IN SITU SUSCEPTIBILITY OF TRANSGENIC AND CONVENTIONAL RICE SEEDLING TO HYGROMYCIN B

The effects of hygromycin B on transgenic and conventional rice seedling were studied by foliar spraying. Results showed that conventional rice was susceptible to hygromycin B with toxic symptoms of brown spots in the leaves after foliar spraying. The number and area of spots increased with the time after treatment and showed concentration dependent within levels of 50～100mg/L. The toxic symptoms were enhanced with the addition of dimethyl sulfoxide (DMSO) into hygromycin B solution. All seedlings in each treatment exhibited toxic spots at the 7th day when the concentration of hygromycin B equaled to or higher than 75mg/L.However, a few seedlings did not show any toxic symptom when the concentration was 50mg/L. All of the transgenic rice with hygromycin phosphotransferase gene (hpt) was resistant to hygromycin B, none appeared any toxic symptoms over the concentrations mentioned above. Susceptibility test of rice plants to hygromycin B around heading stage showed consistent results with seedling. The applicability of foliar application of hygromycin B for screening of transgenic rice resistant/susceptive to hygromycin B was also discussed in this paper.