Plant, Animal & Microbe Genomes X Conference Plant, Animal & Microbe Genomes X ConferenceJanuary 12-16, 2002
Town & Country Convention Center
San Diego, CA
Workshop: ICSB
Transgene expression levels in 38 independent field-grown transgenic sugarcane lines were examined to assess the feasibility of using sugarcane as a biofactory system. Twenty-five of these lines were transformed with GUS genes under the control of four different promoters and the remaining 13 lines were transformed with invertase genes under the control of the maize ubiquitin-1 (Ubi-1) promoter. In all of these lines, the transgene expression was greatly reduced after plant regeneration. The results of nuclear run-on experiments and the presence of small interfering RNA (siRNA) in some of the GUS lines indicates that the reduced expression was due to post-transcriptional gene silencing. Recently sugarcane lines were transformed to produce the human cytokine granulocyte macrophage colony stimulating factor (GM-CSF). Two promoters, Ubi-1 and sugarcane ubiquitin-9 (ubi9), were used. The signal peptide sequence from potato proteinase inhibitor II was used to direct GM-CSF secretion into the apoplast. The ER retention signal, HDEL, and a histidine tag were added in some of the constructs. More than 400 putative transgenic lines have been generated for 2 varieties, H62-4671 and Q117. Out of the 50 plants screened, 18 of the 40 PCR positive lines are also western positive. Quantitative estimation of expression level using ELISA is underway.