Salt Tolerance In Maize Research Articles

Salinity stress tolerance prediction for biomass-related traits in maize (Zea mays L.) using genome-wide markers.

Maize (Zea mays L.) is the third most important cereal crop after rice (Oryza sativa) and wheat (Triticum aestivum). Salinity stress significantly affects vegetative biomass and grain yield and, therefore, reduces the food and silage productivity of maize. Selecting salt-tolerant genotypes is a cumbersome and time-consuming process that requires meticulous phenotyping. To predict salt tolerance in maize, we estimated breeding values for four biomass-related traits, including shoot length, shoot weight, root length, and root weight under salt-stressed and controlled conditions. A five-fold cross-validation method was used to select the best model among genomic best linear unbiased prediction (GBLUP), ridge-regression BLUP(rrBLUP), extendedGBLUP, Bayesian Lasso, Bayesian ridge regression, BayesA, BayesB, and BayesC. Examination of the effect of different marker densities on prediction accuracy revealed that a set of low-density single nucleotide polymorphisms obtained through filtering based on a combination of analysis of variance and linkage disequilibrium provided the best prediction accuracy for all the traits. The average prediction accuracy in cross-validations ranged from 0.46 to 0.77 across the four derived traits. The GBLUP, rrBLUP, and all Bayesian models except BayesB demonstrated comparable levels of prediction accuracy that were superior to the other modeling approaches. These findings provide a roadmap for the deployment and optimization of genomic selection in breeding for salt tolerance in maize.

Effects of brassinolide on the physiological characteristics of maize (Zea Mays L.) Cultivars Under salt stress.

Effects of brassinolide on the physiological characteristics of maize under salt stress were investigated. Effect of exogenous application of brassinolide on the antioxidant system, endogenous hormone levels, sodium and potassium ion contents of the plants were measured in a salt-tolerant maize cultivar, Xianyu 335, and a salt-sensitive maize cultivar, Dongnong 253. Brassinolide induced better alleviation of physiological damage in different salt-sensitive maize cultivars under salt stress treatment. Exogenous administration of brassinolide was found to increase the antioxidant enzyme activity, modulate the endogenous hormone levels, and promote potassium and sodium excretion by the plants. The effect was more significant in salt-sensitive maize cultivars. Bangladesh J. Bot. 52(2): 551-558, 2023 (June) Special

Effects of brassinolide on the physiological characteristics of maize (Zea Mays L.) Cultivars Under salt stress.

Effects of brassinolide on the physiological characteristics of maize under salt stress were investigated. Effect of exogenous application of brassinolide on the antioxidant system, endogenous hormone levels, sodium and potassium ion contents of the plants were measured in a salt-tolerant maize cultivar, Xianyu 335, and a salt-sensitive maize cultivar, Dongnong 253. Brassinolide induced better alleviation of physiological damage in different salt-sensitive maize cultivars under salt stress treatment. Exogenous administration of brassinolide was found to increase the antioxidant enzyme activity, modulate the endogenous hormone levels, and promote potassium and sodium excretion by the plants. The effect was more significant in salt-sensitive maize cultivars. Bangladesh J. Bot. 52(2): 551-558, 2023 (June) Special

Natural variation in ZmNAC087 contributes to total root length regulation in maize seedlings under salt stress

Soil salinity poses a significant challenge to crop growth and productivity, particularly affecting the root system, which is vital for water and nutrient uptake. To identify genetic factors that influence root elongation in stressful environments, we conducted a genome-wide association study (GWAS) to investigate the natural variation associated with total root length (TRL) under salt stress and normal conditions in maize seedlings. Our study identified 69 genetic variants associated with 38 candidate genes, among which a specific single nucleotide polymorphism (SNP) in ZmNAC087 was significantly associated with TRL under salt stress. Transient expression and transactivation assays revealed that ZmNAC087 encodes a nuclear-localized protein with transactivation activity. Further candidate gene association analysis showed that non-coding variations in ZmNAC087 promoter contribute to differential ZmNAC087 expression among maize inbred lines, potentially influencing the variation in salt-regulated TRL. In addition, through nucleotide diversity analysis, neutrality tests, and coalescent simulation, we demonstrated that ZmNAC087 underwent selection during maize domestication and improvement. These findings highlight the significance of natural variation in ZmNAC087, particularly the favorable allele, in maize salt tolerance, providing theoretical basis and valuable genetic resources for the development of salt-tolerant maize germplasm.

ZmmiR169q/ZmNF-YA8 is a module that homeostatically regulates primary root growth and salt tolerance in maize.

In response to salt stress, plants alter the expression of manifold gene networks, enabling them to survive and thrive in the face of adversity. As a result, the growth and development of plant roots could be drastically altered, with significant inhibition of the growth of root meristematic zones. Although it is known that root growth is primarily regulated by auxins and cytokinins, the molecular regulatory mechanism by which salt stress stunts root meristems remains obscure. In this study, we found that the ZmmiR169q/ZmNF-YA8 module regulates the growth of maize taproots in response to salt stress. Salt stress downregulates ZmmiR169q expression, allowing for significant upregulation of ZmNF-YA8, which, in turn, activates ZmERF1B, triggering the upregulation of ASA1 and ASA2, two rate-limiting enzymes in the biosynthesis of tryptophan (Trp), leading to the accumulation of auxin in the root tip, thereby inhibiting root growth. The development of the maize root is stymied as meristem cell division and meristematic zone expansion are both stifled. This study reveals the ZmmiR169q/ZmNF-YA8 module's involvement in maintaining an equilibrium in bestowing plant salt tolerance and root growth and development under salt stress, providing new insights into the molecular mechanism underlying the homeostatic regulation of plant development in response to salt stress.

Research Progress on the Mechanism of Salt Tolerance in Maize: A Classic Field That Needs New Efforts.

Maize is the most important cereal crop globally. However, in recent years, maize production faced numerous challenges from environmental factors due to the changing climate. Salt stress is among the major environmental factors that negatively impact crop productivity worldwide. To cope with salt stress, plants developed various strategies, such as producing osmolytes, increasing antioxidant enzyme activity, maintaining reactive oxygen species homeostasis, and regulating ion transport. This review provides an overview of the intricate relationships between salt stress and several plant defense mechanisms, including osmolytes, antioxidant enzymes, reactive oxygen species, plant hormones, and ions (Na+, K+, Cl-), which are critical for salt tolerance in maize. It addresses the regulatory strategies and key factors involved in salt tolerance, aiming to foster a comprehensive understanding of the salt tolerance regulatory networks in maize. These new insights will also pave the way for further investigations into the significance of these regulations in elucidating how maize coordinates its defense system to resist salt stress.

ZmEREB57 regulates OPDA synthesis and enhances salt stress tolerance through two distinct signalling pathways in Zea mays.

In plant, APETALA2/ethylene-responsive factor (AP2/ERF)-domain transcription factors are important in regulating abiotic stress tolerance. In this study, ZmEREB57 encoding a AP2/ERF transcription factor was identified and its function was investigated in maize. ZmEREB57 is a nuclear protein with transactivation activity induced by several abiotic stress types. Furthermore, two CRISPR/Cas9 knockout lines of ZmEREB57 showed enhanced sensitivity to saline conditions, whereas the overexpression of ZmEREB57 increased salt tolerance in maize and Arabidopsis. DNA affinity purification sequencing (DAP-Seq) analysis revealed that ZmEREB57 notably regulates target genes by binding to promoters containing an O-box-like motif (CCGGCC). ZmEREB57 directly binds to the promoter of ZmAOC2 involved in the synthesis of 12-oxo-phytodienoic acid (OPDA) and jasmonic acid (JA). Transcriptome analysis revealed that several genes involved in regulating stress and redox homeostasis showed differential expression patterns in OPDA- and JA-treated maize seedlings exposed to salt stress compared to those treated with salt stress alone. Analysis of mutants deficient in the biosynthesis of OPDA and JA revealed that OPDA functions as a signalling molecule in the salt response. Our results indicate that ZmEREB57 involves in salt tolerance by regulating OPDA and JA signalling and confirm early observations that OPDA signalling functions independently of JA signalling.

Inhibition of the maize salt overly sensitive pathway by ZmSK3 and ZmSK4

Soil salinity is a worldwide problem that adversely affects plant growth and crop productivity. The salt overly sensitive (SOS) pathway is evolutionarily conserved and essential for plant salt tolerance. In this study, we reveal how the maize shaggy/glycogen synthase kinase 3-like kinases ZmSK3 and ZmSK4, orthologs of brassinosteroid insensitive 2 in Arabidopsis thaliana, regulate the maize SOS pathway. ZmSK3 and ZmSK4 interact with and phosphorylate ZmSOS2, a core member of the maize SOS pathway. The mutants defective in ZmSK3 or ZmSK4 are hyposensitive to salt stress, with higher salt-induced activity of ZmSOS2 than that in the wild type. Furthermore, the Ca2+ sensors ZmSOS3 and ZmSOS3-like calcium binding protein 8 (ZmSCaBP8) activate ZmSOS2 to maintain Na+/K+ homeostasis under salt stress and may participate in the regulation of ZmSOS2 by ZmSK3 and ZmSK4. These findings discover the regulation of the maize SOS pathway and provide important gene targets for breeding salt-tolerant maize.

Cytokinin signaling promotes salt tolerance by modulating shoot chloride exclusion in maize

Excessive accumulation of chloride (Cl−) in the aboveground tissues under saline conditions is harmful to crops. Increasing the exclusion of Cl− from shoots promotes salt tolerance in various crops. However, the underlying molecular mechanisms remain largely unknown. In this study, we demonstrated that a type A response regulator (ZmRR1) modulates Cl− exclusion from shoots and underlies natural variation of salt tolerance in maize. ZmRR1 negatively regulates cytokinin signaling and salt tolerance, likely by interacting with and inhibiting His phosphotransfer (HP) proteins that are key mediators of cytokinin signaling. A naturally occurring non-synonymous SNP variant enhances the interaction between ZmRR1 and ZmHP2, conferring maize plants with a salt-hypersensitive phenotype. We found that ZmRR1 undergoes degradation under saline conditions, leading to the release of ZmHP2 from ZmRR1 inhibition, and subsequently ZmHP2-mediated signaling improves salt tolerance primarily by promoting Cl− exclusion from shoots. Furthermore, we showed that ZmMATE29 is transcriptionally upregulated by ZmHP2-mediated signaling under highly saline conditions and encodes a tonoplast-located Cl− transporter that promotes Cl− exclusion from shoots by compartmentalizing Cl− into the vacuoles of root cortex cells. Collectively, our study provides an important mechanistic understanding of the cytokinin signaling-mediated promotion of Cl− exclusion from shoots and salt tolerance and suggests that genetic modification to promote Cl− exclusion from shoots is a promising route for developing salt-tolerant maize.

New Genes Identified as Modulating Salt Tolerance in Maize Seedlings Using the Combination of Transcriptome Analysis and BSA

(1) Background: Salt stress is an abiotic factor that limits maize yield and quality. A highly salt-tolerance inbred AS5 and a salt-sensitive inbred NX420 collected from Ningxia Province, China, were used to identify new genes for modulating salt resistance in maize. (2) Methods: To understand the different molecular bases of salt tolerance in AS5 and NX420, we performed BSA-seq using an F2 population for two extreme bulks derived from the cross between AS5 and NX420. Transcriptomic analysis was also conducted for AS5 and NX420 at the seedling stage after treatment with 150 mM of NaCl for 14 days. (3) Results: AS5 had a higher biomass and lower Na+ content than NX420 in the seedling stage after treatment with 150 mM NaCl for 14 days. One hundred and six candidate regions for salt tolerance were mapped on all of the chromosomes through BSA-seq using F2 in an extreme population. Based on the polymorphisms identified between both parents, we detected 77 genes. A large number of differentially expressed genes (DEGs) at the seedling stage under salt stress between these two inbred lines were detected using transcriptome sequencing. GO analysis indicated that 925 and 686 genes were significantly enriched in the integral component of the membrane of AS5 and NX420, respectively. Among these results, two and four DEGs were identified as overlapping in these two inbred lines using BSA-seq and transcriptomic analysis, respectively. Two genes (Zm00001d053925 and Zm00001d037181) were detected in both AS5 and NX420; the transcription level of Zm00001d053925 was induced to be significantly higher in AS5 than in NX420 (41.99 times versus 6.06 times after 150 mM of NaCl treatment for 48 h), while the expression of Zm00001d037181 showed no significant difference upon salt treatment in both lines. The functional annotation of the new candidate genes showed that it was an unknown function protein. (4) Conclusions: Zm00001d053925 is a new functional gene responding to salt stress in the seedling stage, which provides an important genetic resource for salt-tolerant maize breeding.

MicroRNA408 negatively regulates salt tolerance by affecting secondary cell wall development in maize.

Although microRNA408 (miR408) is a highly conserved miRNA, the miR408 response to salt stress differs among plant species. Here, we show that miR408 transcripts are strongly repressed by salt stress and methyl viologen treatment in maize (Zea mays). Application of N, N1-dimethylthiourea partly relieved the NaCl-induced down-regulation of miR408. Transgenic maize overexpressing MIR408b is hypersensitive to salt stress. Overexpression of MIR408b enhanced the rate of net Na+ efflux, caused Na+ to locate in the inter-cellular space, reduced lignin accumulation, and reduced the number of cells in vascular bundles under salt stress. We further demonstrated that miR408 targets ZmLACCASE9 (ZmLAC9). Knockout of MIR408a or MIR408b or overexpression of ZmLAC9 increased the accumulation of lignin, thickened the walls of pavement cells, and improved salt tolerance of maize. Transcriptome profiles of the wild-type and MIR408b-overexpressing transgenic maize with or without salt stress indicated that miR408 negatively regulates the expression of cell wall biogenesis genes under salt conditions. These results indicate that miR408 negatively regulates salt tolerance by regulating secondary cell wall development in maize.

Advances in deciphering salt tolerance mechanism in maize

Maize (Zea mays L.) is a global cereal crop whose demand is projected to double by 2050. Along with worsening of farmland salinization, salt stress has become a major environmental threat to the sustainability of maize production worldwide. Accordingly, there is an urgent need to decipher salt-tolerant mechanisms and facilitate the breeding of salt-tolerant maize. As salt tolerance is a complex trait regulated by multiple genes, and maize germplasm varies widely in salt tolerance, efforts have been devoted to the identification and application of quantitative-trait loci (QTL) for salt tolerance. QTL associated with ion regulation, osmotic tolerance, and other aspects of salt tolerance have been discovered using genome-wide association studies (GWAS), linkage mapping, and omics-based approaches. This review highlights recent advances in the molecular-level understanding of salt stress response in maize, in particular in (a) the discovery of salt-tolerance QTL, (b) the mechanisms of salt tolerance, (c) the development of salt-tolerant maize cultivars, and (d) current challenges and future prospects.

ORF355 confers enhanced salinity stress adaptability to S-type cytoplasmic male sterility maize by modulating the mitochondrial metabolic homeostasis.

Moderate stimuli in mitochondria improve wide-ranging stress adaptability in animals, but whether mitochondria play similar roles in plants is largely unknown. Here, we report the enhanced stress adaptability of S-type cytoplasmic male sterility (CMS-S) maize and its association with mild expression of sterilizing gene ORF355. A CMS-S maize line exhibited superior growth potential and higher yield than those of the near-isogenic N-type line in saline fields. Moderate expression of ORF355 induced the accumulation of reactive oxygen species and activated the cellular antioxidative defense system. This adaptive response was mediated by elevation of the nicotinamide adenine dinucleotide concentration and associated metabolic homeostasis. Metabolome analysis revealed broad metabolic changes in CMS-S lines, even in the absence of salinity stress. Metabolic products associated with amino acid metabolism and galactose metabolism were substantially changed, which underpinned the alteration of the antioxidative defense system in CMS-S plants. The results reveal the ORF355-mediated superior stress adaptability in CMS-S maize and might provide an important route to developing salt-tolerant maize varieties.

Maize (Zea mays L.) responses to salt stress in terms of root anatomy, respiration and antioxidative enzyme activity

BackgroundSoil salt stress is a problem in the world, which turns into one of the main limiting factors hindering maize production. Salinity significantly affects root physiological processes in maize plants. There are few studies, however, that analyses the response of maize to salt stress in terms of the development of root anatomy and respiration.ResultsWe found that the leaf relative water content, photosynthetic characteristics, and catalase activity exhibited a significantly decrease of salt stress treatments. However, salt stress treatments caused the superoxide dismutase activity, peroxidase activity, malondialdehyde content, Na+ uptake and translocation rate to be higher than that of control treatments. The detrimental effect of salt stress on YY7 variety was more pronounced than that of JNY658. Under salt stress, the number of root cortical aerenchyma in salt-tolerant JNY658 plants was significantly higher than that of control, as well as a larger cortical cell size and a lower root cortical cell file number, all of which help to maintain higher biomass. The total respiration rate of two varieties exposed to salt stress was lower than that of control treatment, while the alternate oxidative respiration rate was higher, and the root response of JNY658 plants was significant. Under salt stress, the roots net Na+ and K+ efflux rates of two varieties were higher than those of the control treatment, where the strength of net Na+ efflux rate from the roots of JNY658 plants and the net K+ efflux rate from roots of YY7 plants was remarkable. The increase in efflux rates reduced the Na+ toxicity of the root and helped to maintain its ion balance.ConclusionThese results demonstrated that salt-tolerant maize varieties incur a relatively low metabolic cost required to establish a higher root cortical aerenchyma, larger cortical cell size and lower root cortical cell file number, significantly reduced the total respiration rate, and that it also increased the alternate oxidative respiration rate, thereby counteracting the detrimental effect of oxidative damage on root respiration of root growth. In addition, Na+ uptake on the root surface decreased, the translocation of Na+ to the rest of the plant was constrained and the level of Na+ accumulation in leaves significantly reduced under salt stress, thus preempting salt-stress induced impediments to the formation of shoot biomass.

Halotolerant Streptomyces spp. induce salt tolerance in maize through systemic induction of the antioxidant system and accumulation of proline

Plant Growth Promoting Rhizobacteria (PGPR) can mitigate the detrimental effects of salinity in plants. We characterized Streptomyces spp. as halotolerant PGPR and evaluated their influence on salt stress-tolerance mechanisms in maize plants. Bacterial halotolerance was evaluated at concentrations up to 900 mM NaCl, analyzing cell growth, viability, and production of secondary metabolites. The mechanisms of systemic tolerance in plants, such as the enzymatic activity of the antioxidant system and the production of osmolytes, were analyzed in bacterized plants under salt stress (100 and 300 mM NaCl). Isolates proved viable and produced indolic compounds and siderophores under NaCl conditions. Synthesis of indolic compounds and phosphate solubilization were induced in CLV179 by salt stress. The activity of the antioxidant enzymes and the synthesis of proline increased in bacterized plants submitted to salt stress, mainly those treated with isolate CLV97 and CLV179. Response of Streptomyces-treated plant to salinity was observed in roots and leaves, suggesting a mechanism of systemic tolerance. Therefore, bacterization with Streptomyces spp. alleviated the deleterious effects of salinity in maize plants by modulating the enzymatic and non-enzymatic antioxidant mechanisms.

Natural variation and domestication selection of ZmSULTR3;4 is associated with maize lateral root length in response to salt stress.

Soil salinity is a major constraint that restricts crop productivity worldwide. Lateral roots (LRs) are important for water and nutrient acquisition, therefore understanding the genetic basis of natural variation in lateral root length (LRL) is of great agronomic relevance to improve salt tolerance in cultivated germplasms. Here, using a genome-wide association study, we showed that the genetic variation in ZmSULTR3;4, which encodes a plasma membrane-localized sulfate transporter, is associated with natural variation in maize LRL under salt stress. The transcript of ZmSULTR3;4 was found preferentially in the epidermal and vascular tissues of root and increased by salt stress, supporting its essential role in the LR formation under salt stress. Further candidate gene association analysis showed that DNA polymorphisms in the promoter region differentiate the expression of ZmSULTR3;4 among maize inbred lines that may contribute to the natural variation of LRL under salt stress. Nucleotide diversity and neutrality tests revealed that ZmSULTR3;4 has undergone selection during maize domestication and improvement. Overall, our results revealed a regulatory role of ZmSULTR3;4 in salt regulated LR growth and uncovered favorable alleles of ZmSULTR3;4, providing an important selection target for breeding salt-tolerant maize cultivar.

A teosinte-derived allele of an HKT1 family sodium transporter improves salt tolerance in maize.

The sodium cation (Na+ ) is the predominant cation with deleterious effects on crops in salt-affected agricultural areas. Salt tolerance of crop can be improved by increasing shoot Na+ exclusion. Therefore, it is crucial to identify and use genetic variants of various crops that promote shoot Na+ exclusion. Here, we show that a HKT1 family gene ZmNC3 (Zea mays L. Na+ Content 3; designated ZmHKT1;2) confers natural variability in shoot-Na+ accumulation and salt tolerance in maize. ZmHKT1;2 encodes a Na+ -preferential transporter localized in the plasma membrane, which mediates shoot Na+ exclusion, likely by withdrawing Na+ from the root xylem flow. A naturally occurring nonsynonymous SNP (SNP947-G) increases the Na+ transport activity of ZmHKT1;2, promoting shoot Na+ exclusion and salt tolerance in maize. SNP947-G first occurred in the wild grass teosinte (at a allele frequency of 43%) and has become a minor allele in the maize population (allele frequency 6.1%), suggesting that SNP947-G is derived from teosinte and that the genomic region flanking SNP947 likely has undergone selection during domestication or post-domestication dispersal of maize. Moreover, we demonstrate that introgression of the SNP947-G ZmHKT1;2 allele into elite maize germplasms reduces shoot Na+ content by up to 80% and promotes salt tolerance. Taken together, ZmNC3/ZmHKT1;2 was identified as an important QTL promoting shoot Na+ exclusion, and its favourable allele provides an effective tool for developing salt-tolerant maize varieties.

Glycine betaine increases salt tolerance in maize (Zea mays L.) by regulating Na+ homeostasis.

Improving crop salt tolerance is an adaptive measure to climate change for meeting future food demands. Previous studies have reported that glycine betaine (GB) plays critical roles as an osmolyte in enhancing plant salt resistance. However, the mechanism underlying the GB regulating plant Na+ homeostasis during response to salinity is poorly understood. In this study, hydroponically cultured maize with 125 mM NaCl for inducing salinity stress was treated with 100 μM GB. We found that treatment with GB improved the growth of maize plants under non-stressed (NS) and salinity-stressed (SS) conditions. Treatment with GB significantly maintained the properties of chlorophyll fluorescence, including Fv/Fm, ΦPSII, and ΦNPQ, and increased the activity of the antioxidant enzymes for mitigating salt-induced growth inhibition. Moreover, GB decreased the Na+/K+ ratio primarily by reducing the accumulation of Na+ in plants. The results of NMT tests further confirmed that GB increased Na+ efflux from roots under SS condition, and fluorescence imaging of cellular Na+ suggested that GB reduced the cellular allocation of Na+. GB additionally increased Na+ efflux in leaf protoplasts under SS condition, and treatment with sodium orthovanadate, a plasma membrane (PM) H+-ATPase inhibitor, significantly alleviated the positive effects of GB on Na+ efflux under salt stress. GB significantly improved the vacuolar activity of NHX but had no significant effects on the activity of V type H+-ATPases. In addition, GB significantly upregulated the expression of the PM H+-ATPase genes, ZmMHA2 and ZmMHA4, and the Na+/H+ antiporter gene, ZmNHX1. While, the V type H+-ATPases gene, ZmVP1, was not significantly regulated by GB. Altogether these results indicate that GB regulates cellular Na+ homeostasis by enhancing PM H+-ATPases gene transcription and protein activities to improve maize salt tolerance. This study provided an extended understanding of the functions of GB in plant responses to salinity, which can help the development of supportive measures using GB for obtaining high maize yield in saline conditions.

Transcription factor ZmWRKY20 interacts with ZmWRKY115 to repress expression of ZmbZIP111 for salt tolerance in maize.

Maize (Zea mays) is an important cereal crop worldwide. However, its yield and quality are adversely affected by salt stress resulting from soil hypersalinity. Exploring the regulatory mechanisms of stress responses is of vital importance to increase maize seed production. In the present study, we screened ethyl methanesulfonate-induced maize mutants and identified a salt-tolerant mutant. A single base was mutated in ZmWRKY20, leading to the formation of a truncated protein variant. A detailed phenotypic analysis revealed that this mutant had significantly higher resistance to wilting and lower reactive oxygen species levels than the inbred line B73. ZmWRKY20 showed transcriptional activity in yeast and specifically bound W-boxes according to the results of our yeast one-hybrid, electrophoretic mobility shift, and dual-luciferase assays. Overexpression of ZmWRKY20 decreased salt tolerance in maize. Transcriptome profiling revealed that ZmWRKY20 overexpression extensively reprogrammed genes involved in regulating defense and oxidation-reduction responses. The results substantiate that ZmWRKY20 is directly targeted to the basic leucine zipper (bZIP) motif in the transcription factor ZmbZIP111. It was also verified that ZmWRKY20 interacts with ZmWRKY115 and both proteins act jointly to enhance ZmbZIP111 repression. The results indicate that the ZmWRKY20 and ZmWRKY115 transcription factors interact in the nucleus, leading to repression of ZmbZIP111 expression by directly binding its promoter, and increase the sensitivity of maize seedlings to salt stress. The current study improves our understanding of the complicated responses of maize to salt stress.

Effects of seed priming on salt tolerance of maize (Zea mays L.) seedlings by lipo-chitooligosaccharide

Effects of lipo-chitooligosaccharide seed priming on agronomic traits of maize under different salt concentrations (0, 2, 4, 6 and 8 dS/m) were studied. Results showed that the effects of salinity and seed priming on agronomic characteristics were significant at the probability level of 5% (P< 0.05). The increase in salinity up to 10 dS/m negatively influenced all traits. However, seed priming with LCO @ 4ml/kg compensated the adverse effects of salinity on agronomic traits. The regression analysis under salt stress condition showed that aforesaid traits all together contributed 98.4 per cent for salt tolerance. Hence, the novel finding showed that seed priming with LCO signal molecule can enhance the maize tolerance to salinity by improving the physiological changes in seeds which has very high value of implications. Bangladesh J. Bot. 51(2): 381-385, 2022 (June)