Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/11/2010
Publication Date: 1/1/2010
Citation: Saha, G., Sarker, A., Chen, W., Vandemark, G.J., Muehlbauer, F.J. 2010. Inheritance and linkage map positions of genes conferring resistance to stemphylium blight in lentil. Crop Science. 50 (5):1831-1839. Interpretive Summary: Stemphylium blight is one of the major diseases of lentil (Lens culinaris Medik.) in South Asia and North America. Because lentils have a relatively low value on a per-acre basis, the application of fungicides for controlling this and other diseases caused by fungi is not an economically viable method for disease control. The control method most preferred by growers is the cultivation of improved varieties that have genetic resistance to a wide portfolio of different diseases. The development of varieties with improved disease resistance is greatly impacted by the ability of plant breeders to easily and accurately screen plants and identify resistant materials. A major difficulty in screening for resistance in lentils to Stemphyllium blight is that the pathogen cannot be cultured in growth media, which requires the reliance on naturally occurring inoculum for initiating disease in screening nurseries. Years in which inoculum are not present in adequate levels result in an inability to accurately identify resistant materials. An alternative approach to directly screening for disease resistance would be to identify DNA markers associated with resistance and use these DNA markers for subsequent identification of resistant lines. Our objective was to identify molecular markers that were associated with resistance in lentil to Stemphyllium blight. A lentil population that exhibited differences among plants in disease resistance was screened in the field for two years. We identified a total of three DNA markers that were significantly associated with resistance to Stemphyllium blight over both years. In the immediate future we will examine the utility of these markers for accelerating the development of improved lentil varieties.
Technical Abstract: Stemphylium blight (caused by Stemphylium botryosum Wallr.) is one of the major diseases of lentil (Lens culinaris Medik.) in South Asia and North America. The objective of the study was to identify linkage map position of the genes conferring resistance to stemphylium blight and the markers linked to the genes for its utilization in marker assisted breeding. A population of 206 F7 derived recombinant inbred lines (RILs) was developed from a cross between ILL-6002 (resistant) and ILL-5888 (susceptible). The RILs were planted in disease screening plots at Ishurdi, Bangladesh in the 2006-2007 and 2008-2009 winter cropping seasons. Significant variation was detected among RILs for disease scores and frequency distributions suggested complex inheritance. An intraspecific linkage map was constructed that comprised 139 markers; 21 Simple Sequence Repeats (SSR), 27 Randomly Amplified Polymorphic DNA (RAPD), 89 Sequence Related Amplified Polymorphism (SRAP) markers and 2 morphological markers distributed over 14 linkage groups. One significant QTL was detected based on disease scores from the 2006-2007 experiment while three significant QTLs were detected from the 2008-2009 experiment. The QTL QLG480-81 was common in both years and accounted for 25.2% and 46.0% of the variation of disease scores in 2006-2007 and 2008-2009 experiments, respectively. Two SRAP markers, ME5XR10 and ME4XR16c, and one RAPD marker, UBC34, located on linkage group 4, were significantly associated with the QLG480-81 in both crop years. After validation, the more tightly linked ME4XR16c marker may be used for marker assisted selection for stemphylium blight resistance.