Agricultural biodiversity has hitherto been valued almost exclusively as a source of traits that can be used in scientific breeding programs to improve the productivity of crop varieties and livestock breeds. We argue that it can make a far greater contribution to increased productivity. In particular, a wider deployment of agricultural biodiversity is an essential component in the sustainable delivery of a more secure food supply. Diversity of kingdoms, species and genepools can increase the productivity of farming systems in a range of growing conditions, and more diverse farming systems are also generally more resilient in the face of perturbations, thus enhancing food security. Diversity can maintain and increase soil fertility and mitigate the impact of pests and diseases. Diversity of diet, founded on diverse farming systems, delivers better nutrition and greater health, with additional benefits for human productivity and livelihoods. Agricultural biodiversity will also be absolutely essential to cope with the predicted impacts of climate change, not simply as a source of traits but as the underpinnings of more resilient farm ecosystems. Many of the benefits of agricultural biodiversity are manifested at different ecological and human scales, and cut across political divisions, requiring a cross-sectoral approach to reassess the role of agricultural biodiversity in sustainable and secure food production.

https://www.bioversityinternational.org/uploads/tx_news/Agricultural_biodiversity_is_essential_for_a_sustainable_improvement_in_food_and_nutrition_security_1405.pdf

Agricultural Biodiversity Is Essential for a Sustainable Improvement in Food and Nutrition Security

https://acsess.onlinelibrary.wiley.com/doi/pdf/10.1002/csc2.20377

Genetic diversity is indispensable for plant breeding to improve crops

Bulb onion (Allium cepa L.) is an ancient crop that is thought to have originated in Central Asia and has been cultivated for over 5000 years. Classical genetic and plant breeding approaches have been used to improve onion yield, quality, and resistance against biotic and abiotic stresses. However, its biennial life cycle, cross-pollinated nature and high inbreeding depression have proved challenging for the characterization and breeding of improved traits. New technologies, notably next-generation sequencing, are providing researchers with the genomic resources and approaches to overcome these challenges. Using these genomic technologies, molecular markers are being rapidly developed and utilized for germplasm analysis and mapping in onion. These new tools and knowledge are allowing the integration of molecular and conventional breeding to speed up onion improvement programmes. In this review, we outline recent progress in onion genomics and molecular genetics and prospects for enhancing onion yield and quality in the future.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/pbr.12330

Enhancing onion breeding using molecular tools

In this paper, we describe the development of a set of guiding principles for the evaluation of breeding techniques by the organic sector over time. The worldwide standards of organic agriculture (OA) do not allow genetic engineering (GE) or any products derived from genetic engineering. The standards in OA are an expression of the underlying principles of health, ecology, fairness and care. The derived norms are process and not product oriented. As breeding is considered part of the process in agriculture, GE is not a neutral tool for the organic sector. The incompatibility between OA and GE is analyzed, including the “novel breeding techniques”. Instead, alternative breeding approaches are pursued based on the norms and values of organic agriculture not only on the technical level but also on the social and organizational level by including other value chain players and consumers. The status and future perspectives of the alternative directions for organic breeding are described and discussed.

https://www.mdpi.com/2071-1050/9/1/18/pdf

Concepts and Strategies of Organic Plant Breeding in Light of Novel Breeding Techniques

This paper deals with the diversity assessment of tropical Indian onion and cross amplification of genomic and EST-SSR markers in distantly related native wild species. Out of 60 SSRs, 10% genomic SSRs were able to amplify as compared to EST-SSR where 53.3% primers were able to reveal amplicons. Clustering revealed five groups and indigenous short day onion formed separate cluster from the exotic short day and long day onions. A. roylei accessions exhibited a dissimilarity index of 35.5% between themselves whereas ‘Pran’ and A. × proliferum grouped together at a genetic distance of 0.4. A. fistulosum accessions formed a tight cluster and distantly related wild species A.
 carolinianum, A. chinense and A.
 hookeri formed neutral nodes. Present results are important to aid in analyzing the diversity present in short day onion and its utilization in breeding programs. Further, this is the first time that three accessions of A. roylei Stearn were used and rare alleles amplified in wild species will aid in detecting population structure and molecular marker aided selection for interspecific hybrid development.

Microsatellite marker based analysis of genetic diversity in short day tropical Indian onion and cross amplification in related Allium spp.

Downy mildew resistance originating from Allium roylei Stearn provides a complete resistance to onions and is based on one, dominant gene. Since A. roylei can successfully be hybridized with onion (A. cepa L.), a breeding scheme aimed at the introgression of this gene was initiated ca. 20 years ago. Several setbacks in this programme were encountered, firstly the identified molecular marker linked to the downy mildew resistance locus became increasingly difficult to use and finally lost its discriminating power and secondly the final step, making homozygous introgression lines (ILs), turned out to be more difficult then was hoped. GISH analysis showed that the chromosomal region harbouring the resistance locus was the only remaining piece of A. roylei in the nuclear background of onion and it also confirmed that this region was located on the distal end of chromosome 3. It was hypothesized that some factor present in the remaining A. roylei region was lethal when homozygously present in an onion genetic background. The identification of an individual with a smaller and more distally located introgression fragment and homozygous ILs in its progeny validated this hypothesis. With the help of these nearly isogenic lines four AFLP® markers closely linked to the resistance gene were identified, which can be used for marker-aided selection. The introduction of downy mildew resistance caused by Peronospora destructor into onion is a significant step forward in the development of environmentally-friendly onion cultivars.

/pdf/the-long-and-winding-road-leading-to-the-successful-3q5fax0zym.pdf

J. L. Harrewijn

Papers

The long and winding road leading to the successful introgression of downy mildew resistance into onion