The tms2 gene as a negative selection marker in rice

A conditional negative selection marker is essential for high throughput insertional mutagenesis with any two-element transposon tagging system. The tms2 gene encodes indoleacetic acid hydrolase (IAAH) which converts naphthaleneacetamide (NAM) to the potent auxin naphthaleneacetic acid, a phytotoxic derivative. This gene, under the control of the manopine synthase gene 2 promoter from Agrobacterium tumefaciens and exogenously applied NAM, have been used effectively as a negative selector in Ac/Ds insertional mutagenesis of Arabidopsis thaliana (Sundaresan et al., 1995). In this study we show that tms2 can also be used as a negative selector in rice. T-1 transgenic seedlings expressing this tms2 gene under the control of the mas2' promoter showed significant reduction in shoot and root growth in the presence of 5-10 muM NAM under specified growth conditions compared to plants not containing this gene.