An innovative method for counting females of soybean cyst nematode with fluorescence imaging technology

Use of resistant cultivars is one of the major tactics for combating soybean cyst nematode, Heterodera glycines Ichinohe, which is the most destructive pathogen affecting soybean seed production. However, developing new H. glycines-resistant soybean cultivars is a very labor-intensive process, partially due to the lack of a quick method for counting the H. glycines females that develop on soybean roots. We have developed a fluorescence image-based system for counting females on excised seedling roots cultured on nutrient media in petri dishes. In this system, the females fluoresced when exposed to a wavelength of 570 nm. The fluorescent images were captured with a digital camera, transferred to a computer, and displayed on a monitor. The image of an entire sample was viewed at once, and the fluorescing females were counted manually. This system significantly improved the efficiency and accuracy of counting females developed on cultured seedling roots compared to a microscope counting method. The potential for applications in the screening of nematode-resistant crops is discussed.