Genetic transformation and genome editing in wild soybean (Glycine soja)

Soybean (Glycine max), a key food and oilseed crop, is derived from wild soybean (Glycine soja). Compared with cultivated varieties, wild soybean exhibits significantly higher genetic diversity, harboring stress-tolerance genes, broad-spectrum disease-resistance genes, and superior alleles that regulate seed nutrition, which were lost during domestication. These genetic resources have remained “visible yet underutilized”, primarily due to the lack of mature transformation and gene editing systems. In this study, we established stable genetic transformation and gene editing systems for Glycine soja. We identified three major bottlenecks to the genetic transformation of Glycine soja: its thick, rigid seed coat impairs water absorption and germination; its Agrobacterium infection efficiency is low; and regenerated shoots exhibit severe chlorosis and death. To address these issues, we employed 1) seed coat sandpaper abrasion enables wild soybean seeds to absorb water and germinate within 1 d; 2) sonication at 45 kHz for 60 s, which increased the Agrobacterium infection rate from 11.76% to 55.26%; and 3) supplementation of the culture media with an additional 12 mg L⁻¹ ferrous sulfate and 30 mg L⁻¹ disodium ethylenediaminetetraacetic acid (EDTA), which alleviated chlorosis in regenerated shoots. The transformation efficiencies of two wild soybean accessions reached 1.54% and 6.33%, with stable transgene heritability. We targeted GsDELLA and successfully generated homozygous mutants, which displayed reduced plant height and branch number. We extended this approach to 19 elite soybean cultivars, obtaining positive transformants, with higher transformation efficiencies for late-maturing (MG I–VI; typically > 10%) than early-maturing (MG 00–I; 2%–10%) varieties. Our versatile transformation platform should accelerate the genetic improvement of both wild and cultivated soybean germplasm.