, and tolerant genotypes under salt stress (0, 50, 150, and 250 mM NaCl) for 0, 12, and 24 h. Our results show that salt stress increased the proline content in all genotypes, but it was found higher in salt-tolerant genotypes than in moderate and sensitive genotypes. The salinity stress increased gene expression levels in salt-tolerant and moderate genotypes. While salt-stress exposure for 12 and 24 h had a substantial effect on gene expression in wheat, TaPTF1, TaPIMP1, TaMIP, TaHKT1;4, and TaMYB genes were considerably upregulated in 24 h. The salt-tolerant genotypes showed a higher positive interaction than a negative interaction. The TaPTF1, TaP5CS, TaGSK1, and TaSRG genes were found to be more selective than the other analyzed genes under salt-stress conditions. Despite each gene's specific function, increasing proline biosynthesis functioned as a common mechanism for separating salt tolerance from sensitivity.

Impact of Single and Combined Salinity and High-Temperature Stresses on Agro-Physiological, Biochemical, and Transcriptional Responses in Rice and Stress-Release.

Here, for the first time, we aimed to identify in rice the key mechanisms and processes underlying tolerance to high-temperature (HT) or salt stress (SS) alone, the co-occurrence of both stresses, and recovery using physiological and biochemical measurements and gene expression analysis. We also investigated whether recovery from the two stressors depended on the relative intensities/relief of each stressor. Wild type ('Yukinkomai') rice plants were found to be more susceptible to salinity or heat applied individually. SS leads to a depletion of cellular water content, higher accumulation of Na+, and alterations in photosynthetic pigments. The stress-tolerant cultivar 'YNU31-2-4' (YNU) displayed a lower Na+/K+ ratio, higher water content in cells and improved photosynthetic traits, antioxidant system, and expression of defence genes. Strikingly, the SS + HT combination provided a significant level of protection to rice plants from the effects of SS alone. The expression pattern of a selected set of genes showed a specific response and dedicated pathways in plants subjected to each of the different stresses, while other genes were explicitly activated when the stresses were combined. Aquaporin genes were activated by SS, while stress-related (P5CS, MSD1, HSPs, and ions transporters) genes were shaped by HT. Hierarchical clustering and principal component analyses showed that several traits exhibited a gradually aggravating effect as plants were exposed to the combined stresses and identified heat as a mitigating factor, clearly separating heat + salt-stressed from salt-non-heat-stressed plants. Furthermore, seedling recovery was far more dependent on the relative intensities of stressors and cultivars, demonstrating the influence of one stressor over another upon stress-release. Taken together, our data show the uniqueness and complexity of the physiological and molecular network modules used by rice plants to respond to single and combined stresses and recovery.

Development of new high-salt tolerant bread wheat (Triticum aestivum L.) genotypes and insight into the tolerance mechanisms.

The loss of cropland soils, climate change, and population growth are directly affecting the food supply. Given the higher incidence of salinity and extreme events, the cereal performance and yield are substantially hampered. Wheat is forecast to decline over the coming years due to the salinization widespread as one of the oldest and most environmental severe constraints facing global cereal production. To increase salinity tolerance of wheat, in this study, we developed two new salt-tolerant bread wheats, named 'Maycan' and 'Yildiz'. The salinity tolerance of these lines, their parents, and a salt-sensitive cultivar has been tested from measurements of physiological, biochemical, and genes associated with osmotic adjustment/plant tolerance in cultures containing 0 and 150 mM NaCl at the seedling stage. Differential growth reductions to increased salinity were observed in the salt-sensitive cultivar, with those newly developed exhibiting significantly greater root length, growth of shoot and water content as salinity tolerances overall than their parents. 'Maycan' and 'Yildiz' had higher osmoregulator proline content and antioxidants enzyme activities under salinity than the other bread wheat tested. Notably, an important upregulation in the expression of genes related to cellular ion balance, osmolytes accumulation, and abscisic acid was observed in both new wheat germplasms, which may improve salt tolerance. These finding revealed that 'Maycan' and 'Yildiz' exhibit high-salt tolerance at the seedling stage and differing in their tolerance mechanisms to the other tested cultivars, thereby providing an opportunity for their exploitation as modern bread wheats.

Optimized Nuclear Pellet Method for Extracting Next-Generation Sequencing Quality Genomic DNA from Fresh Leaf Tissue.

Next-generation sequencing (NGS) is a revolutionary advancement allowing large-scale discovery of functional molecular markers that has many applications, including plant breeding. High-quality genomic DNA (gDNA) is a prerequisite for successful NGS library preparation and sequencing; however, few reliable protocols to obtain such plant gDNA exist. A previously reported nuclear pellet (NP) method enables extraction of high-yielding gDNA from fresh leaf tissue of maize (Zea mays L.), but the quality does not meet the stringent requirements of NGS. In this study, we optimized the NP method for whole-genome sequencing of rice (Oryza sativa L.) through the integration of simple purification steps. The optimized NP method relied on initial nucleus enrichment, cell lysis, extraction, and subsequent gDNA purification buffers. The purification steps used proteinase K, RNase A, phenol/chloroform/isoamyl alcohol (25:24:1), and chloroform/isoamyl alcohol (24:1) treatments for protein digestion and RNA, protein, and phenol removal, respectively. Our data suggest that this optimized NP method allowed extraction of consistently high-yielding and high-quality undegraded gDNA without contamination by protein and RNA. Moreover, the extracted gDNA fulfilled the quality metrics of NGS library preparation for the Illumina HiSeq X Ten platform by the TruSeq DNA PCR-Free Library Prep Kit (Illumina). We provide a reliable step-by-step guide to the extraction of high-quality gDNA from fresh leaf tissues of rice for molecular biologists with limited resources.