Soyasaponin β-glucosidase confers soybean resistance to pod borer (leguminivora glycinivorella)

This study, led by Professor Guodong Wang (Institute of Genetics and Developmental Biology, Chinese Academy of Sciences), reveals how soybean plants deploy specialized metabolites to combat insect pests. The team identified GmSSBG1 (Glyma.07G258700) through co-expression analysis and initially validated its role in hydrolyzing A0/B0-series soyasaponins using hairy roots.

Subsequently, the authors performed in vitro enzymatic activity assays using purified proteins and demonstrated that GmSSBG1 specifically hydrolyzes the C-22 arabinose residues of A0- and B0-series soybean saponins. Kinetic parameter analysis revealed that this enzyme exhibits a lower K_cat value compared to several characterized β-glucosidases (BGLUs), suggesting GmSSBG1 is a relatively slow BGLU.

Further transgenic plant experiments demonstrated that both knockout and overexpression of GmSSBG1 induced significant alterations in the endogenous content of A0- and B0-series soybean saponins, confirming its in planta function in hydrolyzing these saponins. Field-based insect resistance assays revealed that ssbg1 mutants exhibited significantly reduced resistance to the legume pod borer (Leguminivora glycinivorella), with infestation rates increasing from 1.2% to 1.7-2.2%, indicating that GmSSBG1 participates in soybean defense against herbivory via modulating saponin homeostasis. 

The study bridges the gap between soyasaponin biochemistry and ecological defense mechanisms, offering novel targets for breeding insect-resistant soybean varieties. By reducing reliance on chemical pesticides, this work advances sustainable agriculture strategies.

See the article:

Soyasaponin β-Glucosidase Confers Soybean Resistance to Pod Borer (Leguminivora glycinivorella)

https://link.springer.com/article/10.1007/s42994-025-00214-7