Search Results (62)

Meeting the rising demand for staple grains now requires cultivars that combine high yield, enhanced nutritional value, and strong chemical resilience. Blue-kernel landraces from central Mexico are rich in anthocyanins yet remain highly susceptible to post-emergence herbicides, whereas modern hybrids detoxify these compounds through cytochrome P450 (CYP450) enzymes. We crossed the anthocyanin-rich variety Polimaize with a CYP450-tolerant hybrid and evaluated the two parents and their F₁ segregants (designated “White” and “Yellow”) under greenhouse applications of mesotrione (75 g a.i. ha⁻¹), nicosulfuron (30 g a.i. ha⁻¹), and their mixture. Across 160 plants, the hybrid retained 95% of control dry matter and showed ≤7% foliar injury under all treatments, whereas Polimaize lost 28% biomass and exhibited 36% injury after nicosulfuron. The Yellow class matched hybrid performance while maintaining a blue pericarp and a β-carotene-rich endosperm, demonstrating that nutritional and agronomic traits can be stacked. The White class displayed heterosis-driven compensatory growth, exceeding its untreated biomass by 60% with nicosulfuron and by 82% with the mixture despite transient bleaching. Chlorophyll and carotenoid fluorescence revealed rapid, zeaxanthin-linked photoprotection in all tolerant genotypes, consistent with accelerated CYP450-mediated detoxification. These findings show that broad-spectrum herbicide tolerance can be introgressed into pigment-rich germplasm through conventional breeding, providing a non-transgenic path to herbicide-ready, anthocyanin-rich maize. The strategy preserves local biodiversity while delivering cultivars suited to intensive, weed-competitive agriculture and offers a template for integrating metabolic resilience into other native crops. Full article

The launch of a successful quality-oriented breeding program requires both mining the residual diversity in grain quality parameters contained in the elite, high-yielding breeding material with good agronomic performance and introgression of new germplasm, such as local landraces, with a high level of targeted quality parameters per se. This study analyzed the combining abilities of 31 maize landraces and two divergent inbred lines–testers (ZPL217 and ZPL-255/75-5) regarding the yield and protein, starch, and lipid content, assessed by Near Infrared Reflectance (NIR) spectroscopy as a fast, non-destructive, and cost-effective method. The general combining ability (GCA) defines the average behavior of genotype in hybrid combination, resulting from additive gene action, so positive GCA values of landraces AN13 and AN197 for protein, AN632 for lipids, and AN594 for starch content indicate that they can be valuable sources of the mentioned properties in quality-oriented maize breeding programs. The obtained correlation between starch content and protein and yield (−0.948 **; 0.587 **) pointed out that an increase in the protein content during breeding will be accompanied by a decrease in the starch content and yield. The specific combining ability (SCA) of the testers used, suggests their possible application in establishing and improving quality breeding programs’ initial material. Full article

In Mesoamerica, maize is one of the most important food crops, with México being the center of its origin, domestication, and diversity. The state of Chiapas in southern Mexico is one of the areas with the highest maize landrace diversity. However, information on its genetic diversity, conservation status, and the potential use of maize landraces throughout the entire Chiapas region is lacking. One region where local farmers use and preserve a wide diversity of maize landraces is the Zoque region. Until now, however, the genetic diversity of these maize landraces has not been studied. The aim of this study was to analyze the diversity and genetic structure of maize cultivated in the Zoque region, from Chiapas, Mexico, by using 17 landraces and 48 ISSR loci. The analysis revealed two genetic groups based on geographical origin. The genetic diversity level was moderate (Hbay = 0.29 and I = 0.36) and distributed mainly within landraces (70%). The maize landrace blanco belongs to the Tuxpeño race and Bacalito blanco belongs to the Olotillo race from the Miguel Hidalgo municipality have greater diversity values (Hbay = 0.36, I = 0.45 and Hbay = 0.35, I = 0.45, respectively). The results indicated that the maize landraces cultivated in the Zoque region, Chiapas, Mexico, constitute a valuable genetic resource that can be used for genetic improvement and in conservation programs. Full article

The root system plays an important role in the efficient absorption of nitrogen (N), but there is limited understanding of the growth characteristics of maize roots of different genotypes and their dynamic response to N supply. In this study, landraces in the 1950s and modern hybrids, modern hybrids and their parents, inbred lines with different N efficiency and standard inbred line B73 were used, combined with the dynamic culture method, to observe the dynamic changes in root growth under long-term N stress conditions. The results showed that there were genotypic differences in the response of maize roots to low N. Low N enhances root growth earlier than the increases in shoot-to-root dry matter allocation. With the extension of low N stress, the root biomass of each genotype basically increased significantly from 3 to 6 days and then was gradually reversed by high N on the 12th day. As for shoot biomass, 11 genotypes began to decrease significantly from 6 to 9 days after low-N stress. The total axial root length, primary root length, seminal root length, and the first and second whorl crown root length of seven genotypes were increased more or less under low N. With the extension of N stress, the number of third and fourth whorl crown roots decreased significantly, which indicated that regulation of root elongation is earlier than that of crown root initiation. As the degree of low-N stress increased, the trend of total lateral root length changes in different genotypes could be divided into three categories, indicating that the response of lateral root growth to low-N stress is genotype-dependent. With the advancement of the breeding process, the roots of modern hybrids become smaller but more responsive to low-N stress. The root phenotypes of Zhengdan958 and Xianyu335 come from different genetic models. Compared with embryonic roots, the crown roots of B73 have a more active role in adapting to low-N stress. Shoot N concentration may reflect plant internal N status, which plays a regulatory role in root morphogenesis. Full article

Maize production is deficient in arid countries such as Tunisia. To assess maize yield and estimate productivity gaps among Tunisian farmers in consideration of climate change challenges, a survey was conducted that included 50 farms in 10 governorates, focusing on agronomic practices, seed type adoptions, and socioeconomic parameters. The yield gaps related to water resources and farmers’ technical efficiency represented 26.8% and 32.9%, respectively, while for water productivity, the gaps related to water resources and technical efficiency were 32.2% and 31.3%, respectively. Hybrid varieties were among the 25% yield increase compared to local landraces. Farmers retain local landraces mainly for their food quality. Favorable climatic conditions in the northern regions of Tunisia are among the reasons for higher yield compared to the central and southern areas, which registered a yield reduction of 9.2% and 17%, respectively. The Tobit analyses showed that sowing rate, geographic location, type of variety, and fertilization are the most significant factors contributing to technical inefficiencies. For further increases in maize yield in Tunisia, improving agricultural practices, water management, and using high-yielding varieties are essential. Full article

In the framework of a Collaboration Agreement between CREA and ARSIAL, a morpho-phenological, chemical, and genetic characterization of maize populations native to the Lazio region was carried out. During 2022 and 2023, a set of 50 accessions, belonging both to ARSIAL and CREA maize collections, were multiplied in Bergamo. Morpho-phenological descriptors were recorded in the field: plant height, ear height, and male and female flowering time. The grain chemical composition in terms of protein, lipid, starch, ash and fiber was evaluated by near-infrared spectroscopy (NIRS). A double-digest restriction-site-associated DNA sequencing (ddRADseq) strategy was used to genotype the landraces. The two collections were not significantly different in terms of grain chemical composition. On the other hand, the ARSIAL and CREA germplasm showed a different distribution in the three cluster-based population structure obtained by ddRADseq, which largely corresponded to the distribution map of their collection sites. The materials from the Lazio region maintained by ARSIAL and CREA were revealed to be different. The comparison between the two groups of landraces showed the importance of characterizing germplasm collections to promote the recovery and valorization of local biodiversity. Full article

Southern corn rust (SCR) is one of the most destructive foliar diseases in maize (Zea mays L.), resulting in significant yield losses. Therefore, the continuous identification of disease-resistant germplasm and the deployment of resistant hybrids is essential for durably controlling SCR. The objective of this research was to identify and characterize resistance loci against SCR in maize to expand disease management strategies. Here, we identified a maize landrace with high resistance to SCR ‘Silunuo’ (SLN) approaching complete immunity. We backcrossed it with a susceptible inbred line, N531, to generate a stable SCR-resistant introgression line N531_R. By crossing it with F35 (a susceptible inbred line), we created a large F₂ segregating population and mapped a major SCR-resistant locus on chromosome 10, known as RppSLN. Based on the genome assembly and annotation, we found that RppSLN harbors two NBS-LRR (nucleotide binding site–leucine-rich repeat) genes, namely Zmays10G000430 and Zmays10G000440. These NBS-LRR genes were significantly induced during artificial inoculation with Puccinia polysora, suggesting that they might be candidate genes collectively contributing to the resistance level at this locus. In conclusion, this study identified a major SCR resistance locus directly isolated from a landrace, providing valuable support and information for expanding new disease-resistant germplasms and promoting the utilization of landraces. Full article

The plant seed-borne microbiome comprises microorganisms vertically inherited from the mother plant. This microbiome is often linked to early-life protection and seedling growth promotion. Herein, we compare the seed-borne bacteriomes of a commercial hybrid (Santa Helena) and a landrace maize variety (Sol da Manhã). The landrace variety displays a more diverse seed-borne microbiome, featuring a variety of taxa across samples with an average Shannon’s diversity index of 1.12 compared to 0.45 in the hybrid variety. The landrace variety also showed a greater alpha diversity of 165.8, in contrast to 144.1 in the hybrid. Although both microbiomes lack a functional nitrogen fixation apparatus, we found a remarkably distinct presence of genes associated with phytohormone production and phosphate solubilization, particularly in the landrace variety. In addition, we recovered 18 metagenome-assembled genomes (MAGs), including four from potentially novel species. Collectively, our results allow for a better understanding of the contrasting diversity between maize varieties. The higher potential for phytohormone production in landraces, the absence of nif genes in both varieties, and the identification of core microbiome taxa offer valuable insights into how microbial communities impact plant health and development. This knowledge could pave the way for more sustainable and innovative agricultural practices in crop management. Full article

Root system architecture is pivotal for the acquisition of water and nutrients in maize, serving as an essential foundation for achieving high and stable yields. Identification of the genetic components and natural variations determining root traits may facilitate molecular breeding of maize varieties with better root traits. Melatonin plays an important role in plant physiology and development. In this study, nine melatonin biosynthesis genes were re-sequenced in 348 inbred lines, 68 landraces, and 32 teosintes to investigate variations related to maize root traits. The analysis of nucleotide diversity suggested that these genes may have undergone selection, particularly within their promoter regions. Marker–trait association analysis identified 26 variants significantly associated with six root traits. Five variations within the ZmTDC4 promoter were significantly correlated with both total root length (TRL) and lateral root length (LRL). Among these, SNP-1784 explained the most phenotypic variation of root traits, including TRL and LRL, that has undergone selection throughout maize domestication and improvement. Furthermore, knockout of ZmTDC4 in maize resulted in a pronounced reduction in root length, underscoring its critical role in root development. Collectively, these findings elucidate the role of melatonin synthesis genes in root development and identified favorable alleles, thus providing key loci for breeding maize varieties with superior root systems. Full article

The relationships between plants and bacteria are essential in agroecosystems and bioinoculant development. The leaf endophytic Pseudomonas protegens E1BL2 was previously isolated from giant Jala maize, which is a native Zea mays landrace of Nayarit, Mexico. Using different Mexican maize landraces, this work evaluated the strain’s plant growth promotion and biocontrol against eight phytopathogenic fungi in vitro and greenhouse conditions. Also, a plant field trial was conducted on irrigated fields using the hybrid maize Supremo. The grain productivity in this assay increased compared with the control treatment. The genome analysis of P. protegens E1BL2 showed putative genes involved in metabolite synthesis that facilitated its beneficial roles in plant health and environmental adaptation (bdhA, acoR, trpE, speE, potA); siderophores (ptaA, pchC); and extracellular enzymes relevant for PGPB mechanisms (cel3, chi14), protection against oxidative stress (hscA, htpG), nitrogen metabolism (nirD, nit1, hmpA), inductors of plant-induced systemic resistance (ISR) (flaA, flaG, rffA, rfaP), fungal biocontrol (phlD, prtD, prnD, hcnA-1), pest control (vgrG-1, higB-2, aprE, pslA, ppkA), and the establishment of plant-bacteria symbiosis (pgaA, pgaB, pgaC, exbD). Our findings suggest that P. protegens E1BL2 significantly promotes maize growth and offers biocontrol benefits, which highlights its potential as a bioinoculant. Full article

The ECPGR European Evaluation Network (EVA) for Maize involves genebanks, research institutions, and private breeding companies from nine countries focusing on the valorization of maize genetic resources across Europe. This study describes a diverse collection of 626 local landraces and traditional varieties of maize (Zea mays L.) from nine European genebanks, including criteria for selection of the collection and its genetic and phenotypic diversity. High-throughput pool genotyping grouped the landraces into nine genetic groups with a threshold of 0.6 admixture, while 277 accessions were designated admixed and likely to have resulted from previous breeding activities. The grouping correlated well with the geographic origins of the collection, also reflecting the various pathways of introduction of maize to Europe. Phenotypic evaluations of 588 accessions for flowering time and plant architecture in multilocation trials over three years confirmed the great diversity within the collection, although phenotypic clusters only partially correlated with the genetic grouping. The EVA approach promotes conservation of genetic resources and opens an opportunity to increase genetic variability for developing improved varieties and populations for farmers, with better adaptation to specific environments and greater tolerance to various stresses. As such, the EVA maize collection provides valuable sources of diversity for facing climate change due to the varieties’ local adaptation. Full article

Maize productivity in the central belt plays a significant role in the food security of China. With good adaptability and disease resistance, landrace germplasm is important for maize improvement. A total of 246 landrace accessions were collected from the maize belts in central China and genotyped with the SLAF-seq (Specific-Locus Amplified Fragment Sequencing) method, and 144,650 SNPs were obtained for each accession. The results showed that the landrace accessions could be divided into three major groups. In the cluster results, Group I included 64 accessions, which mainly belonged to the landrace of White horse teeth; Group II had 71 accessions, which mainly belonged to the lantern red landraces; the rest of the 116 accessions were clustered as Group III, including a variety of types landraces and seven indicator inbred lines. In the results of structure and multidimensional scaling, the accessions’ attribution differed with the clusters, the main reason for which is the attribution change in intermediate germplasms. Linkage disequilibrium decay distance was 0.98 kb, which was much lower than that of temperate and tropical maize inbred lines, indicated the much higher genetic diversity of landrace germplasms. The results can help us select suitable landrace germplasms and speed up the process of inbred line development and maize improvement. Full article

The growing interest in maize landraces over the past two decades has led to the need to characterize the Italian maize germplasm. In Italy, hundreds of maize landraces have been developed, but only a few of them have been genetically characterized, and even fewer are currently employed in agriculture or for breeding purposes. In the present study, 13 maize landraces of the west Emilia-Romagna region were morphologically and genetically characterized. These accessions were sampled in 1954 from three provinces, Modena, Parma, and Piacenza, during the characterization project of Italian maize landraces. The morphological characterization of these 13 accessions was performed according to the UPOV protocol CPVO/TP2/3, examining 34 phenotypic traits. A total of 820 individuals were genotyped with 10 SSR markers. The genetic characterization revealed 74 different alleles, a F_ST mean value of 0.13, and a Nm mean of 1.73 over all loci. Moreover, AMOVA analysis disclosed a low degree of differentiation among accessions, with only 13% of genetic variability found between populations, supporting PCoA analysis results, where the first two coordinates explained only 16% of variability. Structure analysis, supported by PCoA, showed that only four accessions were clearly distinguished for both K = 4 and 6. Italian landraces can be useful resources to be employed in maize breeding programs for the development of new varieties, adapted to different environmental conditions, in order to increase crop resilience and expand the maize cultivation area. Full article

Suboptimal temperatures at sowing and emergence affect the early development of maize, with potentially irreversible effects later in the growing season. We studied recovery from cold stress of an inbred line (B73) and 13 Doubled Haploid lines derived from a European flint maize landrace. After a cold treatment (20–12 °C, day–night) from sowing to seedling establishment, seedlings were transplanted and grown in the greenhouse until the V8 stage (eight leaves fully developed), when we measured agronomically relevant plant traits and spectral indices of mature leaves. Survival rates of transplanted seedlings after cold treatment ranged from 10% to 100%. After a strong delay in early development due to cold, the surviving plants were able to compensate for this delay at later stages of recovery. They reached the V8 stage after only five more growing degree days than plants grown under the control treatment (25–18 °C, day–night). Plants from the most cold-tolerant genotypes (PE0401 and PE0100) accumulated more root and shoot biomass at the end of the recovery phase compared with the same genotypes exposed to the control treatment. The genotypes with the most plastic leaf morphological traits (PE0161 and PE0072) had little reduction in leaf biomass at the end of the recovery phase in comparison with less responsive genotypes such as PE0171. We conclude that genotypes that survived cold treatment with minimal cold damage of seedling leaves can be candidates for further cold recovery studies and breeding. Nevertheless, such studies must take trait acclimation for other suboptimal conditions into consideration. Full article

Maize is part of the traditional diet of Mexico and other Latin American countries. The diverse varieties of maize produced by adaptation to different regions and climates are known as creole or native maize. The characteristics and nutritional contributions of each of these native maize are relatively diverse areas of study. This work specifically analyzes the nutritional aspects of creole maize grown in the Sierra Gorda in Querétaro. For this, a proximal chemical analysis was carried out, with a quantification of polyphenolic compounds and antioxidant capacities using the ABTS (2,20-azinobis (3-ethyl-benzothiazolin,6-sulfonic acid) and DPPH (2,2-difenil-1-picrilhidrazilo) methods to examine four landraces and one commercial hybrid control. The results indicate that, in general, the landraces present similar—and, in some cases, higher—nutritional indices than the commercial hybrid. With regard to polyphenolic compounds, the Elotes Occidentales and Tuxpeño varieties present greater amounts of total phenols and antiradical activity (ARA), as well as a higher concentration of flavonoids and percentage inhibition, respectively. Condensed tannins are identified both in the creole varieties and in the commercial hybrid. Creole maize presents important nutritional characteristics and can be a good source of antioxidant compounds, which can help the population as a source of food and in the prevention of chronic diseases. Full article