Assessment of Agro-Morphological Variability in a Durum Wheat Collection Maintained in the Moroccan Gene Bank

Durum wheat is one of the most important cereal crops in Morocco. The development of high-yielding varieties of durum wheat is one of the major goals of breeding programs in Morocco. Crop genetic diversity should play an essential role in this context. The objective of this study was to assess the genetic variation among 280 durum wheat accessions conserved at the Moroccan Gene Bank by using twelve agro-morphological characters. All accessions are planted in field conditions and arranged in augmented design. The results showed a large variability among the durum wheat accessions. Analysis of variance demonstrated significant to highly significant differentiation between the accessions for the most traits. The number of plants at the emergence stage, the biomass of the plant at the flowering stage, the chlorophyll content, and the number of spikes showed high genetic advance coupled with high heritability (broad sense). Moreover, highly significant coefficients of correlation were revealed between agro-morphological characters offering the possibility of direct or indirect selection. The first two axes of the principal component analysis explained 45% of the total variation and showed that Moroccan landraces and North American cultivars shared similar morphological characters. However, Moroccan cultivars have shown better agronomic characters. This important agro-morphological variation should be utilized as a gene pool in durum wheat improvement to develop novel varieties with high productivity and the best quality.

Varietal Threat Index for Monitoring Crop Diversity on Farms in Five Agro-Ecological Regions in India

Our knowledge about the status of agrobiodiversity on farms is still very limited. While several studies to assess the crop genetic diversity on farms have been undertaken, there are no systematic documentation and monitoring practices for varietal diversity in space and time. Achievement of the agrobiodiversity Aichi Target 13, established under the Biodiversity Strategy Plan 2011–2020, have failed due to the lack of existing data on varietal diversity at country, regional and global levels. Here, we propose a method for calculating the Varietal Threat Index using the four-cell analysis (FCA) participatory methodology at different geographical scales to monitor changes in the varietal diversity on farms and to compare between areas. We tested the method with datasets collected from the UN-Environment GEF project implemented in India, in which data on crop and varietal diversity were collected across seven states in India, covering five agroecological regions. Results showed that landraces are still commonly grown in the study sites, especially in the central and western regions, and that more than 50% of landraces are considered threatened, suggesting that conservation interventions are required to prevent large-scale genetic erosion. A long-term monitoring framework for varietal diversity in India is proposed.

Exploring the emergence of participatory plant breeding in countries of the Global North – a review

Participatory plant breeding (PPB), commonly applied in the Global South to address the needs of underserved farmers, refers to the active collaboration between researchers, farmers and other actors throughout the breeding process. In spite of significant public and private investments in crop variety improvement in the Global North, PPB is increasingly utilized as an approach to address cropping system needs. The current study conducted a state-of-the-art review, including a comprehensive inventory of projects and five case studies, to explore the emergence of PPB in the Global North and inform future PPB efforts. Case studies included maize (Zea mays), tomato (Solanum lycopersicum), Brassica crops (Brassica oleracea), wheat (Triticum aestivum) and potato (Solanum tuberosum). The review identified 47 projects across the United States, Canada and Europe including 22 crop species representing diverse crop biology. Improved adaptation to organic farming systems and addressing principles and values of organic agriculture emerged as consistent themes. While projects presented evidence that PPB has expanded crop diversity and farmer's access to improved varieties, obstacles to PPB also emerged including challenges in sustained funding as well as addressing regulatory barriers to the commercial distribution of PPB varieties. Agronomic improvements were only one lens motivating PPB, with many projects identifying goals of conservation of crop genetic diversity, farmers' seed sovereignty and avoidance of certain breeding techniques. The authors conclude that a multidisciplinary approach is needed to fully understand the social, political and agroecological influences driving the emergence of projects in the Global North and factors impacting success.

The Taming of Psidium guajava: Natural and Cultural History of a Neotropical Fruit

Guava (Psidium guajava L., Myrtaceae) is a Neotropical fruit that is widely consumed around the world. However, its evolutionary history and domestication process are unknown. Here we examine available ecological, taxonomic, genetic, archeological, and historical evidence about guava. Guava needs full sunlight, warm temperatures, and well-distributed rainfall throughout the year to grow, but tolerates drought. Zoochory and anthropochory are the main forms of dispersal. Guava’s phylogenetic relationships with other species of the genus Psidium are unclear. A group of six species that share several morphological characteristics are tentatively accepted as the Psidium guajava complex. DNA analyses are limited to the characterization of crop genetic diversity within localities and do not account for possible evolutionary and domestication scenarios. A significant amount of archeological information exists, with a greater number and older records in South America than in Mesoamerica, where there are also numerous historical records. From this information, we propose that: (1) the guava ancestor may have originated during the Middle or Late Miocene, and the savannas and semi-deciduous forests of South America formed during the Late Pleistocene would have been the most appropriate ecosystems for its growth, (2) the megafauna were important dispersers for guava, (3) dispersal by humans during the Holocene expanded guava’s geographic range, including to the southwestern Amazonian lowlands, (4) where its domestication may have started, and (5) with the European conquest of the Neotropics, accompanied by their domestic animals, new contact routes between previously remote guava populations were established. These proposals could direct future research on the evolutionary and domestication process of guava.

Genetic Diversity and Population Structure of Cowpea [Vigna unguiculata (L.) Walp.] Germplasm Collected from Togo Based on DArT Markers

Crop genetic diversity is a sine qua non for continuous progress in the development of improved varieties, hence the need for germplasm collection, conservation and characterization. Over the years, cowpea has contributed immensely to the nutrition and economic life of the people in Togo. However, the bulk of varieties grown by farmers are landraces due to the absence of any serious genetic improvement activity on cowpea in the country. In this study, the genetic diversity and population structure of 255 cowpea accessions collected from five administrative regions and the agricultural research institute of Togo were assessed using 4600 informative diversity array technology (DArT) markers. Among the regions, the polymorphic information content (PIC) ranged from 0.19 to 0.27 with a mean value of 0.25. The expected heterozygosity (He) varied from 0.22 to 0.34 with a mean value of 0.31, while the observed heterozygosity (Ho) varied from 0.03 to 0.07 with an average of 0.05. The average inbreeding coefficient (FIS) varied from 0.78 to 0.89 with a mean value of 0.83, suggesting that most of the accessions are inbred. Cluster analysis and population structure identified four groups with each comprising accessions from the six different sources. Weak to moderate differentiation was observed among the populations with a genetic differentiation index varying from 0.014 to 0.117. Variation was highest (78%) among accessions within populations and lowest between populations (7%). These results revealed a moderate level of diversity among the Togo cowpea germplasm. The findings of this study constitute a foundation for genetic improvement of cowpea in Togo.

Genetic Diversity in 19th Century Barley (Hordeum vulgare) Reflects Differing Agricultural Practices and Seed Trade in Jämtland, Sweden

Landrace crops are important genetic resources, both for plant breeding efforts and for studying agrarian history. The distribution of genetic diversity among landraces can reflect effects of climate, economic structure, and trade also over a limited spatial and temporal scale. In this study, we have SNP genotyped historical barley seed samples from the late 19th century, together with extant barley landrace accessions from Jämtland, Sweden, a county centrally located, situated between Sweden and Norway. We found two main genetic clusters, one associated with the main agricultural district around lake Storsjön and one in the peripheral areas. Data was also compared with genotypes from landraces from across the Scandinavian peninsula. Accessions from the peripheral part of Jämtland show genetic similarity to accessions from a large part of central Scandinavia, while the accessions from the Storsjön district are more differentiabted. We suggest that these dissimilarities in genetic diversity distribution are explained by differences in the relative importance of agriculture and trading. We further compared the historical material with ex situ preserved extant landraces from the same region and found that their genetic diversity was not always representative of the given provenience. The historical material, in contrast, proved particularly valuable for assessing how crop genetic diversity has historically been influenced by economic focus.