Defining and identifying crop landraces

2005 ◽  
Vol 3 (3) ◽  
pp. 373-384 ◽  
Author(s):  
Tania Carolina Camacho Villa ◽  
Nigel Maxted ◽  
Maria Scholten ◽  
Brian Ford-Lloyd
Keyword(s):  
Genetic Diversity ◽  
Crop Improvement ◽  
Farming Systems ◽  
Traditional Farming ◽  
Crop Species ◽  
High Genetic Diversity ◽  
Working Definition ◽  
Landrace Diversity ◽  
Cultivated Plant ◽  
Historical Origin

Awareness of the need for biodiversity conservation is now universally accepted, but most often recent conservation activities have focused on wild species. Crop species and the diversity between and within them has significant socioeconomic as well as heritage value. The bulk of genetic diversity in domesticated species is located in traditional varieties maintained by traditional farming systems. These traditional varieties, commonly referred to as landraces, are severely threatened by genetic extinction primarily due to their replacement by modern genetically uniform varieties. The conservation of landrace diversity has been hindered in part by the lack of an accepted definition to define the entity universally recognized as landraces. Without a definition it would be impossible to prepare an inventory and without an inventory changes in landrace constituency could not be recognized over time. Therefore, based on a literature review, workshop discussion and interviews with key informants, common characteristics of landraces were identified, such as: historical origin, high genetic diversity, local genetic adaptation, recognizable identity, lack of formal genetic improvement, and whether associated with traditional farming systems. However, although these characteristics are commonly present they are not always all present for any individual landrace; several crop-specific exceptions were noted relating to crop propagation method (sexual or asexual), breeding system (self-fertilized or cross-fertilized species), length of formal crop improvement, seed management (selection or random propagation) and use. This paper discusses the characteristics that generally constitute a landrace, reviews the exceptions to these characteristics and provides a working definition of a landrace. The working definition proposed is as follows: ‘a landrace is a dynamic population(s) of a cultivated plant that has historical origin, distinct identity and lacks formal crop improvement, as well as often being genetically diverse, locally adapted and associated with traditional farming systems’.

scholarly journals Social and environmental factors in the diversity of tomato landraces from the South-Central region of Mexico

2019 ◽  
Vol 49 (5) ◽  
Author(s):  
Yolanda del Rocio Moreno-Ramírez ◽  
Aurelio Hernández-Bautista ◽  
Porfirio Ramírez-Vallejo ◽  
Fernando Castillo-Gónzalez ◽  
Mario Rocandio-Rodríguez ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Environmental Factors ◽  
Central Region ◽  
Selection Criteria ◽  
Farming Systems ◽  
The South ◽  
Traditional Farming ◽  
South Central ◽  
Morphological Differences ◽  
Ethnolinguistic Group

ABSTRACT: In the present study, we investigated the influence of social and environmental factors in the genetic diversity of tomato landraces in the South-Central region of Mexico. A total of 30 tomato landraces, collected in 18 villages with different ethnolinguistic affiliations, were analyzed. We reported that the genetic diversity of tomato landraces is associated with the ethnolinguistic group, weather, and soil-type present in the region studied. Our results showed that there are morphological differences between landraces grown by different ethnolinguistic groups; however, there was also evidence of morphological similarities between landraces from groups with different ethnolinguistic affiliations. Finally, different selection criteria, mainly fruit color, size and shape, plays an important role in the phenotypic divergence among landraces grown in different traditional farming systems.

scholarly journals Assessment of Genetic Diversity among Indian and Exotic Genotypes of Brassica juncea using Phenotypic Evaluation

2020 ◽  
Author(s):  
Vivek K. Singh ◽  
Ram Avtar ◽  
Mahavir . ◽  
Nisha Kumari ◽  
Manjeet . ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Brassica Juncea ◽  
Crop Improvement ◽  
Morphological Characters ◽  
Germplasm Management ◽  
Dissimilarity Matrix ◽  
High Genetic Diversity ◽  
Early Maturity ◽  
Mean Values ◽  
Dissimilarity Coefficients

Background: Rapeseed-mustard is one of the most important oilseed crops in India, however, its genetic diversity is barely known. A better understanding on this topic is essential for the proper utilization of genotypes in crop improvement. Methods: Present study was carried out to determine the genetic diversity among 95 diverse genotypes of Brassica juncea (L.) in paired rows of 4 m length with a spacing of 30 x 10-15 cm (row × plant). Data were recorded on 11 different agro-morphological characters. Result: All the 95 genotypes were grouped into five distinct clusters based on Manhattan dissimilarity coefficients. Amongst the five clusters, cluster V and IV had the maximum number of genotypes (35 and 23 genotypes respectively) and cluster II with least number of genotypes (three). The Manhattan dissimilarity coefficients ranged from 0.741 to 8.299. Based on the genetic dissimilarity matrix, the maximum dissimilarity (8.299) was observed between the genotypes, DRMRIJ-15-133 and M 62. Cluster III recorded for medium plant height with medium early maturity and cluster I, had maximum mean values for most of the agro-morphological traits. The present work indicated the presence of high genetic diversity among genotypes, which can be used in future breeding programmes for developing mustard cultivars and germplasm management purposes.

scholarly journals Assessment of Genetic Diversity and Marker-Trait Associations Using Selected Early Maize Inbreds Derived From Local Landraces of Eastern Himalayan Regions

2021 ◽  
Author(s):  
E. Lamalakshmi Devi ◽  
Umakanta Ngangkham ◽  
Akoijam Ratankumar Singh ◽  
Bhuvaneswari S ◽  
Konsam Sarika ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Agronomic Traits ◽  
Crop Improvement ◽  
Mean Value ◽  
Cross Combination ◽  
High Genetic Diversity ◽  
Average Value ◽  
Maize Inbreds ◽  
High Level ◽  
Trait Associations

Abstract North- Eastern parts of India fall under Eastern Himalayan region and it is a diversity hotspot of many crops including maize. Evaluation of genetic diversity is required to tape the potentiality of genetic resources in any crop improvement programmes. In the present study, genetic diversity at fifty two microsatellite markers were conducted in 30 early maize inbreds developed from local landraces of NE India. Genetic diversity analysis revealed a total of 189 alleles with a mean of 3.63 alleles/ locus. The allele size ranged from 50 bp (phi 036) to 295 bp (p 101049) which revealed a high level of genetic diversity among the loci. The PIC among the 30 genotypes ranged from 0.17 (umc 1622) to 0.76 (umc 1153) with an average value of 0.49. The value of Expected Heterozygosity (HExp) ranged from 0.19 to 0.80 with an average of 0.57, whereas the Observed Heterozygosity (HObs) ranged from 0 to 0.89 with a mean of 0.14.The genetic dissimilarity between the genotype pairs ranged from 0.40 to 0.64 with a mean value of 0.57. Cluster analysis grouped the 30 inbreds into distinct three sub-clusters. Similarly, population structure and principal coordinate analysis) analysis also classified the 30 inbred lines into three-subpopulations. AMOVA revealed that 6% of total variance is due to differences among populations, while 94% of total molecular variance is accounted by within populations. Marker-trait associations showed a total of twelve SSR markers significantly associated with seven agronomic traits. From the present finding, these results show that the thirty maize inbreds have high genetic diversity which would be useful for choosing promising parents and for making cross combination based on genetic distance and clustering for genetic improvement programmes of maize.

scholarly journals Molecular diversity analysis of genotypes from four Aegilops species based on retrotransposon–microsatellite amplified polymorphism (REMAP) markers

2020 ◽  
Author(s):  
Justyna Leśniowska-Nowak ◽  
Sylwia Okoń ◽  
Aleksandra Wieremczuk
Keyword(s):  
Genetic Diversity ◽  
Molecular Diversity ◽  
Crop Improvement ◽  
Diversity Analysis ◽  
Aegilops Species ◽  
Powerful Method ◽  
High Genetic Diversity ◽  
Breeding Programs ◽  
Genetic Diversity Analysis ◽  
Valuable Source

Abstract Genetic diversity analysis is an important tool in crop improvement. Species with high genetic diversity are a valuable source of variation used in breeding programs. The aim of this study was to assess the genetic diversity of four species belonging to the genus Aegilops, which are often used to expand the genetic variability of wheat and triticale. Forty-five genotypes belonging to the genus Aegilops were investigated. Within- and among-species genetic diversity was calculated based on REMAP (retrotransposon–microsatellite amplified polymorphism) molecular markers. Obtained results showed that REMAP markers are a powerful method for genetic diversity analysis, which produces a high number of polymorphic bands (96.09% of total bands were polymorphic). Among tested genotypes, Ae. crassa and Ae. vavilovii showed the highest genetic diversity and should be chosen as a valuable source of genetic variation.

scholarly journals A global barley panel revealing genomic signatures of breeding in modern cultivars

2020 ◽  
Author(s):  
Camilla Beate Hill ◽  
Tefera Tolera Angessa ◽  
Xiao-Qi Zhang ◽  
Kefei Chen ◽  
Gaofeng Zhou ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Agronomic Traits ◽  
Crop Improvement ◽  
Genetic Erosion ◽  
Germplasm Collection ◽  
Geographic Region ◽  
Climatic Conditions ◽  
Crop Species ◽  
Diverse Range ◽  
The Impact

AbstractThe future of plant cultivar improvement lies in the evaluation of genetic resources from currently available germplasm. Recent efforts in plant breeding have been aimed at developing new and improved varieties from poorly adapted crops to suit local environments. However, the impact of these breeding efforts is poorly understood. Here, we assess the contributions of both historical and recent breeding efforts to local adaptation and crop improvement in a global barley panel by analysing the distribution of genetic variants with respect to geographic region or historical breeding category. By tracing the impact breeding had on the genetic diversity of barley released in Australia, where the history of barley production is relatively young, we identify 69 candidate regions within 922 genes that were under selection pressure. We also show that modern Australian barley varieties exhibit 12% higher genetic diversity than historical cultivars. Finally, field-trialling and phenotyping for agriculturally relevant traits across a diverse range of Australian environments suggests that genomic regions under strong breeding selection and their candidate genes are closely associated with key agronomic traits. In conclusion, our combined dataset and germplasm collection provide a rich source of genetic diversity that can be applied to understanding and improving environmental adaptation and enhanced yields.Author summaryToday’s gene pool of crop genetic diversity has been shaped during domestication and more recently by breeding. Genetic diversity is vital for crop species to be able to adapt to changing environments. There is concern that recent breeding efforts have eroded the genetic diversity of many domesticated crops including barley. The present study assembled a global panel of barley genotypes with a focus on historical and modern Australian varieties.Genome-wide data was used to detect genes that are thought to have been under selection during crop breeding in Australian barley. The results demonstrate that despite being more extensively bred, modern Australian barley varieties exhibit higher genetic diversity than historical cultivars, countering the common perception that intensive breeding leads to genetic erosion of adaptive diversity in modern cultivars. In addition, some loci (particularly those related to phenology) were subject to selection during the introduction of other barley varieties to Australia – these genes might continue to be important targets in breeding efforts in the face of changing climatic conditions.

Breeding for cuticle-associated traits in crop species: traits, targets, and strategies

2017 ◽  
Vol 68 (19) ◽  
pp. 5369-5387 ◽  
Author(s):  
Johann Petit ◽  
Cécile Bres ◽  
Jean-Philippe Mauxion ◽  
Bénédicte Bakan ◽  
Christophe Rothan
Keyword(s):  
Genetic Diversity ◽  
Genetic Resources ◽  
Water Loss ◽  
Crop Improvement ◽  
Species Traits ◽  
Crop Productivity ◽  
Crop Breeding ◽  
Crop Species ◽  
Horticultural Crops ◽  
Cuticle Formation

Abstract Improving crop productivity and quality while promoting sustainable agriculture have become major goals in plant breeding. The cuticle is a natural film covering the aerial organs of plants and consists of lipid polyesters covered and embedded with wax. The cuticle protects plants against water loss and pathogens and affects traits with strong impacts on crop quality such as, for horticultural crops, fruit brightness, cracking, russeting, netting, and shelf life. Here we provide an overview of the most important cuticle-associated traits that can be targeted for crop improvement. To date, most studies on cuticle-associated traits aimed at crop breeding have been done on fleshy fruits. Less information is available for staple crops such as rice, wheat or maize. Here we present new insights into cuticle formation and properties resulting from the study of genetic resources available for the various crop species. Our review also covers the current strategies and tools aimed at exploiting available natural and artificially induced genetic diversity and the technologies used to transfer the beneficial alleles affecting cuticle-associated traits to commercial varieties.

Methodology to establish a composite collection: case study in lentil

2006 ◽  
Vol 4 (1) ◽  
pp. 2-12 ◽  
Author(s):  
Bonnie J Furman
Keyword(s):  
Genetic Diversity ◽  
Large Scale ◽  
Dna Analysis ◽  
Agronomic Traits ◽  
Agricultural Research ◽  
Crop Improvement ◽  
Hierarchical Cluster ◽  
Wild Relatives ◽  
Crop Species ◽  
Cluster Analyses

The International Center for Agricultural Research in the Dry Areas (ICARDA) is participating in a large-scale programme, Subprogram 1 of the Consultative Group on International Agricultural Research (CGIAR) Generation Challenge Program, that aims to explore the genetic diversity of the global germplasm collections held by the CGIAR research centres. This project will identify a ‘composite collection’ of germplasm for individual crops, representing the range of diversity of each crop species and its wild relatives, and characterize each composite set using anonymous molecular markers, mainly simple sequence repeats (SSRs). The overall goal of this project is to study diversity across given genera and identify genes for resistance to biotic and abiotic stresses that can be used in crop improvement programmes. ICARDA was responsible for creating the composite collection for lentil. ICARDA has the global mandate for lentil and houses the largest global collection of this crop with 10,509 accessions. From this collection, a global composite collection of 1000 lentil accessions was established with the aim to represent genetic diversity and the agro-climatological range of lentil. Accessions for the composite collection were compiled from landraces, wild relatives, and elite germplasm and cultivars. The methodology presented here combined classical hierarchical cluster analyses using agronomic traits and two-step cluster analyses using agro-climatological data linked to the geographical coordinates of the accessions' collection sites. Genotyping for 30 SSR loci will be carried out for all 1000 accessions. Plants grown for DNA analysis will be harvested and progeny will be evaluated under field conditions at ICARDA.

scholarly journals Combining ability and heterosis in plant improvement

2021 ◽  
pp. 108-117
Author(s):  
Begna Temesgen
Keyword(s):  
Genetic Diversity ◽  
Combining Ability ◽  
Crop Improvement ◽  
Critical Factor ◽  
Hybrid Vigor ◽  
Hybrid Breeding ◽  
F1 Hybrids ◽  
Gene Pools ◽  
Crop Species ◽  
Heterotic Groups

Information on combining ability and heterosis of parents and crossings is crucial in breeding efforts. Genetic variety is crucial to the effectiveness of yield improvement efforts because it helps to broaden gene pools in any given crop population. The genotype's ability to pass the intended character to the offspring is referred to as combining ability. As a result, information on combining ability is required to determine the crossing pairs in the production of hybrid varieties. Heterosis is the expression of an F1 hybrid's dominance over its parents in a given feature, as measured not by the trait's absolute value, but by its practical use. To put it another way, heterosis is defined as an increase in the character value of F1 hybrids when compared to the average value of both parents. A plant breeder's ultimate goal is to achieve desirable heterosis (hybrid vigor). In a variety of crop species, heterosis has been widely employed to boost output and extend the adaptability of hybrid types. A crucial requirement for discovering crosses with significant levels of exploitable heterosis is knowledge of the quantity of heterosis in different cross combinations. Any crop improvement program's success is contingent on the presence of a significant level of genetic diversity and heritability. The lack of a broad genetic foundation is the most significant constraint to crop improvement and a major bottleneck in breeding operations. Heterosis is a critical factor in hybrid generation, particularly for traits driven by non-additive gene activity. To get the most out of heterosis for hybrid cultivar production, germplasm must be divided into distinct heterotic groups. Similarly, knowledge on genetic diversity is critical for hybrid breeding and population improvement initiatives because it allows them to analyze genetic diversity, characterize germplasm, and categorize it into different heterotic groupings. In general, general combining ability is used to detect a line's average performance in a hybrid combination, whereas specific combining ability is used to find circumstances where definite combinations perform better or worse than expected based on the mean performance of the lines involved.

scholarly journals A Genomics Resource for Genetics, Physiology, and Breeding of West African Sorghum

2020 ◽  
Author(s):  
Jacques M. Faye ◽  
Fanna Maina ◽  
Eyanawa A. Akata ◽  
Bassirou Sine ◽  
Cyril Diatta ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
West Africa ◽  
Association Studies ◽  
Crop Improvement ◽  
West African ◽  
Gene Pools ◽  
Genome Wide Association Studies ◽  
High Genetic Diversity ◽  
Canonical Height ◽  
Genome Wide

AbstractLocal landrace and breeding germplasm is a useful source of genetic diversity for regional and global crop improvement initiatives. Sorghum (Sorghum bicolor L. Moench) in West Africa has diversified across a mosaic of cultures and end-uses, and along steep precipitation and photoperiod gradients. To facilitate germplasm utilization, a West African sorghum association panel (WASAP) of 756 accessions from national breeding programs of Niger, Mali, Senegal, and Togo was assembled and characterized. Genotyping-by-sequencing was used to generate 159,101 high-quality biallelic SNPs, with 43% in intergenic regions and 13% in genic regions. High genetic diversity was observed within the WASAP (π = 0.00045), only slightly less than in a global diversity panel (π = 0.00055). Linkage disequilibrium decayed to background level (r2 < 0.1) by ~50 kb in the WASAP. Genome-wide diversity was structured both by botanical type, and by populations within botanical type, with eight ancestral populations identified. Most populations were distributed across multiple countries, suggesting several potential common gene pools across the national programs. Genome-wide association studies of days to flowering and plant height revealed eight and three significant quantitative trait loci (QTL), respectively, with major height QTL at canonical height loci Dw3 and SbHT7.1. Colocalization of two of eight major flowering time QTL with flowering genes previously described in US germplasm (Ma6 and SbCN8) suggests that photoperiodic flowering in WA sorghum is conditioned by both known and novel genes. This genomic resource provides a foundation for genomics-enabled breeding of climate-resilient varieties in West Africa.

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