AgNO3 Promotes Callus Production and Regeneration of Immature Buffalograss Inflorescence Culture

The use of buffalograss [Buchloe dactyloides (Nutt.) Engelm] in home lawns and golf courses has been increasing because of its drought resistance and low growth habit. In vitro regeneration of buffalograss at a high frequency may provide an effective tool to introduce new variation for breeding use. The positive effects of AgNO3 on friable embryogenic callus production and regeneration efficiency is well documented in maize. In order to determine if AgNO3 has the same effect on buffalograss, two vegetatively propagated cultivars, a female `609' and a male `45-3' were tested at three different concentrations of AgNO3 at 5, 10, and 15 mg·L–1 using immature inflorescences as explants. Murashige and Skoog medium supplemented with 2 mg 2,4-D/L was employed as the control medium. Medium containing AgNO3 significantly promoted the production of friable callus for `45-3' with the highest percentage achieved at 10 mg AgNO3/L. AgNO3 medium led to production of significantly larger calli than found for the control. However, no difference was detected among 5, 10, and 15 mg AgNO3/L with regard to the callus formation ability and the size of callus initiated on these three treatments. Calli were then transferred to MS medium supplemented with BA at 0.1, 0.5 or 1.0 mg·L–1 to induce shoot formation. BA at 0.5 mg·L–1 gave the best differentiation response. Calli formed in the absence of AgNO3 produced more shoots per callus, but more calli were produced in the presence of AgNO3, and the overall regeneration efficiency was much higher with AgNO3 at 10 mg·L–1. In contrast, AgNO3 showed no promotive effect on callus production and regeneration for `609'.