Reducing the threat of Sunn Pest
A groundbreaking study is the first to identify a major locus for resistance to Sunn Pests at the vegetative stage of crop growth. This could provide a critical building block in the development of resistant wheat varieties, and a practical and cost-effective strategy to strengthen food security in Eastern Europe and West and Central Asia.
Sunn pest is one of the most destructive insect pests of bread and durum wheat in Eastern Europe and West and Central Asia. Infestation of wheat fields causes stunting, floret abortion, and the shriveling of kernels. Yield losses of up to 50-90 percent are common. The insect also injects a proteolytic enzyme during feeding, which breaks down gluten and compromises the quality of baking flour.
Management strategies exist, but these usually involve chemical forms of control – which are costly, unsustainable, and over time result in growing resistance to insecticides. Integrated pest management strategies - comprising biological control, cultural practices, and host plant resistance – are more cost-effective and sustainable.
Although genetic variation for resistance to Sunn pest has been identified in wheat, no information yet exists on the chromosome location of genetic factors that underlie this resistance at vegetative stage to Sunn pest feeding. Without this information, the task of breeding Sunn pest-resistant wheat varieties becomes that much harder.
Identifying the major locus of resistance
Scientists from the New South Wales Department of Primary Industries (Australia) and ICARDA addressed this knowledge gap. The team used phenotypic data of Sunn pest screening carried out at ICARDA’s station in Terbol, Lebanon, and genotyping data with single nucleotide polymorphisms (SNPs) –genetic variations at a single position in the DNA sequence of different lines. When associated with a trait, scientists may use the information to identify the gene or genes responsible for the trait variations.
The study identified a single genetic locus on the short arm of chromosome 4B with a significant impact on resistance to Sunn pest feeding at the vegetative stage, which demonstrated impressive stability in different genetic backgrounds. SNP markers closest to the locations of peak Sunn pest resistance were then converted into breeder-friendly formats, and this utility for selecting resistance was validated in a large population of wheat cultivars, landraces, and synthetic lines.
A novel breakthrough
This is the first report of a major locus being associated with Sunn pest resistance at the vegetative stage, which could prove to be a major breakthrough in efforts to breed resistant wheat varieties that are able to withstand the destructive impacts of Sunn pest. Communities and farmers who regularly struggle to contain this threat could now have a useful resource to fight back.
This article is based on a scientific paper – ‘QTL mapping identifies a major locus for resistance in wheat to Sunn pest feeding at the vegetative growth stage’ - recently published in Theoretical and Applied Genetics.
Author: Mustapha El-Bouhssini, Entomologist (ICARDA).