Maize Landraces Research Articles

Characterization of Mimban maize landrace from North-Eastern Himalayan region using microsatellite markers

The North-Eastern Himalayan (NEH) region of India is endowed with rich maize genetic resources which is important from both genetics and evolutionary viewpoints. Mimban landrace of maize is a popular choice in Mizoram as food among the locals due to its stickiness caused by recessive wx1 gene resulting in high amylopectin in the grains. In the present study, a set of 24 Mimban accessions possessing high amylopectin (mean 89.72%, range 80.2–93.7%) content were analyzed. 93 SSRs markers generated a total of 334 alleles with a range of 2–9 and mean of 3.59 alleles per locus. Polymorphism information content varied from 0.117 to 0.829 with an average of 0.528. A total of 20 unique and 24 rare alleles were detected. Twenty-seven major alleles with individual frequencies exceeding 0.70 were also identified across the accessions. Cluster analyses classified 24 genotypes into three major clusters each having 2, 14 and 9 accessions. The clustering pattern was largely congruent with the geographical information. Diverse origin of the accessions was also depicted by the SSR based principal coordinate analysis. These accessions with high amylopectin content from diverse clusters may be crossed to derive heterotic hybrid and also might be used for novel gene identification. Thus information generated here possesses great potential in their utilization in the waxy corn genomics and breeding and emphasizes the need for further exploration of unique trait specific genepool from unexplored areas. This is the first report of molecular characterization of Mimban landrace accessions from NEH region.

Genetic analysis of prolificacy in “Sikkim Primitive”—A prolific maize (Zea mays) landrace of North‐Eastern Himalaya

AbstractProlificacy assumes significance for development of high‐yielding baby corn hybrids. “Sikkim Primitive” is a native landrace of North‐Eastern Himalaya, and is the highest prolific maize germplasm. So far, the genetics of prolificacy in “Sikkim Primitive” has not been deciphered. Here, a prolific inbred (MGU‐SP‐101) developed from “Sikkim Primitive” was crossed with four non‐prolific inbreds viz., LM13, BML7, HKI161 and HKI1128. Six generations (P1, P2, F1, F2, BC1P1 and BC1P2) of the crosses were evaluated at two locations during rainy season 2018. MGU‐SP‐101 possessed 2.50–3.78 ears per plant compared to 1.06–1.86 among non‐prolific inbreds. The variation for ears was the highest in F2s (1–8), followed by BC1P1 (1–7) and BC1P2 (1–5). The quantitative inheritance pattern of prolificacy with prevalence of non‐allelic interactions of duplicate epistasis type has been observed. Dominance × dominance effect was predominant over additive × additive and additive × dominance effects. Total number of major gene blocks ranged from 0.41 to 2.86, thereby suggesting the involvement of at least one major gene/QTL governing the prolificacy. This is the first report of genetic dissection of prolificacy in “Sikkim Primitive”.

Climate change is predicted to disrupt patterns of local adaptation in wild and cultivated maize.

Climate change is one of the most important threats to biodiversity and crop sustainability. The impact of climate change is often evaluated on the basis of expected changes in species' geographical distributions. Genomic diversity, local adaptation, and migration are seldom integrated into future species projections. Here, we examine how climate change will impact populations of two wild relatives of maize, the teosintes Zea mays ssp. mexicana and Z. mays ssp. parviglumis. Despite high levels of genetic diversity within populations and widespread future habitat suitability, we predict that climate change will alter patterns of local adaptation and decrease migration probabilities in more than two-thirds of present-day teosinte populations. These alterations are geographically heterogeneous and suggest that the possible impacts of climate change will vary considerably among populations. The population-specific effects of climate change are also evident in maize landraces, suggesting that climate change may result in maize landraces becoming maladapted to the climates in which they are currently cultivated. The predicted alterations to habitat distribution, migration potential, and patterns of local adaptation in wild and cultivated maize raise a red flag for the future of populations. The heterogeneous nature of predicted populations' responses underscores that the selective impact of climate change may vary among populations and that this is affected by different processes, including past adaptation.

Assessment of potential impacts associated with gene flow from transgenic hybrids to Mexican maize landraces

Genetically modified (GM) maize has been grown and safely consumed on a global scale since its commercialization in 1996. However, questions have been raised about the potential impact that GM maize could have on native maize landraces in Mexico, which is the center of origin and diversity of maize. This research was conducted to evaluate potential changes to maize landraces in an unlikely event of transgene introgression. For this study, two GM traits that confer insect protection and herbicide tolerance in maize (MON 89034 and MON 88017), designated as VT3Pro, were introgressed into two Mexican landraces, Tuxpeño and Tabloncillo. Field trials were conducted across four environments to assess phenotypic characteristics, plant response to stressors, and kernel composition of landraces with and without VT3Pro traits. Furthermore, materials from four backcrossing generations were analyzed for segregation of these GM traits. Generally, no significant differences were observed between landraces with and without VT3Pro traits for the evaluated characteristics and the segregation analysis showed that GM traits, when introgressed into landraces, followed Mendelian principles. These results support the conclusion that, if inadvertently introgressed into landraces, VT3Pro traits are not expected to alter phenotypic or kernel characteristics, plant response to stressors (except for targeted insect protection and herbicide tolerance traits) and would segregate like any endogenous gene. These results should be taken into consideration when discussing benefits and risks associated with commercial production of GM maize hybrids in the centers of origin and diversity of maize.

Temporal dynamics of detected transgenes in maize landraces in their center of origin

espanolEl primer reporte sobre maiz transgenico presente en las variedades nativas en su centro de origen se publico en 2001 para Oaxaca, Mexico. Las investigaciones posteriores realizadas en el mismo estado fueron controvertidas: la mayoria de las muestras de maiz analizadas en el periodo de 2001 a 2004 fueron negativas y solo unas pocas muestras resultaron positivas para la presencia de elementos transgenicos en diferentes localidades y anos. El proposito de este articulo es documentar la presencia de maiz transgenico en las regiones terrestres prioritarias (RTP) de Oaxaca y contribuir a la comprension del movimiento del maiz transgenico a traves de las practicas de manejo de semillas. Durante el periodo 2008-2018, se monitorearon 66 municipios y 148 localidades pertenecientes a 3 RTP. Se encuesto a un total de 1,210 agricultores sobre las practicas de manejo del maiz y se obtuvieron 1,412 muestras de maiz nativo que se analizaron mediante metodos moleculares. La presencia adventicia de secuencias transgenicas se detecto en 1.69% de las muestras. Las muestras positivas provinieron de municipios de la sierra de Juarez, Los Loxicha (sierra Sur) y Santa Maria Huatulco en la costa del Pacifico. Las respuestas de los agricultores indicaron que hay un gran movimiento de semillas entre las localidades, pero tambien se introducen semillas de otras areas del pais. Los datos muestran episodios de aparicion y desaparicion de los transgenes, lo que indica un reemplazo espacio-temporal altamente dinamico a lo largo del tiempo, causado principalmente por la introduccion de material externo. Este ultimo aspecto debe ser tomado en cuenta por las autoridades para la regulacion de la introduccion de semillas mejoradas a las comunidades tradicionales donde las variedades locales son la base de su subsistencia. EnglishThe first report of transgenic maize in Mexico was published in 2001 for Oaxaca, Mexico. Subsequent studies were controversial, because most of the maize samples analyzed from different years and localities, were negative. The purpose of this paper is to publish records of the presence of transgenic maize in Priority Terrestrial Regions in Oaxaca, and to contribute to the understanding of the movement of transgenic maize through seed management practices. During 2008-2018, 66 municipalities and 148 localities, belonging to 3 PTRs were monitored. A total of 1,210 farmers were surveyed on practices associated with maize management, and 1,412 maize samples were obtained and analyzed using molecular methods. Adventitious presence of transgenic sequences was detected in 1.69% of the samples. The positive samples came from municipalities belonging to Sierra Juarez, Los Loxicha region, and Santa Maria Huatulco. Farmers’ responses indicated that there is a high movement of seed among localities, but also from other areas of the country. Transgenes appear and disappear, indicating a highly dynamic spatio-temporal replacement over time, mainly due to introduction of foreign material. This aspect must be taken into account to regulate introduction of improved maize to traditional communities.

Natural variation of hydroxycinnamic acid amides in maize landraces

Maize is a highly relevant source of diverse phytochemicals. While these active compounds with nutraceutical and defensive properties, and their germplasm sources have been elucidated for maize, especially those related to phenolic compounds, some compounds such as hydroxycinnamic acid amides (HCAAs) are poorly studied. In this investigation, the distribution of HCAAs was investigated in 32 Mexican landraces to provide an estimation of the range of variability of HCAA content in maize kernel. Kernel tissues were analysed to localize and quantify these compounds. The variation in HCAAs was also analysed in relation of its eco-geographical origin, distribution and as taxonomic marker. The major compounds determined were diferuloyl putrescine, feruloyl putrescine and cinnamoyl putrescine. Ranges of concentration were detected from 428 to 2336 μg/g for diferuloyl putrescine meanwhile feruloyl putrescine and cinnamoyl putrescine were quantified from 6 to 85 μg/g. A significant correlation (r2 = 0.603, p = 0.018) was found between the maximum altitude of origin of the landrace and the concentration of diferuloyl putrescine in the external grain tissues. This relationship suggests that the maize with high HCAAs content were selected in low altitudes environments under natural selection pressure. Maize landraces are proposed as sources of HCAAs for diverse purposes.

The abandonment of maize landraces over the last 50\xa0years in Morelos, Mexico: a tracing study using a multi-level perspective

Understanding the causes of maize landrace loss in farmers’ field is essential to design effective conservation strategies. These strategies are necessary to ensure that genetic resources are available in the future. Previous studies have shown that this loss is caused by multiple factors. In this longitudinal study, we used a collection of 93 maize landrace accessions from Morelos, Mexico, and stored at the International Maize and Wheat Improvement Center (CIMMYT) Maize Germplasm Bank, to trace back to the original 66 donor families after 50 years and explore the causes for why they abandoned or conserved their seed lots. We used an actor-centered approach, based on interviews and focus group discussions. We adopt a Multi-Level Perspective framework to examine loss as a process, accommodating multiple causes and the interactions among them. We found that the importance of maize landrace cultivation had diminished over the last 50 years in the study area. By 2017, 13 families had conserved a total of 14 seed lots directly descended from the 1967 collection. Focus group participants identified 60 accessions that could still be found in the surrounding municipalities. Our findings showed that multiple interconnected changes in maize cultivation technologies, as well as in maize markets, other crop markets, agricultural and land policies, cultural preferences, urbanization and climate change, have created an unfavorable environment for the conservation of maize landraces. Many of these processes were location- and landrace-specific, and often led to landrace abandonment during the shift from one farmer generation to the next.

Proximate and mineral content of maize landrace (tunu’ana’) from East Nusa Tenggara

Abstract. Murningsih T, Yulita KS, Bora CY, Arsa IGB. 2018. Proximate and mineral content of maize landrace (tunu’ana’) from East Nusa Tengga. Pros Sem Nas Masy Biodiv Indon 5: 107-111. In this study, we carried out analysis of the proximate and mineral content of maize landrace (tunu’ana’ ) based on the method recommended by AOAC (Association of Official Analytical Chemists). Three superior varieties (Piet Kuning, Gumarang and Lamuru) are used as a standard comparison. The proximate analysis results showed that tunu'ana' contained water (10.49±0.01%), ash (1.45±0.01%), protein (11.78±0.05%), fat (5, 59±0.22%), crude fiber (6.84±0.07%), total carbohydrate (70.69±0.21%) and energy (380.19±1.56 kcal / 100g) based on dry weight. The results of mineral analysis showed that the tunu'ana' contained magnesium 127.50±0.00 mg, iron (7.19±0.67 mg), calcium (11.50±0.01 mg), potassium (310.00±0.01 mg), phosphorus (450.00±0.00 mg), copper (40.20±0.45 mg), manganese (0.669±0.23 mg) and zinc (3.29±0.61 mg) per 100 g of dry weight. Based on the results of the analysis, it was shown that the tunu'ana' contained higher nutrients and minerals than the three superior varieties but the highest water (12.05±0.01%) and calcium content (19.50±0.01) mg / 100g were in Lamuru, while the highest carbohydrate (12.05±0.01%) was in Gumarang.

Testcross performance of doubled haploid lines from European flint maize landraces is promising for broadening the genetic base of elite germplasm.

Selected doubled haploid lines averaged similar testcross performance as their original landraces, and the best of them approached the yields of elite inbreds, demonstrating their potential to broaden the narrow genetic diversity of the flint germplasm pool. Maize landraces represent a rich source of genetic diversity that remains largely idle because the high genetic load and performance gap to elite germplasm hamper their use in modern breeding programs. Production of doubled haploid (DH) lines can mitigate problems associated with the use of landraces in pre-breeding. Our objective was to assess in comparison with modern materials the testcross performance (TP) of the best 89 out of 389 DH lines developed from six landraces and evaluated in previous studies for line per se performance (LP). TP with a dent tester was evaluated for the six original landraces, ~ 15 DH lines from each landrace selected for LP, and six elite flint inbreds together with nine commercial hybrids for grain and silage traits. Mean TP of the DH lines rarely differed significantly from TP of their corresponding landrace, which averaged in comparison with the mean TP of the elite flint inbreds ~ 20% lower grain yield and ~ 10% lower dry matter and methane yield. Trait correlations of DH lines closely agreed with the literature; correlation of TP with LP was zero for grain yield, underpinning the need to evaluate TP in addition to LP. For all traits, we observed substantial variation for TP among the DH lines and the best showed similar TP yields as the elite inbreds. Our results demonstrate the high potential of landraces for broadening the narrow genetic base of the flint heterotic pool and the usefulness of the DH technology for exploiting idle genetic resources from gene banks.

Nematode communities differ in Hopi landrace maize and commercial maize

Selection pressures of crop breeding in varying abiotic contexts may produce cultivars differing in their relationships with belowground organisms. Nematode assemblages associated with a Hopi maize (Zea mays L.) landrace and two commercial maize varieties were examined at three traditional farms (two irrigated, one dry-farmed) near the village of Moenkopi on the Hopi Reservation in Arizona, U.S.A. At each farm, the landrace and one commercial maize variety were cultivated in close proximity. Within the two irrigated farms, densities of free-living nematodes, but not plant parasitic nematodes, were higher in landrace plots compared to commercial variety plots; however, at the dry-farmed site the nematode assemblages associated with the two maize varieties did not differ. Nonmetric multidimensional scaling (NMDS) and multiple response permutation procedure (MRPP) showed that at the irrigated farms, nematode assemblages associated with landrace maize differed significantly from those associated with commercial maize in analyses based on functional guilds, feeding groups and non-phytoparasitic c-p groups. Assemblages at the dry-farmed site were different from those at the irrigated sites in community composition based on morphotypes, functional guilds, and feeding groups, but were similar to the irrigated commercial variety plots based on c-p groups. Nematode abundances were likely constrained by water availability at the dry-farmed site, but at the irrigated sites, nematode community dissimilarities between the landrace and the commercial maize variety may have resulted from differences in plant-soil microbe interactions for the two crop varieties. Selection pressures associated with Hopi agroecosystems might have produced landraces with different belowground allocation strategies than commercial crop varieties selected under high resource conditions.

The genetic architecture of teosinte catalyzed and constrained maize domestication

The process of evolution under domestication has been studied using phylogenetics, population genetics-genomics, quantitative trait locus (QTL) mapping, gene expression assays, and archaeology. Here, we apply an evolutionary quantitative genetic approach to understand the constraints imposed by the genetic architecture of trait variation in teosinte, the wild ancestor of maize, and the consequences of domestication on genetic architecture. Using modern teosinte and maize landrace populations as proxies for the ancestor and domesticate, respectively, we estimated heritabilities, additive and dominance genetic variances, genetic-by-environment variances, genetic correlations, and genetic covariances for 18 domestication-related traits using realized genomic relationships estimated from genome-wide markers. We found a reduction in heritabilities across most traits, and the reduction is stronger in reproductive traits (size and numbers of grains and ears) than vegetative traits. We observed larger depletion in additive genetic variance than dominance genetic variance. Selection intensities during domestication were weak for all traits, with reproductive traits showing the highest values. For 17 of 18 traits, neutral divergence is rejected, suggesting they were targets of selection during domestication. Yield (total grain weight) per plant is the sole trait that selection does not appear to have improved in maize relative to teosinte. From a multivariate evolution perspective, we identified a strong, nonneutral divergence between teosinte and maize landrace genetic variance-covariance matrices (G-matrices). While the structure of G-matrix in teosinte posed considerable genetic constraint on early domestication, the maize landrace G-matrix indicates that the degree of constraint is more unfavorable for further evolution along the same trajectory.

New Waxy allele wx-Reina found in Chinese waxy maize

Waxy gene mutations cause the stickiness of maize grains. China is rich in waxy maize landraces and is considered to be the origin of waxy maize. At present, the Waxy alleles found in Chinese waxy maize include wx-D7, wx-D10, wx-Cin4, and wx-124, of which wx-Cin4 and wx-124 are characterized as transposon insertion mutations. The Yunnan area has the most abundant Chinese waxy maize; however, there are still a large number of waxy maize landraces with unknown Waxy alleles. In this study, 20 waxy maize landraces from Yunnan Province of China were used as research materials for waxy gene analysis, and a new Waxy allele was detected. Molecularly, this allele is characterized by an ~ 5.4-Kb retrotransposon Reina inserted in the tenth intron of the Waxy gene, and we named this allele wx-Reina. Reina is a member of the long terminal repeat (LTR) retrotransposon family. This Reina transposon has the same LTR sequence at both ends, so this mutation is a newly formed mutation. Through reverse transcription PCR (RT-PCR) analysis, we found that Reina insertion results in the deletion of exons 10 and 11 in the transcript of wx-Reina, so its original gene function is lost. The discovery of wx-Reina further enriches the knowledge of types of waxy alleles in Chinese waxy maize. Combined with our previous studies, we believe that transposon activity is one of the main driving forces for the formation of Waxy gene alleles in Chinese waxy maize.

Characterization of Open-Pollinated Maize Varieties from Rio Grande do Sul State

The morphological characterization allows one to estimate and evaluate the genetic distance among different varieties, identifying heterotrophic groups by means of clustering methods. The objectives of the study were to characterize improved open-pollinated varieties (VPAs) and maize landraces based on the main quantitative agronomic traits and to estimate the variability and similarity between them. Sixteen maize varieties from the southern region of the State of Rio Grande do Sul, Brazil were evaluated. Data were subjected to analysis of variance. For the characterization, the Tukey averages comparison test was performed. The similarity among the varieties was tested using the Tocher optimization method. The differences detected indicate the presence of genetic variability among the studied varieties. According to the Tocher grouping, it was found that some populations have the potential to be selected as parents in breeding programs, maximizing the variability obtained from their crosses. For certain traits, maize landraces do not differ from improved varieties and show high similarity.

Landrace maize varieties differ from conventional and genetically modified hybrid maize in response to inoculation with arbuscular mycorrhizal fungi.

Land area planted with genetically modified (GM) crops has grown rapidly, and Brazil has the second largest area with those plants. There is, however, limited information on the possible effects of that technology on non-target organisms, especially root symbionts, such as arbuscular mycorrhizal fungi (AMF). We evaluated AMF symbiosis development in five maize genotypes: one landrace, two conventional hybrids (DKB 240 and Formula), and two GM hybrids (DKB 240-VT Pro and Formula TL). We evaluated symbiosis response in two separate experiments: one in autumn and the other in summer. Plants were inoculated with Rhizophagus clarus (Rc) and Gigaspora margarita (Gm) and compared to plants without inoculation. We evaluated root colonization, spore number, and plant biomass and phosphorous accumulation 30 and 60days after inoculation. There were no consistent effects of GM crops, but AMF species and maize genotype affected symbiosis development. Formula genotype (isoline and GM) had a negative response to inoculation, with a decrease of around 30% in biomass and P concentration in Rc-inoculated plants. The maize landrace had a positive response, with increases of 17% and 14% in the same variables. DKB genotype (isoline and GM) showed negative, positive, and neutral effects. The results show that plant genetic identity is a determinant factor in symbiosis performance, suggesting that plants selected in low P availability can make better use of mycorrhizal symbiosis. Given the role that AMF play in different ecosystem processes, use of landrace maize may contribute to agrobiodiversity conservation.

Quality Parameters of Masa and Tortillas Produced from Blue Maize (Zea mays sp. mays) Landraces.

There is increasing interest in the production of landrace blue maize varieties for the production of traditional foods and for specialty (noncommodity) products. Most varieties have soft (floury) endosperm and their suitability for thermo-alkaline processing is not known. We examined the physical and functional properties of eight floury varieties with those of three dent and one flint variety for masa and tortilla production. Results revealed high variability in physical properties of kernels. Significant differences (P < 0.05) were observed in kernel, flour, masa, and tortilla color. The softer kernels of blue maize varieties had lower (P < 0.05) cooking times during nixtamalization than those of denser kernels. The results showed variation among varieties (P < 0.05) in the kernel, masa, tortilla hardness, as well as in extensibility of the tortillas. Nixtamalization affected (P < 0.05) masa color, resulting in reduced yellow and reddish tones. The gelatinization temperature was the same (P > 0.05) in all studied landraces for the flour and the masa. The enthalpy was affected (P < 0.05) by the landrace analyzed for starch gelatinization (P > 0.05). The landraces studied showed similar (P > 0.05) starch gelatinization and denaturation temperatures. The storage modulus (G'), loss modulus (G''), and the temperature (TG') of flour and masa-dough were different (P < 0.05) among different varieties. Southwestern floury varieties can be cooked during nixtamalization for shorter periods than flint and dent varieties to obtain comparable tortilla quality. PRACTICAL APPLICATION: Southwestern blue floury maize varieties are suitable for nixtamalized tortilla production. Variation between varieties was observed for quality parameters. Floury varieties require shorter cooking time but it is recommended that nixtamalization parameters be optimized.

A LEA Gene from a Vietnamese Maize Landrace Can Enhance the Drought Tolerance of Transgenic Maize and Tobacco

Maize (Zea mays) is a major cereal crop worldwide, and there is increasing demand for maize cultivars with enhanced tolerance to desiccation. Late embryogenesis abundant (LEA) proteins group 5C is involved in plants’ responses to various osmotic stresses such as drought and salt. A putative group 5C LEA gene from Z. mays cv. Tevang 1 was isolated, named ZmLEA14tv, and cloned into a T-DNA for expression in plants. The deduced amino acid of ZmLEA14tv showed a conserved Pfam LEA_2 domain and a high proportion of hydrophobic residues, characteristic of group 5C LEA proteins. Transgenic tobacco and maize plants expressing ZmLEA14tv were generated. During drought simulation conditions, the ZmLEA14tv-expressing plants of tobacco showed improved recovery ability, while those of maize enhanced the seed germination in comparison with the non-transgenic control plants. In addition, the survival rate of ZmLEA14tv transgenic maize seedlings was twice as high as the control. These results indicated that ZmLEA14tv might be involved in the drought tolerance of plants and could be a candidate gene for developing enhanced drought-tolerant crops.

Kernel properties and popping potential of Chapalote, a Mexican ancient native maize

Chapalote is a Mexican ancient maize landrace with popping characteristics that have not been studied. This work aimed to study the kernel physicochemical properties and their relationship with popping properties of 10 Chapalote accessions. Two popping methods, cooking pan and hot-air popping, were tested. A commercial popcorn sample was used for comparison purposes. Hot-air popping led to higher expansion volume, less unpopped kernels, and bigger popped kernels than traditional popping. Among Chapalote samples, one accession (612) had the best popping properties, but none of them popped similarly to the commercial popcorn. This behavior may be related to the non-breeding origin of Chapalote accessions contrasting with the improved hybrids. Smaller kernels containing more pedicel, pericarp, and vitreous endosperm led to higher expansion volume and lower unpopped kernels. In air-popping, higher α-zein content, and bigger starch granules with less crystallinity influenced positively the popping properties, mainly the air bubbles and popped kernel size. Pericarp thickness was not a crucial factor in popping performance. Some Chapalote accessions with good popping quality could be an important source of germplasm in breeding programs for the development of modern popcorn varieties with distinct properties, which may help to avoid the extinction of this landrace.

Detecting Adaptive Differentiation in Structured Populations with Genomic Data and Common Gardens.

Adaptation in quantitative traits often occurs through subtle shifts in allele frequencies at many loci-a process called polygenic adaptation. While a number of methods have been developed to detect polygenic adaptation in human populations, we lack clear strategies for doing so in many other systems. In particular, there is an opportunity to develop new methods that leverage datasets with genomic data and common garden trait measurements to systematically detect the quantitative traits important for adaptation. Here, we develop methods that do just this, using principal components of the relatedness matrix to detect excess divergence consistent with polygenic adaptation, and using a conditional test to control for confounding effects due to population structure. We apply these methods to inbred maize lines from the United States Department of Agriculture germplasm pool and maize landraces from Europe. Ultimately, these methods can be applied to additional domesticated and wild species to give us a broader picture of the specific traits that contribute to adaptation and the overall importance of polygenic adaptation in shaping quantitative trait variation.

Assessing Genetic Diversity in Romanian Maize Landraces, Using Molecular Markers

The evaluation of morphological differences is a traditional method of evolutionary and pedigree relationship determination. It was particularly useful in maize, where phenotypic differences occur (e.g. colour, kernel type and kernel size) (Murariu et al., 2002). However, only molecular markers provide information that is independent of environmental influences or of plant development phase. Therefore, techniques of DNA analysis have become more and more important. Methods based on polymerase chain reaction - PCR - are used widely in research. One of the used methods is the RAPD method (Randomly Amplified Polymorphic DNA) (Beebe et al., 2000). Our aim was to determine the genetic variability existing among maize landraces coming from western part of Romania and to adapt a method for their distinguishing. The use of molecular characterization has allowed the study of diversity within these accessions and the investigation of genetic relationships among them, revealing a wide genetic diversity in this set of 60 accessions, having a highest genetic diversity; they belong to different groups and could be used as base populations for future breeding programs.

The Cluster and Principal Component Analyses of Maize Landraces of Manipur, India

The Cluster and Principal Component Analyses of Maize Landraces of Manipur, India