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Title: COMPARATIVE EXPRESSION ANALYSIS OF TWO SUGARCANE POLYUGIQUITIN PROMOTERS AND FLANKING SEQUENCES IN TRANSGENIC PLANTS

Author
item WEI, HAIRON - UNIV OF HAWAII
item WANG, MING-LI - HI AG RESEARCH CNTR
item MOORE, PAUL
item ALBERT, HENRIK

Submitted to: Journal of Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2003
Publication Date: 5/1/2003
Citation: Wei, H., Wang, M., Moore, P.H., Albert, H.H. 2003. Comparative expression analysis of two sugarcane polyugiquitin promoters and flanking sequences in transgenic plants. Journal of Plant Physiology. 160(10):1241-1251.

Interpretive Summary: Two polyubiquitin promoters from sugarcane were tested in transgenic rice and sugarcane. Transgenic rice lines produced high levels of transgene expression throughout the plant body, and this high level was maintained in the progeny of the primary transgenic lines. In sugarcane, high levels of transgene expression were observed in undifferentiated cells, however all plant lines showed greatly decreased transgene expression after plant regeneration. This transgene silencing was not specific for the sugarcane polyubiquitin promoters, but also occurred with a positive control promoter. These promoters constitute useful tools for research and crop improvement for some monocot plants like rice. In other monocots like sugarcane, methods to control transgene silencing must be developed to utilize these or other promoters effectively.

Technical Abstract: GUS (uidA) reporter gene expression for two sugarcane polyubiquitin promoters, ubi4 and ubi9, was compared to expression from the maize Ubi-1 promoter in stable transgenic rice (only ubi9) and sugarcane (ubi4 and ubi9). Ubi9 drove high-level GUS expression, comparable to the maize Ubi-1 promoter, in both callus and regenerated plants of rice transformed by Agrobacterium. This high level expression was inherited in R1 plants. Expression from ubi4 and ubi9 was quite high in sugarcane callus transformed via particle bombardment. Expression dropped to very low or undetectable levels in resulting plants; this drop in expression resulted from PTGS. PTGS in regenerated sugarcane plants also occurred with the maize Ubi-1 promoter. In sugarcane callus, ubi4 was HS inducible, but ubi9 was not. This physiological difference corresponds to a MITE insertion that is present in the putative HSEs of ubi9 but not present in ubi4.