Research Progress on Pathogen Classification and Resistance QTL of Soybean Root Rot

Soybean〔Glycine max (L.) Merr.〕is not only an important grain and oil crop and economic crop in China, but also provides high-quality plant protein for the human body. Soybean root rot is a worldwide soil-borne disease that causes root rot in soybeans. The main pathogens include Phytophthora sojae, Fusarium spp. and Pythium spp.. Root rot can affect the entire life cycle of soybean production, resulting in severe yield losses. Moreover, the diversity of pathogen populations is significant, and the geographical distribution varies significantly: Fusarium spp. are predominant in Heilongjiang and Shandong provinces in China, while P. sojae and F. oxysporum are mainly responsible for the combined infection in Fujian province. After infection, pathogens destroy host defenses by secreting toxins (such as Fusarinic acid), effector proteins (RXLR), and cell wall degrading enzymes, and weaken the effectiveness of chemical control through drug resistance evolution. At the same time, the plant immune system activates the PTI/ETI immune response through the PRR-NLR two-tier recognition mechanism, and forms a multi-layered defense network through cross-regulation of SA and JA hormone signals and epigenetic modification. In addition, genetic studies on root rot resistance have identified multiple major QTLs, such as Fusarium resistance-related QTLs (Chr08, 19), Phytophthora Rps gene clusters (Chr03, 13, 18), and Pythium resistance QTLs (Chr06, 20). This paper reviews the pathogenic species, damage symptoms, defense mechanisms of plants after infection with pathogenic bacteria, and the research progress on resistance QTLs of different soybean root rot pathogens. It discusses the deficiencies and future development of soybean root rot resistance breeding, providing valuable references for the formulation of disease resistance breeding strategies in the future.