Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2015
Publication Date: 8/4/2015
Citation: Harris-Shultz, K.R., Davis, R.F., Knoll, J.E., Anderson, W.F., Wang, H. 2015. Inheritance and identification of a major quantitative trait locus (QTL) that confers resistance to Meloidogyne incognita and a novel QTL for plant height in sweet sorghum. Phytopathology. 105(12):1522-1528.
Interpretive Summary: Southern root-knot nematodes (Meloidogyne incognita) parasitize thousands of plant species causing economic losses especially on row crops and vegetable species. Management of nematodes includes nematicides, plant resistance, and cultural practices such as crop rotation. The use of resistant sorghum in crop rotation can reduce the number of nematodes for the next susceptible crop. In this study, an area on Chromosome 3 was identified from the resistant sweet sorghum cultivar ‘Honey Drip’ that controls resistance to southern root-knot nematodes. Easy to use markers were developed so that this region can be selected for in the creation of resistant sorghum lines for grain, forage, or bioenergy.
Technical Abstract: Southern root-knot nematodes (Meloidogyne incognita) are a pest on many economically important row crop and vegetable species and management relies on chemicals, plant resistance, and cultural practices such as crop rotation. Little is known about the inheritance of resistance to M. incognita or the genomic regions associated with resistance in sorghum (Sorghum bicolor (L.) Moench). In this study, an F2 population (N=130) was created between the resistant sweet sorghum line ‘Honey Drip’ and the susceptible sweet line ‘Collier’. Each F2 plant was phenotyped for stalk weight, height, juice Brix, root weight, egg number, and egg number per g of root. Strong correlations were seen between egg number per g of root and egg number, height and stalk weight, and between two measurements of Brix. Selective genotyping using genotyping by sequencing was used to generate single nucleotide polymorphism (SNP) markers. The G-Model, single marker analysis, interval mapping, and composite interval mapping were used to identify a major quantitative trait locus (QTL) on Chromosome 3 for egg number and eggs per g of root. Furthermore a new QTL for plant height was also discovered on Chromosome 3. Simple sequence repeat (SSR) markers were developed in the egg number and egg number per g of root QTL region and the markers flanking the resistance gene are 4.7 and 2.4 cM away. These markers can be utilized to move the southern root-knot nematode resistance gene from ‘Honey Drip’ to any sorghum line.