Location: Crop Genetics and Breeding ResearchTitle: A novel QTL for root-knot nematode resistance is identified from a South African sweet sorghum line
|WALLACE, JASON - University Of Georgia|
|Knoll, Joseph - Joe|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2019
Publication Date: 2/20/2019
Citation: Harris-Shultz, K.R., Davis, R.F., Wallace, J., Knoll, J.E., Wang, H. 2019. A novel QTL for root-knot nematode resistance is identified from a South African sweet sorghum line. Phytopathology. 109(6):1011-1017. https://doi.org/10.1094/PHYTO-11-18-0433-R.
Interpretive Summary: The southern root-knot nematode (RKN) is the most common and destructive nematode species with a wide host range. Found in agricultural regions worldwide, farmers manage root-knot nematodes by nematicides, crop rotation, and the use of resistant cultivars. Sorghum is highly tolerant of RKN but some cultivars are able to increase RKN population numbers. Higher numbers of RKN in the soil increases the risk of damage to subsequently planted susceptible crops. We previously identified a major QTL for RKN resistance on sorghum Chr. 3 but for a cultivar to maintain durable resistance, multiple resistance genes should be present in a plant. In this study we identified a new source of root-knot nematode resistance, created a mapping population, and identified markers associated with egg number and egg number per g of root. We identified a single major QTL on Chr. 5 that is associated with resistance to RKN. These regions on Chr. 5 and Chr. 3, from their respective parents, can be moved into elite sorghum by crossing for durable RKN resistance.
Technical Abstract: Southern root-knot nematodes, Meloidogyne incognita, feed on the underground portions of thousands of plant species and affect nutrient partitioning and water uptake of the host plants. Sorghum (Sorghum bicolor) is highly tolerant of root-knot nematodes but some sorghum genotypes support greater population densities of root-knot nematodes than other genotypes. These higher nematode populations increase the risk of damage to subsequently planted susceptible crops. A previous study identified a major QTL for root-knot nematode resistance on sorghum Chr. 3. To maintain long-term resistance, multiple resistance genes should be pyramided in a cultivar. In this study we identified a new source of root-knot nematode resistance, created a mapping population, and identified single nucleotide polymorphisms (SNP) markers using genotyping-by-sequencing of the segregating population. Use of single marker analysis (SMA) and composite interval mapping (CIM) identified a single QTL on Chr. 5 that was associated with egg number and egg number per g of root from the resistant sweet sorghum line PI 144134. This region on Chr. 5 and the prior QTL on Chr. 3 can be potentially moved from PI 144134 and ‘Honey Drip’, respectively, into elite sorghum germplasm via marker-assisted selection for durable resistance.