biologia plantarum

Biologia plantarum 49:577-583, 2005 | DOI: 10.1007/s10535-005-0052-3

Expression of a Bacillus subtilis protoporphyrinogen oxidase gene in rice plants reduces sensitivity to peroxidizing herbicides

Y. I. Kuk¹, H. J. Lee^2,*, J. S. Chung³, K. M. Kim⁴, S. B. Lee⁵, S. B. Ha⁵, K. Back⁵, J. O. Guh³

¹ Biotechnology Research Institute, Chonnam National University, Gwangju, Korea

² School of Plant Science, Seoul National University, Seoul, Korea

³ Faculty of Applied Plant Science, Chonnam National University, Gwangju, Korea

⁴ Scigen Harvest Research Center, Suwon, Korea

⁵ Department of Genetic Engineering, Chonnam National University, Gwangju, Korea

Protoporphyrinogen oxidase (Protox) in the porphyrin pathway is the target site of the peroxidizing herbicides such as carfentrazone-ethyl and oxyfluorfen. In an attempt to develop herbicide-resistant plants, transgenic rice plants were generated via expression of herbicide-insensitive Bacillus subtilis Protox gene fused to the transit sequence for targeting to the plastid using Agrobacterium-mediated gene transformation. Homozygous transgenic rice lines of T₃ generation selected by hygromycin resistance test were examined if they are resistant to the herbicides carfentrazone-ethyl and oxyfluorfen. The homozygous transgenic lines had single copy insertion of B. subtilis Protox gene into their genomes and express its mRNA. Compared to wild-type rice, the transgenic lines were less susceptible to the herbicides when examined with respect to growth, electrolyte leakage, chlorophyll loss and lipid peroxidation. The in vitro Protox activities in transgenic lines were about 56 % higher than those in wild-type rice. With 10 µM concentration of the herbicides in the enzyme assays, Protox activities in transgenic lines were similar to those in non-inhibited wild-type rice. Less amount of protoporphyrin IX was accumulated in transgenic lines than in wild-type rice upon the treatment of the herbicides at 10 µM concentration. Our results indicated that expression of B. subtilis Protox gene was stably transmitted into T₃ rice plants and reduced their sensitivity to carfentrazone-ethyl and oxyfluorfen.

Keywords: gene transformation; herbicide resistance; lipid peroxidation; porphyrin pathway

Subjects: Agrobacterium tumefaciens; Bacillus subtilis; carfentrazone-ethyl; herbicide, resistance, sensitivity; lipid peroxidation; Northern blot analysis; Oryza sativa; oxyfluorfen; peroxidizing herbicides; porphyrin pathway; protoporphyrinogen oxidase; rice, transgenic, herbicide resistance; Southern blot analysis; transgenic plants

Received: December 8, 2003; Accepted: April 15, 2005; Published: December 1, 2005  Show citation