Maize Accessions Research Articles

A unified VCF data set from nearly 1,500 diverse maize accessions and resources to explore the genomic landscape of maize.

Efforts to capture and analyze maize nucleotide diversity have ranged widely in scope, but differences in reference genome version and software algorithms used in these efforts inhibit comparison, and these data are generally not available in an easy-to-use visualization platform for quick access and analysis. To address these issues, The Maize Genetics and Genomics Database has collaborated with maize researchers to offer variant data from a diverse set of 1,498 inbred lines, traditional varieties, and teosintes through a standardized variant-calling pipeline against version 5 of the B73 reference genome. The output was filtered for mapping quality, completeness, and linkage disequilibrium, and annotated based on variant effects relative to the B73 RefGen_v5 gene annotations. MaizeGDB has also updated a web tool, SNPversity 2.0, to filter, visualize, and download genotype sets based on genomic locations and accessions of interest, and added external data sets to demonstrate SNPversity 2.0's broad usage. MaizeGDB plans to host annual updates of these resources as additional resequencing data become available, with plans to expand to all publicly available sequence data.

Multi-Omics Analyses Offer Novel Insights into the Selection of Sugar and Lipid Metabolism During Maize Domestication and Improvement.

Over thousands of years of domestication, maize has undergone significant environmental changes. Understanding the genetic and metabolic trace during maize evolution can better contribute to molecular breeding and nutrition quality improvement. This study examines the metabolic profiles and transcriptomes of maize kernels from teosinte, landrace, and maize accessions at 15 days post-pollination. Differentially accumulated metabolites were enriched in sugar and lipid metabolism pathways. The metabolic selection profile exhibited four distinct patterns: continuous increases, constant decrease, initial decline or stability followed by an increase, and initial growth or stability followed by a subsequent decline. Sugars and JA were positive selection while LPCs/LPEs were negative selection during evolution. The expression level of genes related to sugar accumulation was significantly higher in maize, contrasting with enhanced glycolysis and lipid metabolism activity in teosinte. The correlation network highlighted distinct hormonal regulation of sugar and lipid metabolism. We identified 27 candidate genes associated with sugar, lipid, and JA that have undergone strong selection by population genomic regions. The positive selection of the PLD may explain the negative selection of LPCs/LPEs due to substrate competition. These findings enhance our understanding of the evolutionary trajectory of primary metabolism in maize and provide valuable resources for breeding and improvement.

THE PERFORMANCE OF SEVEN ELITE MAIZE ACCESSIONS FROM DIFFERENT AFRICAN ORIGINS UNDER RAIN-FED CONDITIONS IN SOUTH-EASTERN NIGERIA

Maize is an important cereal crop, and millions of Africans rely on it as a major source of carbohydrates in their diet. Grain yield from local maize varieties is generally low. Evaluation of different maize genotypes within a specific region is one way to identify and introduce varieties with high yield potential. This study assessed the yield and agronomic traits of 6 exotic maize accessions and a local variety to compare the performance of the exotic accessions with the local variety. The experiment was laid out as a randomized complete block design with four replications. The treatments included six exotic maize accessions, TZM386, TZM85, TZM16, TZM109, TZM392, and TZM1330, and a local variety ‘Uwep’ the result indicated that there were no significant differences in plant height and plant population at anthesis. Grain yiel among all accessions was not greater than 0.5 t/ha in 2020 but ranged between 1-3 t/ha in 2021. There were no significant differences in grain yield and components between the exotic and local accessions in 2021. In 2020, TZM 386 outperformed the local variety (uwep) in grain yield, ear weight, and number of ears/ha. Multiple linear regression showed a high dependence of grain yield on the growth parameter-plant height and the yield component ear no/ha in 2020 and 2021. This study has revealed differences in yield traits between the local and exotic accessions. The maize accession TZM 386 showed potential for higher grain yield and yield components and appears to be a promising candidate for further research.

Performance evaluation and multivariate analysis of maize accessions against drought stress in Lamjung district, Nepal

The selection of drought-tolerant genotypes from the existing gene pool is a preliminary step for breeding for drought tolerance. Research efforts aimed at exploring the ability of crops to withstand drought stress have not yet touched the realm of reproductive drought performance of local genotypes. To examine how local crop accessions demonstrate varying reproductive performance under drought conditions, twenty accessions of maize (Zea mays L.) were evaluated for six quantitative traits in a two-factor factorial completely randomized design with two replications between February to June of 2023. All the traits under study showed significant differences among the genotypes (p < 0.05). Owing to their grain yield, ear weight, and hundred grain weight, accessions NGRC05592, NGRC05582, NGRC05564, NGRC05565, NGRC05571, and NGRC05569 performed better under drought condition than other tested accessions. Accession NGRC05592 showed the highest yield under drought condition, whereas, NGRC05573 and NGRC05576 showed poor performance. GGE Biplot analysis for grain yield revealed that NGRC05571 and NGRC05592 had the highest mean yield, with the accession NGRC05592 standing out as the stable variety under changing soil moisture levels and performing best among all the tested accessions under drought condition. The possibility of accession NGRC05592 being used as a potential genetic resource for drought breeding programs has been observed, but further studies aiming at its stability under field conditions in diverse agro-climatic regions across different years are encouraged to assure its prospect for developing cultivars suited to drought-affected regions.

Philippine Traditional Maize with Resistance to Asian Corn Borer [Ostrinia furnacalis (Guenée) (Lepidoptera: Crambidae)] Leaf and Stalk Feeding Damage

Maize has been identified as an excellent alternative to rice as a staple food in the Philippines. The Asian corn borer (ACB; Ostrinia furnacalis Guenée), one of the most destructive insect pests of maize, damages plants throughout their vegetative and reproductive stages. Most open-pollinated varieties are threatened by pests and diseases. The CGUARD program investigated the potential of traditional Philippine maize as a source of resistance to major insect pests, including ACB. This paper evaluated the response of the selected 149 Philippine traditional maize accessions to ACB at vegetative and reproductive stages through laboratory bioefficacy procedures for potential resistance without the presence of Bt leaf and stalk-feeding resistance were determined through mean larval survival and mean tunnel length, respectively, after 5 d using laboratory- reared second-instar larvae. Improvements in screening procedures for laboratory assays are detailed in this report. Fourteen (14) accessions were identified to have promising leaf-feeding resistance, whereas 30 accessions were identified for stalk-feeding resistance. The resistance of APN 0088, a white glutinous type of maize from Palawan, to both leaf and stalk feeding of ACB was also validated. The results demonstrate the presence of natural resistance to ACB in traditional maize that has been exposed to the threat of the pest for decades. These promising accessions may be utilized to generate ACB-resistant or-tolerant maize, in addition to other breeding programs. Several pigmented varieties with ACB resistance were also identified, which may be further examined for their nutritional properties and potential as functional foods. By utilizing our traditional varieties, we are boosting local maize production that will benefit small-scale farmers and ultimately providing them with a high-performing variety that is crucial in this time of changing climate.

Seedling root system adaptation to water availability during maize domestication and global expansion.

The maize root system has been reshaped by indirect selection during global adaptation to new agricultural environments. In this study, we characterized the root systems of more than 9,000 global maize accessions and its wild relatives, defining the geographical signature and genomic basis of variation in seminal root number. We demonstrate that seminal root number has increased during maize domestication followed by a decrease in response to limited water availability in locally adapted varieties. By combining environmental and phenotypic association analyses with linkage mapping, we identified genes linking environmental variation and seminal root number. Functional characterization of the transcription factor ZmHb77 and in silico root modeling provides evidence that reshaping root system architecture by reducing the number of seminal roots and promoting lateral root density is beneficial for the resilience of maize seedlings to drought.

Comprehensive Evaluation and Selection of 192 Maize Accessions from Different Sources.

In the period 2022-2023, an analysis of fourteen phenotypic traits was conducted across 192 maize accessions in the Aral region of Xinjiang. The Shannon-Wiener diversity index was employed to quantify the phenotypic diversity among the accessions. Subsequently, a comprehensive evaluation of the index was performed utilizing correlation analysis, principal component analysis (PCA) and cluster analysis. The results highlighted significant findings: (1) A pronounced diversity was evident across the 192 maize accessions, accompanied by complex interrelationships among the traits. (2) The 14 phenotypic traits were transformed into 3 independent indicators through principal component analysis: spike factor, leaf width factor, and number of spikes per plant. (3) The 192 materials were divided into three groups using cluster analysis. The phenotypes in Group III exhibited the best performance, followed by those in Group I, and finally Group II. The selection of the three groups can vary depending on the breeding objectives. This study analysed the diversity of phenotypic traits in maize germplasm resources. Maize germplasm was categorised based on similar phenotypes. These findings provide theoretical insights for the study of maize accessions under analogous climatic conditions in Alar City, which lay the groundwork for the efficient utilization of existing germplasm as well as the development and selection of new varieties.

Physical Traits and Phenolic Compound Diversity in Maize Accessions with Blue-Purple Grain (Zea mays L.) of Mexican Races

Consumer interest in foods enriched with phytochemical compounds for health benefits has prompted plant breeders to focus on developing new cultivars with an enhanced content of specific compounds. Studies regarding the exploration of germplasms of species of great economic importance, such as maize, could be useful in this task. This study aimed to assess the physical grain traits and phenolic compound variations (including anthocyanins, flavonoids, and proanthocyanidins) in blue-purple maize accessions from various Mexican races. We examined 207 accessions from 21 Mexican maize races, evaluating physical grain traits such as weight of one hundred grains (W100G), endosperm type (ET), pigment location, and grain color. Phenolic composition analysis encompassed total soluble phenolics (TSP), total anthocyanin content (TAC), flavonoids (FLAV), and proanthocyanidins (PAs). The predominant endosperm type was floury, with W100G values indicating a large grain size and the pigment primarily located in the aleurone layer. Among phenolic composition variables, only TSP exhibited a normal distribution, while others skewed towards the left side. A hierarchical analysis of phenolic composition data revealed three distinct groups comprising different numbers of Mexican varieties, with TAC proving the most effective for grouping. Our comprehensive exploration of maize diversity featuring blue-purple grain coloration has led to the identification of novel maize varieties with outstanding phenolic contents.

Cytoplasmic genome contributions to domestication and improvement of modern maize

BackgroundStudies on maize evolution and domestication are largely limited to the nuclear genomes, and the contribution of cytoplasmic genomes to selection and domestication of modern maize remains elusive. Maize cytoplasmic genomes have been classified into fertile (NA and NB) and cytoplasmic-nuclear male-sterility (CMS-S, CMS-C, and CMS-T) groups, but their contributions to modern maize breeding have not been systematically investigated.ResultsHere we report co-selection and convergent evolution between nuclear and cytoplasmic genomes by analyzing whole genome sequencing data of 630 maize accessions modern maize and its relatives, including 24 fully assembled mitochondrial and chloroplast genomes. We show that the NB cytotype is associated with the expansion of modern maize to North America, gradually replaces the fertile NA cytotype probably through unequal division, and predominates in over 90% of modern elite inbred lines. The mode of cytoplasmic evolution is increased nucleotypic diversity among the genes involved in photosynthesis and energy metabolism, which are driven by selection and domestication. Furthermore, genome-wide association study reveals correlation of cytoplasmic nucleotypic variation with key agronomic and reproductive traits accompanied with the diversification of the nuclear genomes.ConclusionsOur results indicate convergent evolution between cytoplasmic and nuclear genomes during maize domestication and breeding. These new insights into the important roles of mitochondrial and chloroplast genomes in maize domestication and improvement should help select elite inbred lines to improve yield stability and crop resilience of maize hybrids.

Evidence that variation in root anatomy contributes to local adaptation in Mexican native maize.

Mexican native maize (Zea mays ssp. mays) is adapted to a wide range of climatic and edaphic conditions. Here, we focus specifically on the potential role of root anatomical variation in this adaptation. Given the investment required to characterize root anatomy, we present a machine-learning approach using environmental descriptors to project trait variation from a relatively small training panel onto a larger panel of genotyped and georeferenced Mexican maize accessions. The resulting models defined potential biologically relevant clines across a complex environment that we used subsequently for genotype-environment association. We found evidence of systematic variation in maize root anatomy across Mexico, notably a prevalence of trait combinations favoring a reduction in axial hydraulic conductance in varieties sourced from cooler, drier highland areas. We discuss our results in the context of previously described water-banking strategies and present candidate genes that are associated with both root anatomical and environmental variation. Our strategy is a refinement of standard environmental genome-wide association analysis that is applicable whenever a training set of georeferenced phenotypic data is available.

Drought tolerance screening of maize accessions at early growth stage in the mid-hills of Nepal

Drought tolerance screening of maize accessions at early growth stage in the mid-hills of Nepal

Exploring Genetic Diversity of Maize (&lt;em&gt;Zea mays&lt;/em&gt; L.) Accessions in Sri Lanka by Employing SSR Markers on Photosynthetic, Canopy Architectural and Grain Yield Traits

Purpose: The favorable alleles identified in maize landraces are treasurable resources to enhance the genetic base of crop breeding efforts. Therefore, our pioneering research aimed to explore SSR markers related to maize canopy architectural, photosynthetic and yield traits and hence to study the genetic diversity of 19 local maize accessions compared with high-performing maize cultivar Bhadra, as standard variety. Research Method: Genomic DNA extraction was done from young leaves of maize seedlings using standard protocols. The SSR markers employed were phi065, phi116, umc1065, umc1066, umc1222, umc1231, umc1545, bnlg155, bnlg249 and bnlg1805. Data analysis was performed using GenAlex and DARwin software. Findings: Four of the used markers (umc1066, bnlg1805, phi116, and phi065) had PIC values higher than that of the overall mean (0.692), showing their potential in this genetic diversity study. These markers are mainly associated with leaf area index, plant height, leaf chlorophyll content and quantum efficiency of photosystem II. The highest genetic diversity measures were observed in SEU2, SEU17, SEU18 and SEU23, compared to Bhadra while the lowest were in SEU3. The level of inbreeding was higher in SEU8. Cluster analysis identified three major genetic groups and the landraces collected from various areas did not exhibit any geographical association. Research Limitations: Large number of SSR markers are need to explore biomass and grain yield traits. Original/Value: These results will explore the potential uses of Sri Lankan maize accessions to identify best genetic clusters of germplasm with enhanced plant canopy architectural, photosynthesis and grain yield to be utilized in maize breeding programs.

Agro-morphological characterization of Pakistani maize accessions using qualitative and quantitative traits.

Agro-morphological characterizations offer robust and vigorous means for the precise characterization of germplasm to be used in breeding programs. Here, agro-morphological features-based analyses were considered to figure out the genetic variability within 99 maize accessions and five (5) check varieties including Azam, W. Islamabad, Haq Nawaz, Ev-5 and Evr197. A total of 28 important agro-morphological traits were accounted in the field trails at Hazara University Mansehra Pakistan, during spring 2015. The maximum variation was detected in grain weight per cob (53.43), followed by number of kernels per row (38.64) and flag leaf area (cm2), (38.09%). Cluster analysis divided the 99 maize accession with five check varieties of maize accessions into 7 clusters following the hierarchical clustering. Cluster II recorded 29 genotypes with maximum grain yield per cob, and highest flag leaf length, followed by cluster IV. Lowest grain yield per cob was noted for accessions of cluster I. Similarly, cluster VII consisted of accession with the longest cob length. Moreover, the investigations also revealed that the primary constituent among first five principal components with an eigen value about more than 0.98 in relation to 68.75% of the total variants. PCI accounted for 25.53%, PCII contributed 18.31%, and PCIII is 9.88% of the overall morphological variability were significant contributors were grain weight per cob, number of kernel per row, 1000 grain weight. The identification of a significant level of genetic diversity during the present investigation having implications for maize germplasm characterisation, conservation, and breeding programs aiming at developing improvement maize cultivars.

Conservation and diversity of the pollen microbiome of Pan-American maize using PacBio and MiSeq.

Pollen is a vector for diversification, fitness-selection, and transmission of plant genetic material. The extent to which the pollen microbiome may contribute to host diversification is largely unknown, because pollen microbiome diversity within a plant species has not been reported, and studies have been limited to conventional short-read 16S rRNA gene sequencing (e.g., V4-MiSeq) which suffers from poor taxonomic resolution. Here we report the pollen microbiomes of 16 primitive and traditional accessions of maize (corn) selected by indigenous peoples across the Americas, along with the modern U.S. inbred B73. The maize pollen microbiome has not previously been reported. The pollen microbiomes were identified using full-length (FL) 16S rRNA gene PacBio SMRT sequencing compared to V4-MiSeq. The Pan-American maize pollen microbiome encompasses 765 taxa spanning 39 genera and 46 species, including known plant growth promoters, insect-obligates, plant pathogens, nitrogen-fixers and biocontrol agents. Eleven genera and 13 species composed the core microbiome. Of 765 taxa, 63% belonged to only four genera: 28% were Pantoea, 15% were Lactococcus, 11% were Pseudomonas, and 10% were Erwinia. Interestingly, of the 215 Pantoea taxa, 180 belonged to a single species, P. ananatis. Surprisingly, the diversity within P. ananatis ranged nearly 10-fold amongst the maize accessions analyzed (those with ≥3 replicates), despite being grown in a common field. The highest diversity within P. ananatis occurred in accessions that originated near the center of diversity of domesticated maize, with reduced diversity associated with the north-south migration of maize. This sub-species diversity was revealed by FL-PacBio but missed by V4-MiSeq. V4-MiSeq also mis-identified some dominant genera captured by FL-PacBio. The study, though limited to a single season and common field, provides initial evidence that pollen microbiomes reflect evolutionary and migratory relationships of their host plants.

Uncovering microsatellite markers associated with agronomic traits of South Sudan landrace maize.

Maize has great importance in South Sudan as the most cultivated cereal after sorghum; however, numerous challenges are encountered in its production. To raise maize production, it is critical to exploit the wealth of its genetic variation for grain yield enhancement. This study aimed to conduct association analysis to identify specific simple sequence repeat (SSR) markers associated with quantitative agronomic traits. Genetic variation and population structure were investigated among 31 maize accessions by association analysis using 50 SSR markers and seven quantitative agronomic traits. The genotypes exhibited abundant genetic variation, and 418 alleles were detected with an average of 8.4 alleles per locus. The average genetic diversity, major allele frequency, and polymorphic information content were 0.754, 0.373, and 0.725, respectively. The population structure based on 50 SSR markers divided the maize accessions into two main groups and an admixed group without considering their descent. Association analysis was performed using a general linear model (Q GLM) and a mixed linear model (Q + K MLM). Q GLM detected 44 trait-marker associations involving 23 SSR markers. Q + K MLM detected four marker-trait associations involving three SSR markers (umc2286, umc1303, umc1429) associated with days to tasseling, days to silking, leaf length, and leaf width. The detected significant SSR markers related to agronomic traits could be useful for future genetic studies. Additionally, markers affecting several agronomic traits and overlapped SSR markers require further testing on a wide range of genotypes prior to their consideration as candidate markers for marker assisted selection for South Sudan maize improvement.

Genetic Variability in Carotenoid Contents in a Panel of Genebank Accessions of Temperate Maize from Southeast Europe.

Carotenoids are an abundant group of lipid-soluble antioxidants in maize kernels. Maize is a key target crop for carotenoid biofortification focused on using conventional plant breeding in native germplasm of temperate areas traced back partially to traditional cultivars (landraces). In this study, the objectives were to determine the variability of lutein (LUT), zeaxanthin (ZEA), α-cryptoxanthin (αCX), β-cryptoxanthin (βCX), α-carotene (αC), and β-carotene (βC) contents in the grain of 88 accessions of temperate maize from the Croatian genebank, and to evaluate the relationships among the contents of different carotenoids as well as the relationships between kernel color and hardness and carotenoid content. Highly significant variability among the 88 accessions was detected for all carotenoids. On average, the most abundant carotenoid was LUT with 13.2 μg g-1 followed by ZEA with 6.8 μg g-1 dry matter. A Principal Component Analysis revealed a clear distinction between α- (LUT, αCX, and αC) and β-branch (ZEA; βCX, and βC) carotenoids. β-branch carotenoids were positively correlated with kernel color, and weakly positively associated with kernel hardness. Our results suggest that some genebank accessions with a certain percentage of native germplasm may be a good source of carotenoid biofortification in Southeast Europe. However, due to the lack of association between LUT and ZEA, the breeding process could be cumbersome.

The Influence of the Genotype and Planting Density on the Structure and Composition of Root and Rhizosphere Microbial Communities in Maize.

Maize has the largest cultivation area of any crop in the world and plays an important role in ensuring food security. High-density planting is essential for maintaining high maize yields in modern intensive agriculture. Nonetheless, how high-density planting and the tolerance of individual genotypes to such planting shape the root-associated microbiome of maize is still unknown. In this study, we analyzed the root and rhizosphere bacterial communities of two maize accessions with contrasting shoot architectures grown under high- and low-density planting conditions. Our results suggested that maize hosted specific, distinct bacterial communities in the root endocompartment and that the maize genotype had a significant effect on the selection of specific microbes from the rhizosphere. High-density planting also had significant effects on root-associated bacterial communities. Specifically, genotype and high-density planting coordinated to shape the structure, composition, and function of root and rhizosphere bacterial communities. Taken together, our results provide insights into how aboveground plant architecture and density may alter the belowground bacterial community in root-associated compartments of maize.

Drought stress induced by polyethylene glycol (PEG) in local maize at the early seedling stage

Drought stress adversely impacts growth, crop production, reproductive organ development, and yield characteristics in maize. As a drought-sensitive crop, maize (Zea mays L.) shows considerable varietal differences. A study was conducted at the Tissue Culture Laboratory, Department of Biology, Faculty of Mathematics and Natural Sciences, University of North Sumatra, Medan, Indonesia in order to identify drought-tolerant maize varieties. During germination and early seedling growth, 16 local accessions were evaluated for drought tolerance. Based on local climate and soil conditions, these specific accessions were chosen. The varieties were tested against five levels of drought stress imposed by Polyethylene glycol 6000 (PEG-6000) at 10, 20, 30, 40, and 50%. An experiment with three replications was conducted using a completely randomized design. In the study, local maize accessions (BI3, SB5, DS2, and MN3) and the hybrid variety (H) showed the capability of tolerating drought stress. Generally, germination time, germination percent and vigor index, root and shoot length, shoot ratio, and fresh and dry weight were decreased by increasing PEG concentrations (up to 50%). According to ANOVA results, shoot water content was not significantly affected by the PEG, nor was the interaction between the PEG and the accessions. The root water content, however, was significantly affected by PEG, and the interaction between PEG and accessions. Although interactions between accessions with low PEG concentrations improved germination characteristics, the root histology of the accessions varied. According to drought tolerance indexes, five maize accessions are drought-tolerant, including H (0.683), SB5 (0.617), DS2 (0.565), MN3 (0.512), and BI3 (0.504). The drought-tolerant varieties are recommended in regions with low rainfall or low water sources since they are less water-intensive and produce higher yields.

Water absorption kinetics of blue maize (Zea mays L.) and influence on wet-milling properties

The hydration behaviours of 15 blue maize accessions (Elotero de Sinaloa) were investigated, revealing the typical Downward Concave Shape. The Peleg model, a noted water absorption equation, suitably (r > 0.99, MRDM <4, SUMSQ <13) described the hydration kinetics. The Peleg constants K1 [(0.034–0.286 h (g/100 g solids)−1], a measure of the hydration rate, and K2 [(0.026–0.041 g/100 g solids)−1] that measures maximum absorbability, as well as predicted equilibrium moisture content, ME (39.55–50.13 g/100 g solids) were sample dependent. Multivariate analyses, Principal Component Analysis (PCA) and Agglomerative Hierarchical Clustering (AHC), that associated the water absorption kinetic parameters, physicochemical, and wet-milling characteristics of the kernels revealed significant (P ≤ 0.05) differences. Five PCs covered 90% of the variations, and AHC grouped the accessions into 3 clusters according to their dissimilarities. A further AHC analysis that included published data from 42 Mexican commercial white and yellow maize samples to solidly understand water absorption kinetics of maize generally, grouped the 57 samples into clusters that revealed important color-dependent and color-independent differences. The blue maize accessions presented particularities in their kernels, suggesting the prevalence of a soft or floury endosperm that enhanced water absorption, thereby favoring their processing (e.g., wet-milling) properties.

Maize and heat stress: Physiological, genetic, and molecular insights.

Global mean temperature is increasing at a rapid pace due to the rapid emission of greenhouse gases majorly from anthropogenic practices and predicted to rise up to 1.5°C above the pre-industrial level by the year 2050. The warming climate is affecting global crop production by altering biochemical, physiological, and metabolic processes resulting in poor growth, development, and reduced yield. Maize is susceptible to heat stress, particularly at the reproductive and early grain filling stages. Interestingly, heat stress impact on crops is closely regulated by associated environmental covariables such as humidity, vapor pressure deficit, soil moisture content, and solar radiation. Therefore, heat stress tolerance is considered as a complex trait, which requires multiple levels of regulations in plants. Exploring genetic diversity from landraces and wild accessions of maize is a promising approach to identify novel donors, traits, quantitative trait loci (QTLs), and genes, which can be introgressed into the elite cultivars. Indeed, genome wide association studies (GWAS) for mining of potential QTL(s) and dominant gene(s) is a major route of crop improvement. Conversely, mutation breeding is being utilized for generating variation in existing populations with narrow genetic background. Besides breeding approaches, augmented production of heat shock factors (HSFs) and heat shock proteins (HSPs) have been reported in transgenic maize to provide heat stress tolerance. Recent advancements in molecular techniques including clustered regularly interspaced short palindromic repeats (CRISPR) would expedite the process for developing thermotolerant maize genotypes.