A Broad Review of Soybean Research on the Ongoing Race to Overcome Soybean Cyst Nematode

SIMPLE SUMMARY: The cultivated soybean [Glycine max (L.) Merr.] is an economically important crop worldwide and is regularly used for protein and oil in human consumption, animal feed, industrial products and as an important element in sustainable agricultural management practices due to its nitrogen fixation capability. Soybean cyst nematode, Heterodera glycines Ichinohe, is a plant parasitic nematode which is an overwhelming pest of soybean on a global scale. So far, soybean growers are limited to the soybean cultivars that can be planted in infested fields due to the lack of resistant genes identified against this pathogen. In this paper, we review a broad range of approaches which have been utilized in the race to understand the plant’s response to this nematode and the mechanisms of resistance, as well as to shed light onto the areas that need to be further investigated. The purpose of this review is to summarize the information that breeders and molecular biologists can use to better understand the host–pathogen relationship in the hopes of overcoming this devastating nematode. ABSTRACT: Plant pathogens greatly impact food security of the ever-growing human population. Breeding resistant crops is one of the most sustainable strategies to overcome the negative effects of these biotic stressors. In order to efficiently breed for resistant plants, the specific plant–pathogen interactions should be understood. Soybean is a short-day legume that is a staple in human food and animal feed due to its high nutritional content. Soybean cyst nematode (SCN) is a major soybean stressor infecting soybean worldwide including in China, Brazil, Argentina, USA and Canada. There are many Quantitative Trait Loci (QTLs) conferring resistance to SCN that have been identified; however, only two are widely used: rhg1 and Rhg4. Overuse of cultivars containing these QTLs/genes can lead to SCN resistance breakdown, necessitating the use of additional strategies. In this manuscript, a literature review is conducted on research related to soybean resistance to SCN. The main goal is to provide a current understanding of the mechanisms of SCN resistance and list the areas of research that could be further explored.