Landrace Groups Research Articles

Population Genetic Analysis of a Bread Wheat Panel from Northern and Huang-Huai Agro-Ecological Regions in China

Bread wheat (Triticum aestivum L.) is one of the most extensively cultivated cereal crops around the world. Here, we investigated the population structure and genetic diversity of a panel mainly originated from two wheat agro-ecological regions (northern winter wheat region, NW; and the Huang-Huai River Valley’s facultative wheat region, HH) in China based on a 15K SNP array. Population genetic analysis revealed that the optimal population number (K) was three, and the three groups were roughly related to ecological regions, including NW (mainly Hebei), HH1 (Henan-Shaanxi), and HH2 (Shandong). Within HH, HH1 had a higher nucleotide diversity (π = 0.31167), minor allele frequency (MAF = 0.2663), polymorphism information content (PIC = 0.2668), and expected heterozygosity (Hexp = 0.3346) than HH2. Furthermore, our results demonstrated that genetic diversity decreases with the advancement of wheat breeding. Finally, inference of ancestry informative markers indicated that the genomes of the three pure groups from the three provinces (Hebei, Henan, and Shandong) of the two regions have genomic regions with different mosaic patterns derived from the two landrace groups. These findings may facilitate the development of wheat breeding strategies to target novel desired alleles in the future.

Selective sweeps identification in distinct groups of cultivated rye (Secale cereale L.) germplasm provides potential candidate genes for crop improvement

BackgroundDuring domestication and subsequent improvement plants were subjected to intensive positive selection for desirable traits. Identification of selection targets is important with respect to the future targeted broadening of diversity in breeding programmes. Rye (Secale cereale L.) is a cereal that is closely related to wheat, and it is an important crop in Central, Eastern and Northern Europe. The aim of the study was (i) to identify diverse groups of rye accessions based on high-density, genome-wide analysis of genetic diversity within a set of 478 rye accessions, covering a full spectrum of diversity within the genus, from wild accessions to inbred lines used in hybrid breeding, and (ii) to identify selective sweeps in the established groups of cultivated rye germplasm and putative candidate genes targeted by selection.ResultsPopulation structure and genetic diversity analyses based on high-quality SNP (DArTseq) markers revealed the presence of three complexes in the Secale genus: S. sylvestre, S. strictum and S. cereale/vavilovii, a relatively narrow diversity of S. sylvestre, very high diversity of S. strictum, and signatures of strong positive selection in S. vavilovii. Within cultivated ryes we detected the presence of genetic clusters and the influence of improvement status on the clustering. Rye landraces represent a reservoir of variation for breeding, and especially a distinct group of landraces from Turkey should be of special interest as a source of untapped variation. Selective sweep detection in cultivated accessions identified 133 outlier positions within 13 sweep regions and 170 putative candidate genes related, among others, to response to various environmental stimuli (such as pathogens, drought, cold), plant fertility and reproduction (pollen sperm cell differentiation, pollen maturation, pollen tube growth), and plant growth and biomass production.ConclusionsOur study provides valuable information for efficient management of rye germplasm collections, which can help to ensure proper safeguarding of their genetic potential and provides numerous novel candidate genes targeted by selection in cultivated rye for further functional characterisation and allelic diversity studies.

The Origin of Spanish Durum Wheat and Olive Tree Landraces Based on Genetic Structure Analysis and Historical Records

In this study, the origin of Spanish durum wheat and olive tree landrace collections (preserved in seed banks and ex situ field collections, respectively) was traced throughout different studies on genetic structure analysis of different landrace collections and historical records of plant material circulation of these two crops in the south and east of Spain (the main cultivation areas). Although there were several groups of Spanish durum wheat landraces, they did not cluster geographically and likely came from intense grain circulation within the country and abroad (due to a high seeding rate of about 100 kg/ha and an unstable production) from the 15 to 19th centuries (especially the Maghreb and Sicily). However, Spanish olive tree landraces experienced lower genetic circulation over time and space due to the longevity of the species and the large size of the reproductive material. They can be clearly divided into two groups: those from the south, of Maghrebi origin, which most likely originated during the Islamic expansion of the 8–15th centuries, and those from the east, arriving most likely during Roman times from Italy. The genetic circularity levels of the plant material of these two crops are different.

Mitochondrial markers differentiate two distinct phylogenetic groups in indigenous rice landraces of northeast India: an evolutionary insight

The inheritance of the mitochondria genome and its diversity is unique for genetic and evolutionary studies relative to nuclear genomes. Northeast India and Himalayan regions are considered as one of the centres of indica rice origin. Also, rice diversity in northeast India is very distinct and highly suited for evolutionary studies. Although reports are available on the genetic diversity of indigenous northeast rice landraces, its relationship with the wild relatives is not yet properly explored and understood. In an attempt, mitochondrial markers were used to study the evolutionary relationship between the 68 landraces of northeast India and wild relatives (O. rufipogon and O. nivara) along with IR64 (indica) and Nipponbare (japonica) were taken as reference cultivars. Phylogenetically, the findings include two distinct clusters in the indigenous northeast India landraces representing indica and japonica groups. Further, the wild relatives and ~60% of northeast India landraces were identified to be closely related to the Nipponbare cluster. Besides, landraces of northeast India grouping with the indica group (IR64) are characterized by the absence of wild relatives. This indicates that there are two distinct evolutionary paths in the origin of northeast Indian rice landraces based on mitochondrial markers diversity and it is proposed that the inheritance of mitochondria, mitonuclear genome interactions, and bottleneck events could have genetically separated these two phylogenetically unique groups of northeast rice landraces.

On-farm diversity, use pattern, and conservation of enset (Ensete ventricosum) genetic resources in southern Ethiopia

BackgroundEnset is an important source of food and is consumed by about 25 million people as a staple or co-staple food crop mainly in southern parts of Ethiopia. Large numbers of enset landraces exist in different administrative zones of Ethiopia with a wide range of altitudes and agroclimatic zones. However, limited information is available on the diversity, distribution, and utilization pattern corresponding to the diverse ethnolinguistic as well as sociocultural communities of the country. Hence, this study was devised to explore and document the richness of farmers’ tradition and practice on the diversity and distribution of enset landraces on the farm level and selection pattern for different purposes regarding the production, utilization, and conservation of enset genetic resources.MethodsThe study was conducted in four major enset-growing administrative zones of Ethiopia, namely Hadiya, Kembata-Tembaro, Gurage, and Silte. A total of 240 farm households were surveyed using individual interviews, 18 key informant interviews, 36 focus group discussions with 5 participants, and direct on-farm field observations for data collection. Considering that enset has a rich cultural background and indigenous knowledge, ethnobotanical research approach was applied to data collection and analysis. The Shannon–Weaver, Simpson, Pielou, and Jaccard’s similarity indices were used to evaluate the diversity and similarity of the landraces as well as using descriptive statistics in SPSS Ver. 24. Preference in direct matrix ranking was also used to compute and rank the enset landraces most preferred by the people in the context of specific use value in the study area.ResultsA total of 282 farmer-named enset landraces have been identified, with a range from 2 to 32 on individual homegardens. The largest number of landraces was found in the Hadiya Zone (86), while the lowest was scored in the Silte Zone (57). The Shannon diversity index (H') ranged from 3.73 (Silte) to 3.96 (Hadiya). Similarly, landraces revealed a very narrow range of variances in Simpson’s 1-D diversity index, and it ranged from 0.963 (Silte) to 0.978 (Hadiya). Likewise, the similarity index ranged from 0.24 to 0.73 sharing 16–47 landraces in common. Of the 282 landraces, 210 (74.5%) were recorded in more than one zones, whereas 72 (25.5%) had narrow distribution being restricted to a single zone.ConclusionsFarmers have established long-term practices and experiences in cultivation, utilization, and conservation of a diverse group of enset landraces to fill their domestic and market purposes in each zone. The variation is likely to be related to agroclimatic differences, ethnicity factors, food cultures, and historical backgrounds. Therefore, to facilitate on-farm conservation as well as sustainable utilization of the enset genetic resources, farmers need to be supported by different stakeholders for all their worth and also in crop improvement programs.

Sweet Cherry Diversity and Relationships in Modern and Local Varieties Based on SNP Markers

The sweet cherry is an important fruit species that is widespread globally. In addition to the well-known traditional and modern varieties, a myriad of landraces is present in Europe, as well as in southern Italy. This study aims to evaluate the population structure, genetic relationships, and cases of duplicate samples in a collection of 143 accessions using GBS-derived SNP markers. The genetic material under investigation includes modern commercial varieties, ancient European and American varieties, landraces, and individuals retrieved from small orchards. Some of the known varieties were genetically analyzed here for the first time. In addition, several genotypes were collected from the Basilicata region (southern Italy), an area largely unexplored for sweet cherry genetic resources. The relationships among genotypes were assessed using four different methods: allele frequency and ancestry estimation, principal component analysis, Neighbor-Joining tree, and identity-by-state estimation. The analyses returned quite congruent results and highlighted the presence of four main genetic groups, namely: (i) American varieties, (ii) the 'Germersdorfer-Ferrovia' cluster, (iii) the 'Burlat' group, and (iv) the group of Italian landraces. The main drivers of clustering were ancestry, geographical distribution, and some important traits such as self-compatibility. The sweet cherries from Basilicata, herewith examined for the first time, were mostly distributed within the group of Italian landraces, being particularly linked to the autochthonous varieties of the Campania region. However, some genotypes were outside this group, thus suggesting the introduction of genetic material from other Italian regions or from European countries. The considerable amount of American and European modern varieties analyzed are genetically very closely related, suggesting a reduced genetic basis. In addition, we highlighted the discriminating ability of SNP markers to distinguish between an original variety and its mutant. Overall, our results may be useful in defining conservation strategies for sweet cherry germplasm and developing future breeding programs to enlarge the genetic basis of commercial varieties.

Comparative Genetic Analysis of Durum Wheat Landraces and Cultivars Widespread in Tunisia.

The durum wheat (Triticum turgidum L. ssp. durum Desf.) landraces constitute a useful natural germplasm to increase the genetic diversity in the modern durum cultivars. The Tunisian durum germplasm constitutes 28 accessions conserved in Genebank of Tunisia, which are still unexplored. In this study, a comparative genetic analysis was performed to investigate the relationships between the Tunisian durum lines and the modern cultivars and detect divergent loci involved in breeding history. The genetic diversity analyses carried out using nine morphological descriptors and the 25K single-nucleotide polymorphism (SNP) array allowed us to distinguish two groups of Tunisian landraces and one of durum cultivars. The analysis of molecular variance and diversity indices confirmed the genetic variability among the groups. A total of 529 SNP loci were divergent between Tunisian durum landraces and modern cultivars. Candidate genes related to plant and spike architecture, including FLOWERING LOCUS T (FT-B1), zinc finger CONSTANS, and AP2/EREBPs transcription factors, were identified. In addition, divergent genes involved in grain composition and biotic stress nucleotide-binding site and leucine-reach repeats proteins and disease resistance proteins (NBS-LRR and RPM) were found, suggesting that the Tunisian durum germplasm may represent an important source of favorable alleles to be used in future durum breeding programs for developing well-adapted and resilient cultivars.

State of ex situ conservation of landrace groups of 25 major crops

Crop landraces have unique local agroecological and societal functions and offer important genetic resources for plant breeding. Recognition of the value of landrace diversity and concern about its erosion on farms have led to sustained efforts to establish ex situ collections worldwide. The degree to which these efforts have succeeded in conserving landraces has not been comprehensively assessed. Here we modelled the potential distributions of eco-geographically distinguishable groups of landraces of 25 cereal, pulse and starchy root/tuber/fruit crops within their geographic regions of diversity. We then analysed the extent to which these landrace groups are represented in genebank collections, using geographic and ecological coverage metrics as a proxy for genetic diversity. We find that ex situ conservation of landrace groups is currently moderately comprehensive on average, with substantial variation among crops; a mean of 63% ± 12.6% of distributions is currently represented in genebanks. Breadfruit, bananas and plantains, lentils, common beans, chickpeas, barley and bread wheat landrace groups are among the most fully represented, whereas the largest conservation gaps persist for pearl millet, yams, finger millet, groundnut, potatoes and peas. Geographic regions prioritized for further collection of landrace groups for ex situ conservation include South Asia, the Mediterranean and West Asia, Mesoamerica, sub-Saharan Africa, the Andean mountains of South America and Central to East Asia. With further progress to fill these gaps, a high degree of representation of landrace group diversity in genebanks is feasible globally, thus fulfilling international targets for their ex situ conservation.

Traditional agricultural management of Kam Sweet Rice (Oryza sativa L.) in southeast Guizhou Province, China

BackgroundThe Dong people mainly live in Hunan, Guangxi and Guizhou provinces, China, with a long history of glutinous rice cultivation, among which Kam Sweet Rice (KSR) is a group of rice landraces that has been domesticated for thousands of years by the Dong people. The core distribution area of KSR is Liping, Congjiang and Rongjiang County of southeast, Guizhou Province. Paddy fields, forests, livestock and cottages have formed a special artificial wetland ecosystem in local area, and the Dong people have also formed a set of traditional farming systems of KSR for variety breeding, field management, and soil and water conservation. However, this traditional agricultural management has not been reported at multiple levels based on landraces, species and ecosystems.MethodsFieldwork was conducted in ten villages in southeast Guizhou from 2019 to 2021. A total of 229 informants were interviewed from the villages. Semi-structured and key informant interviews were administered to collect ethnoecological data on the characteristics and traditional utilization of KSR, traditional farming systems and agricultural management of the Dong people.Results(1): A total of 57 KSR landraces were recorded as used by the Dong people in southeast Guizhou. We analyzed the cultural importance index (CII) of all KSRs. KSR with high CII often has a pleasant taste, special biological characteristics of cold resistance, disease and insect resistance and high utilization in the traditional culture of Dong people. (2) There is a clear division of labor between men and women in the breeding, seed retention, field management and grain storage management of different landraces of KSR in Dong communities. In order to resist natural disasters and insect pests, the cultivation of KSR is usually managed by multi-variety mixed planting. These agricultural management modes are the result of Dong people’s understanding and adaptation to the local natural geographical environment, as well as the experience and wisdom crystallization of Dong people’s long-term practice. (3) The traditional farmland of Dong People is a typical artificial wetland ecosystem that is planted with mixed KSR landraces with rich traditional wisdom. In addition, the economic benefit of the rice–fish–duck symbiotic system was 3.07 times that of hybrid rice alone; therefore, the rice–fish–duck system not only has the function of maintaining soil, water and ecological balance but also improves the income of Dong people.ConclusionKSR is a special kind of rice that has been domesticated and cultivated by Dong people for thousands of years. Dong people have also formed traditional agriculture dominated by KSR cultivation. The traditional agricultural management of Dong people provides suitable habitats for flora and fauna with biodiversity protection, and convenient conditions for rational utilization and distribution of water resources were also provided. This traditional management mode is of great significance for environmental protection, climate change response, community resource management, sustainable utilization and agricultural transformation in modern society. Therefore, we call for interdisciplinary research in natural and social sciences, in-depth study of the ecological culture of ethnic areas, and sort out treasures conducive to the development of all mankind.

Genetic diversity analysis among different horticultural groups of indigenous and exotic Citrullus landraces using microsatellite markers

The study utilised a total of twenty simple sequence repeat (SSR) markers to investigate the genetic diversity of 53 watermelon accessions from different groups of Citrullus i.e., citroides, lanatus, and colocythis. Twelve of the twenty SSR markers were shown to be highly polymorphic and were statistically analyzed using Power Marker and NTSYSPc softwares. A total of 33 alleles were generated by polymorphic SSR markers, on an average of 2.6 alleles per loci. Heterozygosity among accessions for individual loci varied from zero to 0.17 (BVWS02306 marker).The gene diversity and PIC values varied between 0.08 to 0.72 and 0.46 to 0.90, respectively and the primer which had the highest gene diversity and PIC values was BVWS02422. The UPGMA-based dendrogram classified all the 53 accessions into two major clusters at 48 per cent similarity. All 41 cultivated watermelon accessions were grouped in cluster I and the remaining 12 accessions from wild types were grouped in cluster II. Thus, this study highlights the importance of molecular markers in the identification of wild and cultivated lines and their exploitation in future breeding programs. Keywords: Watermelon, genetic diversity, microsatellite, Jaccard similarity coefficient &nbsp

Phenotypic Diversity in Wild and Cultivated Date Palm (Phoenix, Arecaceae): Quantitative Analysis Using Information Theory

The quantitative study of genetic diversity requires tools to describe quantitatively and in parallel the whole phenotypic diversity in order to produce meaningful comparisons. The genus Phoenix offers examples of species with very different levels of diversity or heterogeneity. Within Phoenix, date palm (Phoenix dactylifera L.) is a major food crop of global relevance. The concept of information entropy was introduced by Claude Shannon; although initially intended to evaluate data communication systems, it has been used to measure biodiversity in terms of richness, evenness and dominance. In the present work, we will use it to describe heterogeneity within the different taxonomic units in the genus Phoenix. The description of the Phoenix morphological diversity in the present work is based on 596 accessions or populations belonging to 43 mutually exclusive taxonomic units (species, subspecies, varieties, landrace groups and hybrids). As Phoenix is a dioecious palm genus, female and male individuals are described separately. Each accession or sample is described using 116 characters totaling 449 states. The Shannon information entropy index allows the quantitative representation of the different levels of heterogeneity in the various taxonomic units of the genus Phoenix. Morphology, consistency and coloration of fruit and seed, followed by the inflorescences and female flowers, comprise the taxonomic characters that contribute the most to heterogeneity. Vegetative characters contribute less than the characters of the reproductive organs as a whole. Phoenix dactylifera and related Mediterranean and Macaronesian taxa present the maximum heterogeneity. Immediately afterwards we find P. loureiroi and, behind, the group of P. pusilla. At the lower limit of heterogeneity, we find species restricted in their distribution area: P. rupicola, P. theophrasti, P. roebelenii and P. acaulis. Phoenix dactylifera conforms to a complex of landraces and cultivars that coexist as phenotypically well-defined geographical groups with numerous intermediate forms and the long-distance translocation of otherwise local cultivars. This results in high heterogeneity. For the western and eastern groups of Phoenix dactylifera, it is extremely difficult to find a set of well-defined differential characters. However, some of the variables analyzed here allow us to propose a set of their respective syndromes. The high phenotypic heterogeneity in various Phoenix species is related to the genetic diversity, age and ancestry of different taxa, hybridization events and introgressions prior to domestication, and selective pressures after domestication and, again, interspecific crosses after domestication.

Turkish durum wheat conserved ex‐situ and in situ unveils a new hotspot of unexplored genetic diversity

AbstractDurum wheat (Triticum turgidum L.) is the 10th most cultivated crop and is a vital food source for human consumption. Genetic diversity in durum wheat is still an unexplored subject, and gene banks are filled with accessions waiting to be screened. Here, four different groups of durum wheat, Turkish and foreign cultivars, and in situ and ex situ landraces were evaluated for population structure and genetic diversity. A collection of 129 durum wheat accessions were genotyped, with a total of 6,357 markers (SilicoDArT, SNP [single‐nucleotide polymorphism], and simple sequence repeats [SSRs]). The highest mean allele number per marker (1.562) was obtained with SNP markers in ex situ landraces; the lowest mean allele number per marker (0.788) was obtained with SSR markers in the foreign cultivars. The minimum percentage of polymorphic loci was 38.70% observed with SSR markers in foreign cultivars; the maximum was 76.20% in SilicoDArT markers in ex situ landraces. According to Neighbor‐Joining analyses, the studied collection was divided into groups of cultivars and landraces, with some level of admixtures. Structure and principal coordinate analysis obtained distinct clusters for ex situ landraces and foreign cultivars, supported by Neighbor‐Joining analysis. A significant level of intergroup and intragroup variation was observed, and Turkish ex situ landraces were found as the most diverse and distinct group in the collection. Turkish landraces may be a promising source of novel allelic diversity that can be used in durum wheat breeding worldwide.

The Genetic Diversity of Enset (Ensete ventricosum) Landraces Used in Traditional Medicine Is Similar to the Diversity Found in Non-medicinal Landraces.

Enset (Ensete ventricosum) is a multipurpose crop extensively cultivated in southern and southwestern Ethiopia for human food, animal feed, and fiber. It has immense contributions to the food security and rural livelihoods of 20 million people. Several distinct enset landraces are cultivated for their uses in traditional medicine. These landraces are vulnerable to various human-related activities and environmental constraints. The genetic diversity among the landraces is not verified to plan conservation strategy. Moreover, it is currently unknown whether medicinal landraces are genetically differentiated from other landraces. Here, we characterize the genetic diversity of medicinal enset landraces to support effective conservation and utilization of their diversity. We evaluated the genetic diversity of 51 enset landraces, of which 38 have reported medicinal value. A total of 38 alleles across the 15 simple sequence repeat (SSR) loci and a moderate level of genetic diversity (He = 0.47) were detected. Analysis of molecular variation (AMOVA) revealed that only 2.4% of the total genetic variation was contributed by variation among the medicinal and non-medicinal groups of landraces, with an FST of 0.024. A neighbor-joining tree showed four separate clusters with no correlation to the use-values of the landraces. Except for two, all “medicinal” landraces with distinct vernacular names were found to be genetically different, showing that vernacular names are a good indicator of genetic distinctiveness in these specific groups of landraces. The discriminant analysis of the principal components also confirmed the absence of distinct clustering between the two groups. We found that enset landraces were clustered irrespective of their use-value, showing no evidence for genetic differentiation between the enset grown for ‘medicinal’ uses and non-medicinal landraces. This suggests that enset medicinal properties may be restricted to a more limited number of genotypes, might have resulted from the interaction of genotype with the environment or management practice, or partly misreported. The study provides baseline information that promotes further investigations in exploiting the medicinal value of these specific landraces.

Genetic and Morpho-Agronomic Characterization of Sicilian Tetraploid Wheat Germplasm.

Cereal landraces are a very valuable resource in contemporary agriculture. A renewed focus for breeding purposes could ameliorate some negative consequences of modern agriculture and conventional breeding, such as the loss of genetic diversity. One strategy combining molecular genotyping and characterization of morpho-agronomic traits related to productivity is proposed to assess a group of tetraploid wheat landraces named Bufala, historically cultivated in the mountain areas of Sicily and characterized by adaptability in terms of cold tolerance, ability to grow in marginal soils, weed competitiveness and resistance to diseases. A total of 55 SSR molecular markers were used to detect patterns of diversity in 30 rivet and durum wheat genotypes. Furthermore, phenotyping was then conducted for 8 morpho-agronomic traits. Discriminant analysis of principal components (DAPC), STRUCTURE and phylogenetical analysis allowed to identify three groups, two of them genetically close and including both Bufala and Bufala-related rivet landraces. To the third group, old and more recent durum wheat varieties, constituting the outgroup, were assigned. Clustering was confirmed by Principal Component Analysis (PCA). Finally, a correlation analysis showed that Bufala genotypes are characterized by lower ear density, major ear length and later earing time compared with the other studied genotypes. The levels of diversity and population structure could be an important contribution to parent selection in tetraploid wheat breeding programs, as well as to germplasm conservation and management.

Diversity and Adaptation of Currently Grown Wheat Landraces and Modern Germplasm in Afghanistan, Iran, and Turkey

Collection of wheat landraces (WLR) was conducted in Afghanistan, Iran, and Turkey in 2010–2014. A representative subset of this collection was used in the current study and included 45 bread wheat landraces from Turkey, 19 from Iran, and 20 from Afghanistan. This material was supplemented by 73 modern cultivars and breeding lines adapted to semiarid conditions and irrigated conditions. Overall, 157 genotypes were tested in Turkey in 2018 and 2019 and in Afghanistan and Iran in 2019 under rainfed conditions to compare performance of WLR and modern material. The germplasm was genotyped using a high density Illumina Infinium 25K wheat SNP array and KASP markers for agronomic traits. The average grain yield ranged between 2.2 and 4.0 t/ha depending on the site and year. Three groups of landraces demonstrated similar average grain yield, though Afghanistan material was slightly higher yielding not only in Afghanistan but also in Turkey. Modern material outyielded the landraces in two environments out of four. The highest yielding landraces were competitive with the best modern germplasm. Frequency of gene Sus2-2B affecting 1000 kernel weight was 64% in WLR and only 3% in modern material. Presence of positive allele of Sus2-2B increased 1000 kernel weight by nearly 4%. Breeding strategy to improved landraces and modern cultivars is discussed.

Phenotypic diversity and capsaicinoid content of chilli pepper landraces (Capsicum spp.) from the Yucatan Peninsula

AbstractMexico has a wealth of plant genetic resources, including Capsicum species. In southern Mexico, specifically in the western part of the Yucatan Peninsula, Maya farmers have preserved a great diversity of chilli pepper landraces of C. annuum, C. frutescens and C. chinense. However, the morphological diversity, capsaicinoid content, conservation status and potential use of these species have not been studied. To fill this gap and generate information to support the conservation and use of these species, we characterized the phenotypic diversity and capsaicinoid content for nine chilli pepper landraces from the western Yucatan Peninsula by assessing 15 quantitative and 39 qualitative traits for 10 plants of each landrace. For quantitative variables, two groups of chilli pepper landraces were obtained by principal component analysis and cluster analysis. Group I was formed by Rosita, Bobo, Dulce, Xcat'ik1, Xcat'ik2 and Verde landraces; Group II included the Maax, Bolita and Pico Paloma landraces. For qualitative variables, three groups of chilli pepper landraces were obtained; Group I included Dulce, Bobo, Xcat'ik1, Xcat'ik2 and Verde landraces, Group II only included the Rosita landrace, and Group III included Maax, Bolita and Pico Paloma landraces. Ultra-performance liquid chromatography–photodiode array (UPLC-PDA) quantification of capsaicinoids indicated higher values in landraces Rosita (14,062.3 μg/g D.W), Bolita (5928.1 μg/g D.W), Maax (3438.4 μg/g D.W) and Pico Paloma (3138.9 μg/g D.W). The Yucatan chilli pepper landraces provide valuable diverse germplasm for morphological characteristics and capsaicinoid content that can be used in breeding and conservation programmes.

Diversity of Leaf Cuticular Transpiration and Growth Traits in Field-Grown Wheat and Aegilops Genetic Resources

Plants are subjected to unregulated water loss from their surface by cuticular transpiration. Therefore, specific morphophysiological changes may occur during leaf development to eliminate water loss. This study aimed to examine the cuticular transpiration of 23 winter wheat genotypes and their wild-growing predecessors of the genus Aegilops, which were divided into three groups to demonstrate their diversity. The genotypes were sown in autumn and grown in regular field trials at the Research Institute of Plant Production in Piešťany, Slovakia. Cuticular transpiration and growth parameters were analyzed in the postanthesis growth stage. Gravimetric measurement of residual water loss was performed on detached leaves with a precisely measured leaf area. The lowest nonproductive transpiration values were observed in modern wheat genotypes, while higher cuticular transpiration was observed in a group of landraces. Aegilops species generally showed the highest cuticular transpiration with increased water loss, but the total water loss per plot was low due to the low leaf area of the wild wheat relatives. Some of the growth parameters showed a good correlation with cuticular transpiration (e.g., dry mass per plant), but direct relationships between leaf traits and cuticular transpiration were not observed. This study identified a high diversity in cuticular resistance to water loss in wheat and Aegilops accessions of different origins. The potential of identifying and exploiting genetic resources with favorable cuticular transpiration in crop breeding is discussed.

Plastome genomics in South American maize landraces: chloroplast lineages parallel the geographical structuring of nuclear gene pools.

The number of plastome sequences has increased exponentially during the last decade. However, there is still little knowledge of the levels and distribution of intraspecific variation. The aims of this study were to estimate plastome diversity within Zea mays and analyse the distribution of haplotypes in connection with the landrace groups previously delimited for South American maize based on nuclear markers. We obtained the complete plastomes of 30 South American maize landraces and three teosintes by means of next-generation sequencing (NGS) and used them in combination with data from public repositories. After quality filtering, the curated data were employed to search for single-nucleotide polymorphisms, indels and chloroplast simple sequence repeats. Exact permutational contingency tests were performed to assess associations between plastome and nuclear variation. Network and Bayesian phylogenetic analyses were used to infer evolutionary relationships among haplotypes. Our analyses identified a total of 124 polymorphic plastome loci, with the intergenic regions psbE-rps18, petN-rpoB, trnL_UAG-ndhF and rpoC2-atpI exhibiting the highest marker densities. Although restricted in number, these markers allowed the discrimination of 27 haplotypes in a total of 51 Zea mays individuals. Andean and lowland South American landraces differed significantly in haplotype distribution. However, overall differentiation patterns were not informative with respect to subspecies diversification, as evidenced by the scattered distribution of maize and teosinte plastomes in both the network and Bayesian phylogenetic reconstructions. Knowledge of intraspecific plastome variation provides the framework for a more comprehensive understanding of evolutionary processes at low taxonomic levels and may become increasingly important for future plant barcoding efforts. Whole-plastome sequencing provided useful variability to contribute to maize phylogeographic studies. The structuring of haplotype diversity in the maize landraces examined here clearly reflects the distinction between the Andean and South American lowland gene pools previously inferred based on nuclear markers.

Distribution of two groups of melon landraces and inter-group hybridization enhanced genetic diversity in Vietnam.

To understand the genetic diversity and differentiation of Vietnamese melon (Cucumis melo L.), we collected 64 landraces from the central and southern parts of the country and assessed molecular polymorphism using simple sequence repeat and random amplified polymorphic DNA markers. The Vietnamese melon was divided into seven cultivar groups, namely “Dua le”, “Dua vang”, “Dua bo”, “Dua gang-andromonoecious”, “Dua gang-monoecious”, “Dua thom”, “Montok”, and the weedy-type melon “Dua dai”. Among these, Dua le, Dua vang, Dua bo, and Dua gang-andromonoecious are cultivated on plains and they formed cluster II along with the reference accessions of Conomon and Makuwa. Based on genetic distance, Dua le and Dua vang were regarded as Makuwa and Dua bo and Dua gang-andromonoecious as Conomon. In contrast, Dua thom and Montok are cultivated in highlands, and they formed cluster III along with landraces from the southern and eastern foot of the Himalayas. Dua gang-monoecious which is commonly cultivated in the southern parts of Vietnam, exhibited the greatest genetic diversity, as explained by its possible origin through the hybridization between Dua gang-andromonoecious and Montok. Genetic differences in melon landraces between plains and highlands and hybridization between these two geographical groups have contributed to the enhancement of genetic diversity in Vietnamese melon.

The genetic diversity of group-1 homoeologs and characterization of novel LMW-GS genes from Chinese Xinjiang winter wheat landraces (Triticum aestivum L.).

Group-1 homoelog genes in wheat genomes encode storage proteins and are the major determinants of wheat product properties. Consequently, understanding the genetic diversity of group-1 homoelogs and genes encoding storage proteins, especially the low-molecular-weight glutenins (LMW-GSs), within wheat landrace genomes is necessary to further improve the quality of modern wheat crops. The genetic diversity of group-1 homoelogs in 75 Xinjiang winter wheat landraces was evaluated by Diversity Arrays Technology (DArT) markers. These data were used to select 15 landraces for additional LMW-GS gene isolation. The genetic similarity coefficients among landraces were highly similar regardless if considering the diversity markers on 1A, 1B, and 1D chromosomes individually or using all of the markers together. These similarities were evinced by the generation of four similar cluster dendrograms that comprised 11-15 landrace groups, regardless of the dataset used to generate the dendrograms. A total of 105 LMW-GS sequences corresponding to 79 unique genes were identified overall by using primers designed to target Glu-A3 and Glu-B3 loci, and 54 mature proteins were predicted from the unique LMW-GS genes. Nine novel chimeric LMW-GS genes were also identified, of which, one was recombinant for -i/-m, one for -s/-m, and seven for -m/-m parent genes, respectively. Phylogenetic analysis separated all of the LMW-GSs into three clades that were supported by moderate bootstrap values (> 70%). The clades corresponded to LMW-GS genes primarily harboring different N-terminals. These results provide useful information for better understanding the evolutionary genetics of the important Glu-3 locus of wheat, and they also provide new novel gene targets that can potentially be exploited to improve wheat quality.