A genomic journey across the past, present, and future of South American maize.

Maize (Zea mays ssp. mays) diverged from one of its wild relatives, the teosinte Zea mays ssp. parviglumis, in the lowlands of southwest Mexico approximately 9000 years ago. Following this divergence, maize rapidly expanded throughout the Americas, becoming a staple food. This dispersal was accompanied by significant demographic and selective changes, leading to the development of numerous local varieties with a complex evolutionary history that remains incompletely understood. In recent years, genomic advances have challenged traditional models of maize domestication and spread to South America. At least three distinct genetic lineages associated with different migratory waves have been described: ancestral Andean, ancestral Lowland, and Pan-American. Additionally, the significant role of the teosinte Zea mays ssp. mexicana, in the evolution of modern maize has been recently uncovered. Genomic studies have shed light into highland adaptation processes, revealing largely independent adaptation events in Meso- and South America. As new evidence emerges, the regional complexity underlying maize diversity and the need for comprehensive, multi-scale approaches become evident. In the face of climate change and evolving agricultural landscapes, the conservation of native maize in South America is of growing interest, with genomics serving as an invaluable tool for identifying and preserving the genetic variability of locally adapted germplasm.

Diversity of vegetable landraces in the Pampa biome of Brazil and Uruguay: utilization and conservation strategies.

The historical meeting between originally American people, European colonizers, and slaved peoples from Africa in the biome Pampa in South Brazil and Uruguay involved a cultural syncretism and a great genetic diversity of landraces of cultivated species. Genetic richness evolved by selection and cultural processes in response to different environments, cultural backgrounds, and needs. This review summarized the knowledge on vegetable and maize landraces in South Brazilian and Uruguayan Pampa biome, to design a strategy towards the rediscovery, conservation, and sustainable use. Landraces diversity maintained in situ and ex situ is described, specific case studies are presented, and the main problems and tools towards landraces re-valorization are discussed. We show that traditional family farming systems maintain diverse vegetable species, mainly squashes (Cucurbita spp.), sweet potato (Ipomoea batatas), beans (Phaseolus spp.), onion (Allium cepa), peppers (Capsicum spp.), tomato (Solanum lycopersicum), next to leafy vegetables and maize, among others. We propose the priority of systematic surveys as a basis for monitoring genetic erosion, increasing complementariness between in situ and ex situ conservation, and implementing sustainable conservation and utilization. The case studies highlight genetic diversity within each cultivated species, with different crop physiological responses; disease resistances, different quality traits and associated uses, from animal feeding in maize to a range of culinary uses linked to traditional culture in maize and vegetable species, and ornamental uses of specific Capsicum and Cucurbita. Some landraces were the basis for breeding, where improved cultivars allowed the competitiveness of landrace germplasm in the markets. Renewed industrialized products allowed the competitive and sustainable use of Capsicum landraces in Brazilian farmers communities. Strategies towards in situ conservation improvements and valorization are discussed; emphasizing the role played by agroecology, community seed banks and custodian farmers, participatory plant breeding, promotion of landraces specialties among consumers, and the need of research and capacity building, among others. Farmers' participation in the decisions is a key factor, along with the academia and the public sector. Landraces and associated knowledge are treasures to be used to benefit from farmers to consumers, directing the course of agriculture towards sustainable directions.

Nitrogen sources differentially affect respiration, growth, and carbon allocation in Andean and Lowland ecotypes of Chenopodium quinoa Willd.

Chenopodium quinoa Willd. is a native species that originated in the High Andes plateau (Altiplano) and its cultivation spread out to the south of Chile. Because of the different edaphoclimatic characteristics of both regions, soils from Altiplano accumulated higher levels of nitrate (NO3-) than in the south of Chile, where soils favor ammonium (NH4 +) accumulation. To elucidate whether C. quinoa ecotypes differ in several physiological and biochemical parameters related to their capacity to assimilate NO3- and NH4 +, juvenile plants of Socaire (from Altiplano) and Faro (from Lowland/South of Chile) were grown under different sources of N (NO3- or NH4 +). Measurements of photosynthesis and foliar oxygen-isotope fractionation were carried out, together with biochemical analyses, as proxies for the analysis of plant performance or sensitivity to NH4 +. Overall, while NH4 + reduced the growth of Socaire, it induced higher biomass productivity and increased protein synthesis, oxygen consumption, and cytochrome oxidase activity in Faro. We discussed that ATP yield from respiration in Faro could promote protein production from assimilated NH4 + to benefit its growth. The characterization of this differential sensitivity of both quinoa ecotypes for NH4 + contributes to a better understanding of nutritional aspects driving plant primary productivity.

Nutritional assessment of nixtamalized maize tortillas produced from dry masa flour, landraces, and high yield hybrids and varieties.

In the scientific literature there are different analyses of the nutritional profiles of maize tortillas, whether they are landraces or hybrid maize versus those made with dry masa flour (DMF). In general terms, there is agreement in the reported content of moisture. However, for the other nutrients, a great disparity is reported for each type of tortilla which may be due to various factors such as the type of maize or processing methods. In this study, the nutritional aspects of maize tortillas made with different genotypes (five hybrids, two varieties, five landraces, six hybrid mixtures and six dry masa flours) under controlled conditions, were compared. More than 30 characteristics were analyzed. High performance hybrids and varieties (HPHV) and landraces had the highest (p < 0.05) antioxidant capacity (58.8% free, 150.2% bound). In terms of vitamins contents, the tortillas produced from DMF contained 11.2 and 3.5 times more B1, 18.6 and 7.8 times more B2, and 2.7 and 5.3 times more B3 than HPHV and landraces respectively; and only in these samples was detected folic acid. DMF tortilla samples contained 1.75 times more sodium and 2.75 times more iron than the other groups, and 0.75 times less calcium than HPHV. Zinc was present in higher concentration (p < 0.05) in DMF tortilla samples. The landraces had the highest protein content (average 10.28%), but the tortillas produced from DMF presented the highest protein quality evaluated by protein digestibility-corrected amino acid score (PDCAAS) (p < 0.05) that represents 27, 25 and 19% more than hybrids mixture, HPHV and landraces, respectively. This work gives valuable information on how different types of grains differ in the nutritional quality affecting the final product to provide more elements in the decision-making of processors. There is no a perfect maize, but there are genotypes that can be combined as mixtures and the processing method to design superior nutritional tortillas and related products for populations that highly consume them and improve their human health.

Large scale sampling of Mexican maize landraces for the presence of transgenes.

The presence and levels of transgenic maize in Mexico and the effect this could have on local landraces or closely related species such as teosinte has been the subject of several previous reports, some showing contrasting results. Cultural, social and political factors all affect maize cultivation in Mexico and although since 1998 there has been a moratorium on the commercial cultivation of transgenic maize, Mexico imports maize, mainly from the USA where transgenic cultivars are widely grown. Additionally extensive migration between rural areas in Mexico and the USA and customs of seed exchange between farmers may also play an unintentional role in the establishment of transgenic seed. A comprehensive study of all Mexican maize landraces throughout the country is not feasible, however this report presents data based on analysis of 3204 maize accessions obtained from the central region of Mexico (where permits have never been authorized for cultivation of transgenic maize) and the northern region (where for a short period authorization for experimental plots was granted). The results of the study confirm that transgenes are present in all the geographical areas sampled and were more common in germplasm obtained in the northern region. However, there was no evidence that regions where field trials had been authorized showed higher levels of transgene presence or that the morphology of seed lots harboring transgenic material was significantly modified in favor of expected transgenic phenotypes.

Quality assessment of maize tortillas produced from landraces and high yield hybrids and varieties.

Introduction: Different analyses of the profiles of tortillas have been made using the traditional method, whether from landraces or hybrids versus those made with dry masa flour in which significant variability (p < 0.05) is reported in favor or against each type of tortilla which may be due to various factors such as the type of maize or the processing methods. Methods: Twenty-two samples including hybrids, hybrid mixtures, varieties, landraces and dry masa flours were processed to masa and tortilla under similar and controlled conditions and tortilla quality evaluated. In total, 70 characteristics were analyzed as physicochemical properties of the maize (e.g., hectoliter weight and dimensions), processability characteristics, masa characteristics [e.g. viscoamylographic parameters (RVA)], and quality parameters of tortillas (e.g., sensory performance, color and texture). Results and discussión: The studied materials presented variability among genotypes, especially within landraces. The physical and chemical properties of corn affected the processability and quality characteristics of tortillas (sensory and composition), and it was found that high producing hybrids and varieties (p < 0.05) were better and more consistent in all stages of processing. Forty percent of the landraces yielded masa with poor machinability. Conclusion: Landraces averaged 1.27 percentage points more protein (p < 0.05) than other analyzed samples and they comparatively yielded tortillas with lower extensibility (12.34%) compared to counterparts produced from hybrids and varieties. This work provides valuable information on how the chemical and physical characteristics of different types of maize genotypes affect the nixtamalization process and the quality of tortillas to provide more elements in the selection of the most appropriate genotypes for tortilla production.

In search of better snacks: ohmic-heating nixtamalized flour and amaranth addition increase the nutraceutical and nutritional potential of vegetable-enriched tortilla chips.

BACKGROUND: Nixtamalized flour snacks such as tortilla chips are widely consumed across the world, but they are nutritionally poor and contribute to obesity and other non-communicable diseases. The production of healthy versions of such snacks, by incorporating vegetables and improving the quality of the flours used in their formulation, could help address these nutritional challenges. This study compared the fortification of baked tortilla chips with vegetable leaf powders (kale and wild amaranth at 0%, 4%, 8%, and 16% w/w) and using two types of nixtamalized flour: traditional (TNF) and with ohmic heating (OHF). RESULTS: Overall, the use of OHF increased 1.88 times the fibre in enriched and non-enriched snacks with respect to TNF, but the latter had 1.85 times more protein. Addition of 16% of vegetable powders increased protein (kale = 1.4-fold; amaranth = 1.3-fold) and dietary fibre (kale = 1.52-fold; amaranth = 1.7-fold). Amaranth enrichment improved total phenolic content (TPC) and total flavonoid content (TFC) of chips at least 1.2 and 1.63 times, respectively. OHF chips also had higher bound TPC than TNF ones, regardless of vegetable addition. Combinations of OHF with 16% amaranth produced chips 1.74-fold higher in antioxidant capacity than non-enriched ones, due to increased content of phenolics such as ferulic acid. CONCLUSION: This work showed that tortilla chips made using nixtamalized flour produced with assisted ohmic heating, alone or in combination with wild amaranth leaf powder, could be used in the production of healthy maize snacks to enhance their prospective antioxidant activity and nutritional value. © 2023 Society of Chemical Industry.

Effect of Storage Technologies on Postharvest Insect Pest Control and Seed Germination in Mexican Maize Landraces.

Smallholder farmers who grow maize landraces face important challenges to preserve their seed biodiversity from one season to another. This study was carried out in the central highlands of Mexico to compare the effectiveness of two seed storage practices-specifically, polypropylene woven bags (farmers' conventional practice) vs. hermetic containers-for minimizing seed losses and maintaining germination. Four Mexican landraces were stored for three and six months. Data on moisture content and kernel damage were collected at the beginning and the end of the storage period. Pest-free samples collected were also analyzed for seed germination. Moisture content was below 13% overall and was not significantly affected by storage technology or storage time. Samples from the polypropylene woven bags suffered significant damage from Sitophilus zeamais and Prostephanus truncatus, with the percentages of insect damage and weight loss reaching 61.4% and 23.4%, respectively. Losses were minimal in seed stored in hermetic containers, with a maximum insect damage of 4.1% and weight loss of 2.2%. Overall, the germination rate of samples stored in these airtight containers was greater than 90%. This study provides additional evidence on the effectiveness of hermetic containers at maintaining Mexican landraces' seed quantity and quality during storage in smallholder conditions in central Mexico.

Causes and consequences of DNA content variation in Zea / Causas y consecuencias de la variación del contenido de ADN en Zea

ABSTRACT Cytogenetic evidence indicates that Zea, which comprises maize (Z. mays ssp. mays) and its wild relatives, is an allopolyploid genus. Our research group has carried out numerous cytogenetic studies on Zea species, mainly focused on native Argentinian and Bolivian maize landraces. We found a wide inter- and intraspecific genome size variation in the genus, with mean 2C-values ranging between 4.20 and 11.36 pg. For the maize landraces studied here, it varied between 4.20 and 6.75 pg. The objectives of this work are to analyze the causes of genome size variation and to discuss their adaptive value in Zea. This variation is mainly attributed to differences in the heterochromatin located in the knobs and to the amount of interspersed DNA from retrotransposons. Polymorphisms in presence or absence of B-chromosomes (Bs) and the population frequency of Bs are also a source of genome size variation, with doses ranging between one and eight in the landraces analyzed here. Correlation analysis revealed that the percentage of heterochromatin is positively correlated with genome size. In addition, populations cultivated at higher altitudes, which are known to be precocious, have smaller genome sizes than do those growing at lower altitudes. This information, together with the positive correlation observed between the length of the vegetative cycle and the percentage of heterochromatin, led us to propose that it has an adaptive role. On the other hand, the negative relationship found between Bs and heterochromatic knobs allowed us to propose the existence of an intragenomic conflict between these elements. We hypothesize that an optimal nucleotype may have resulted from such intranuclear conflict, where genome adjustments led to a suitable length of the vegetative cycle for maize landraces growing across altitudinal clines.

RESUMEN La evidencia citogenética indica que el género Zea, el maíz (Z. mays ssp. mays) y sus parientes silvestres, posee un origen alopoliploide. Nuestro grupo de investigación ha realizado numerosos estudios en especies de Zea, principalmente en maíces nativos de Argentina y Bolivia. En este género, hallamos una amplia variación inter e intraespecífica en el tamaño del genoma, con valores 2C medios que oscilan entre 4,20 y 11,36 pg. El valor 2C medio de los maíces nativos estudiados varió entre 4,20 y 6,75 pg. Los objetivos de este trabajo son analizar las causas de la variación del tamaño del genoma en Zea y discutir su valor adaptativo. Esta variación se atribuye principalmente a las diferencias en la heterocromatina de los knobs y en la cantidad de ADN intercalado de los retrotransposones. Otras fuentes de variación son los polimorfismos para presencia/ausencia de cromosomas B (Bs) y para la frecuencia poblacional de Bs en las razas analizadas, con dosis que oscilan entre uno y ocho Bs. El porcentaje de heterocromatina se correlaciona positivamente con el tamaño del genoma. Las poblaciones cultivadas en altitudes altas, que son precoces, tienen tamaños de genoma más pequeños que las que crecen en bajas altitudes. Esta información, junto con la correlación positiva observada entre la duración del ciclo vegetativo y el porcentaje de heterocromatina, nos llevó a proponer el rol adaptativo de la heterocromatina. Por otro lado, la relación negativa encontrada entre Bs y knobs heterocromáticos nos permitió proponer la existencia de un conflicto intragenómico entre estos elementos. Hipotetizamos que de este conflicto intranuclear habría resultado el nucleotipo óptimo, donde ajustes genómicos condujeron a una duración adecuada del ciclo vegetativo en las razas de maíz que crecen a lo largo de clines altitudinales.

Worldwide Selection Footprints for Drought and Heat in Bread Wheat (Triticum aestivum L.).

Genome-environment Associations (GEA) or Environmental Genome-Wide Association scans (EnvGWAS) have been poorly applied for studying the genomics of adaptive traits in bread wheat landraces (Triticum aestivum L.). We analyzed 990 landraces and seven climatic variables (mean temperature, maximum temperature, precipitation, precipitation seasonality, heat index of mean temperature, heat index of maximum temperature, and drought index) in GEA using the FarmCPU approach with GAPIT. Historical temperature and precipitation values were obtained as monthly averages from 1970 to 2000. Based on 26,064 high-quality SNP loci, landraces were classified into ten subpopulations exhibiting high genetic differentiation. The GEA identified 59 SNPs and nearly 89 protein-encoding genes involved in the response processes to abiotic stress. Genes related to biosynthesis and signaling are mainly mediated by auxins, abscisic acid (ABA), ethylene (ET), salicylic acid (SA), and jasmonates (JA), which are known to operate together in modulation responses to heat stress and drought in plants. In addition, we identified some proteins associated with the response and tolerance to stress by high temperatures, water deficit, and cell wall functions. The results provide candidate regions for selection aimed to improve drought and heat tolerance in bread wheat and provide insights into the genetic mechanisms involved in adaptation to extreme environments.

Simple Sequence Repeat Markers Reveal Genetic Diversity and Population Structure of Bolivian Wild and Cultivated Tomatoes (Solanum lycopersicum L.).

The western part of South America is a centre of diversity for tomatoes, but genetic diversity studies are lacking for parts of that region, including Bolivia. We used 11 simple sequence repeat (SSR) markers (including seven novel markers) to evaluate genetic diversity and population structure of 28 accessions (four modern cultivars, four advanced lines, nine landraces, 11 wild populations), and to compare their genetic variation against phenotypic traits, geographical origin and altitude. In total, 33 alleles were detected across all loci, with 2-5 alleles per locus. The top three informative SSRs were SLM6-11, LE20592 and TomSatX11-1, with polymorphism information content (PIC) of 0.65, 0.55 and 0.49, respectively. The genetic diversity of Bolivian tomatoes was low, as shown by mean expected heterozygosity (He) of 0.07. Analysis of molecular variance (AMOVA) revealed that 77.3% of the total variation was due to variation between accessions. Significant genetic differentiation was found for geographical origin, cultivation status, fruit shape, fruit size and growth type, each explaining 16-23% of the total variation. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) tree and principal coordinate analysis (PCoA) scatter plot both revealed differentiation between accessions with determinate flowers and accessions with indeterminate flowers, regardless of cultivation status. The genetic profiles of the accessions suggest that the Bolivian tomato gene pool comprises both strictly self-pollinating and open-pollinating genotypes.

Genomic Insights into Cultivated Mexican Vanilla planifolia Reveal High Levels of Heterozygosity Stemming from Hybridization.

Although vanilla is one of the most valuable spices, there is a lack of understanding of the genomic variability of the main vanilla producing species, Vanilla planifolia, within its cultivated origin, Mexico. High genomic heterozygosity levels within the globally cultivated 'Daphna' genome have raised questions on the possibility of a hybrid origin and analogous genomic signatures of vanilla cultivated within its origin. This study investigated these questions by assessing whether the genomic structure of Mexican V. planifolia reflected domestication events. Whole genome re-sequencing was used to compare genome complexity between 15 cultivated accessions from different regions and gene pools. Results showed high levels of heterozygosity, ranging from 2.48% to 2.85%, in all but one accession, which exhibited a low level (0.403%). Chromosome-level comparative analyses revealed genomic variability among samples, but no signals of chromosome rearrangements. These findings support the hypotheses that cultivated vanilla resulted from hybridization and that multiple domestication events have shaped cultivated vanilla leading to the formation of landraces. High cultural diversity within this region further supports the occurrence of multiple domestication processes. These results may help to improve breeding and conservation efforts aiming to preserve the genetic diversity of this beloved spice threatened by climate change.

Genome-Environment Associations, an Innovative Tool for Studying Heritable Evolutionary Adaptation in Orphan Crops and Wild Relatives.

Leveraging innovative tools to speed up prebreeding and discovery of genotypic sources of adaptation from landraces, crop wild relatives, and orphan crops is a key prerequisite to accelerate genetic gain of abiotic stress tolerance in annual crops such as legumes and cereals, many of which are still orphan species despite advances in major row crops. Here, we review a novel, interdisciplinary approach to combine ecological climate data with evolutionary genomics under the paradigm of a new field of study: genome-environment associations (GEAs). We first exemplify how GEA utilizes in situ georeferencing from genotypically characterized, gene bank accessions to pinpoint genomic signatures of natural selection. We later discuss the necessity to update the current GEA models to predict both regional- and local- or micro-habitat-based adaptation with mechanistic ecophysiological climate indices and cutting-edge GWAS-type genetic association models. Furthermore, to account for polygenic evolutionary adaptation, we encourage the community to start gathering genomic estimated adaptive values (GEAVs) for genomic prediction (GP) and multi-dimensional machine learning (ML) models. The latter two should ideally be weighted by de novo GWAS-based GEA estimates and optimized for a scalable marker subset. We end the review by envisioning avenues to make adaptation inferences more robust through the merging of high-resolution data sources, such as environmental remote sensing and summary statistics of the genomic site frequency spectrum, with the epigenetic molecular functionality responsible for plastic inheritance in the wild. Ultimately, we believe that coupling evolutionary adaptive predictions with innovations in ecological genomics such as GEA will help capture hidden genetic adaptations to abiotic stresses based on crop germplasm resources to assist responses to climate change. "I shall endeavor to find out how nature's forces act upon one another, and in what manner the geographic environment exerts its influence on animals and plants. In short, I must find out about the harmony in nature" Alexander von Humboldt-Letter to Karl Freiesleben, June 1799.

Maize dispersal patterns associated with different types of endosperm and migration of indigenous groups in lowland South America.

BACKGROUND AND AIMS: The lowlands of South America appear to be remarkably important in the evolutionary history of maize, due to new evidence that suggests that maize dispersed from Mexico and arrived in this region in a state of partial domestication. This study aimed to identify dispersal patterns of maize genetic diversity in this part of the continent. METHODS: A total of 170 maize accessions were characterized with 4398 single nucleotide polymorphisms (SNPs) and analysed to determine if maize dispersal was associated with types of endosperm and indigenous language families. KEY RESULTS: Four genetic groups were identified in the discriminant analysis of principal components and five groups in the cluster analysis (neighbour-joining method). The groups were structured according to the predominance of endosperm types (popcorn, floury, flint/semi-flint). Spatial principal component analysis of genetic variation suggests different dispersal patterns for each endosperm type and can be associated with hypotheses of expansions of different indigenous groups. CONCLUSIONS: From a possible origin in Southwestern Amazonia, different maize dispersal routes emerged: (1) towards Northern Amazonia, which continued towards the Caatinga and south-eastern Atlantic Forest (Floury); (2) towards Southern Brazil, passing through the Cerrado and Southern Atlantic Forest reaching the Pampa region (Floury); and (3) along the Atlantic Coast, following Tupi movements originating from two separate expansions: one (Tupinamba) from north to south, and the other (Guarani) in the opposite direction, from south to north (flint, floury and popcorn).

Water Shortage Affects Vegetative and Reproductive Stages of Common Bean (Phaseolus vulgaris) Chilean Landraces, Differentially Impacting Grain Yield Components.

Water availability for agricultural use is currently a global problem that worsens with climate change in several regions of the world. Among grain legumes, common bean (Phaseolus vulgaris) is the most cultivated in the worldwide. The Chilean germplasm of common bean is characterized by tolerance to water stress. Here, we analyzed a selection of nine ancient Chilean landraces in regard to their drought tolerance, simulating optimal (OW) and restricted watering (RW) in a Mediterranean environment. Phenological, growth, and yield traits were recorded, and correlation analysis was performed. Accordingly, leaf temperature and osmotic potential were higher under RW, while the leaf chlorophyll content decreased in all landraces. Physiological maturity days and seed-filling days were lower in RW than in OW. This similarly occurred with the grain yield. The % yield reduction was negatively correlated with the % pod reduction and the relative rate of leaf expansion (RLAE) reduction. However, the 100-seed weight value was not significantly modified by water treatment (p > 0.05). For instance, landraces that preferred to fill the grain with a lower rate of leaf expansion showed a lower loss in grain yield under drought conditions. These results suggest that the resource partitioning between growing leaves, flowers, and developing pods in Chilean landraces is variable, affecting the common bean drought tolerance.

Phenolic Composition and α-Glucosidase Inhibition of Leaves from Chilean Bean Landraces.

The MeOH:H2O (7:3) extracts of leaves from Chilean bean landraces were assessed for total phenolic (TP), total flavonoid (TF), total proanthocyanidin (TPA) content, antioxidant capacity (ORAC, FRAP, TEAC, CUPRAC, DPPH) and the inhibition of enzymes associated with metabolic syndrome (α-glucosidase, α-amylase, pancreatic lipase). The chemical profiles were analyzed by HPLC-DAD. Higher antioxidant activity in the ORAC and CUPRAC assay was found for the landrace Coscorrón, and the best effect in the TEAC for Sapito, respectively. The main phenolics were flavonol glycosides and caffeic acid derivatives. The extracts presented strong activity against α-glucosidase, but were inactive towards α-amylase and pancreatic lipase. The leaf extract from the Sapito landrace was fractionated to isolate the main α-glucosidase inhibitors, leading to caffeoylmalic acid with an IC50 of 0.21 µg/mL. The HPLC fingerprints of the leaves differentiate three groups of chemical profiles, according to the main phenolic content. A significant correlation was found between the α-glucosidase inhibition, the content of caffeoylmalic acid (r = -0.979) and kaempferol 3-O-ß-D-glucoside (r = 0.942) in the extracts. The presence of α-glucosidase inhibitors in the leaves of Chilean beans support their potential as a source of bioactive compounds.

Screening South American Potato Landraces and Potato Wild Relatives for Novel Sources of Late Blight Resistance.

Late blight (LB) caused by the oomycete Phytophthora infestans is one of the most important biotic constraints for potato production worldwide. This study assessed 508 accessions (79 wild potato species and 429 landraces from a cultivated core collection) held at the International Potato Center genebank for resistance to LB. One P. infestans isolate belonging to the EC-1 lineage, which is currently the predominant type of P. infestans in Peru, Ecuador, and Colombia, was used in whole plant assays under greenhouse conditions. Novel sources of resistance to LB were found in accessions of Solanum albornozii, S. andreanum, S. lesteri, S. longiconicum, S. morelliforme, S. stenophyllidium, S. mochiquense, S. cajamarquense, and S. huancabambense. All of these species are endemic to South America and thus could provide novel sources of resistance for potato breeding programs. We found that the level of resistance to LB in wild species and potato landraces cannot be predicted from altitude and bioclimatic variables of the locations where the accessions were collected. The high percentage (73%) of potato landraces susceptible to LB in our study suggests the importance of implementing disease control measures, including planting susceptible genotypes in less humid areas and seasons or switching to genotypes identified as resistant. In addition, this study points out a high risk of genetic erosion in potato biodiversity at high altitudes of the Andes due to susceptibility to LB in the native landraces, which has been exacerbated by climatic change that favors the development of LB in those regions.[Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Mining Sources of Resistance to Durum Leaf Rust among Tetraploid Wheat Accessions from CIMMYT's Germplasm Bank.

A collection of 482 tetraploid wheat accessions from the CIMMYT Germplasm Bank was screened in the greenhouse for resistance to leaf rust disease caused by the fungus Puccinia triticina E. The accessions were screened against two races CBG/BP and BBG/BP in the field at two locations: against race CBG/BP at the Norman E. Borlaug Experimental Station (CENEB) located in the Yaqui Valley in the northern state of Sonora in Mexico during the 2014-2015 growing season; and against race BBG/BP at CIMMYT headquarters in El Batan, Texcoco, in the state of Mexico in the summer of 2015. Among the accessions, 79 durum genotypes were identified, of which 68 continued demonstrating their resistance in the field (past the seedling stage) against the two leaf rust races. An additional set of 41 genotypes was susceptible at the seedling stage, but adult plant race-specific resistance was identified in the field. The 79 seedling-resistant genotypes were tested against 15 different leaf rust races at the seedling stage to measure the usefulness of their resistance in a breeding program. Among the 79 accessions tested, 35 were resistant to all races used in the tests. Two sample sources, CIMMYT (18/35) pre-breeding germplasm and Ethiopian landraces (17/35), showed seedling resistance to all races tested except for seven landraces from Ethiopia, which became susceptible to the Cirno race identified in 2017.

Phenolic compounds and antioxidant activity in Cucurbita ficifolia fruits, an underrated fruit.

The fruits and seeds of Cucurbita ficifolia Bouché are sources of minerals, vitamins, and functional compounds with nutraceutical and preventive potential against cardiovascular diseases and diseases derived from eating disorders. C. ficifolia is native from Mesoamerica and is currently cultivated in temperate zones from Mexico to South America and Asia. This study evaluated the fruit mesocarps of C. ficifolia for physicochemical parameters, antioxidant activity, and phenolic compound contents in a collection of farmers' landraces. Germplasm is cultivated by traditional farmers in the temperate zones of two municipalities from Oaxaca, Mexico. The results show that the content of soluble solid contents (SSC), pH, total sugars (TS), and flavonoids are influenced by the fruit geographical origin (municipalities) and implicitly by their agroecological cultivation conditions (Huamelúlpam: SSC = 6.22 °Brix, pH = 5.44, TS = 0.52 mg G g-1, flavonoids = 1.24 mg CE g-1; Yanhuitlán: SSC = 6.69, pH = 5.33, TS = 0.55, flavonoids = 1.30). Among populations preserved by traditional farmers, significant differences, and wide variability were found for all parameters evaluated (Huamelúlpam: SSC = 4.9-7.3, pH = 5.5-5.8, TS = 0.4-0.7, protein = 5.8-11.4, polyphenols = 1.9-4.8, flavonoids = 1.0-1.5, DPPH = 4.3-10.6, and FRAP = 4.8-11.8; Yanhuitlán: SSC = 4.3-8.9, pH = 4.8-5.6, TS = 0.4-0.7, protein = 5.0-15.3, polyphenols = 1.9-4.9, flavonoids = 0.8-1.9, DPPH = 5.3-10.5, and FRAP = 4.5-12.6). Eight compounds were identified by UPLC-MS: L-phenylalanine, an amino acid that is regularly associated with proteins; vanillin, a phenolic aldehyde with its functional groups including aldehyde, hydroxyl, and ether; and six phenolic acids: 4-hydroxybenzoic acid, 4-hydroxyphenylacetic acid, vanillic acid, 4-coumaric acid, ferulic acid, and salicylic acid, all with potential health effects. The C. ficifolia fruit mesocarp has bioactive compounds with high antioxidant activity with the potential to both improve diet and to obtain other benefits against nontransmissible diseases derived from food and its associated risk factors.

Crop genetic erosion: understanding and responding to loss of crop diversity.

Crop diversity underpins the productivity, resilience and adaptive capacity of agriculture. Loss of this diversity, termed crop genetic erosion, is therefore concerning. While alarms regarding evident declines in crop diversity have been raised for over a century, the magnitude, trajectory, drivers and significance of these losses remain insufficiently understood. We outline the various definitions, measurements, scales and sources of information on crop genetic erosion. We then provide a synthesis of evidence regarding changes in the diversity of traditional crop landraces on farms, modern crop cultivars in agriculture, crop wild relatives in their natural habitats and crop genetic resources held in conservation repositories. This evidence indicates that marked losses, but also maintenance and increases in diversity, have occurred in all these contexts, the extent depending on species, taxonomic and geographic scale, and region, as well as analytical approach. We discuss steps needed to further advance knowledge around the agricultural and societal significance, as well as conservation implications, of crop genetic erosion. Finally, we propose actions to mitigate, stem and reverse further losses of crop diversity.