Generating Transgenic Soybean Composite Plants

The wild-type GmSnRK1, GmNodH genes and their mutants were cloned into plant binary vectors. GmSnRK1 (K49M) is a kinase-dead mutant [21 (link)] and is used as a negative control. The constructs were transformed into Agrobacterium rhizogenes strain K599. The soybean (Williams 82) seeds were germinated in wet vermiculite and the seedlings were grown under conditions of 16-h light and 8-h dark photoperiod, 28 °C, and 80% soil moisture. When the cotyledons are fully opened and the shoots reach about 5 cm in height, a drop of A. rhizogenes culture (OD₆₀₀ = 0.6–0.8) was injected into hypocotyls using a sterile syringe needle. The inoculated seedlings were covered with transparent Saran film to keep humidity and grown under the same conditions as above. After 15-day growth, the primary roots were removed from seedlings to induce the hairy roots when the hairy roots emerged. The plants with transgenic hairy roots are called composite plants.