Rice Genetics IV - IRRI books - International Rice Research Institute

Table 3. GUS assay in flowers of transgenic rice plants a .GUS staining patternsGUS-positiveLines (no.) %Palea/lemma 50 37.6Lodicules 8 6.0Stamens 11 8.3Carpel 4 3.0Palea/lemma, lodicules 9 6.8Palea/lemma, stamens 8 6.0Palea/lemma, carpel 5 3.8Lodicules, stamens 1 0.8Lodicules, carpel 3 2.3Stamen, carpel 9 6.8Palea/lemma, lodicules, stamens 4 3.0Palea/lemma, lodicules, carpel 2 1.5Palea/lemma, stamens, carpel 3 2.3Lodicules, stamens, carpel 1 0.8Palea/lemma, lodicules, stamens, carpel 8 6.0Rachilla 6 4.5Glumes 1 0.8Total 133 100a7,026 lines were tested.The next generation of the tagged lines is studied to determine whether these linesdisplay any mutant phenotypes in the organs where the gus gene was activated, andwhether the phenotypes cosegregate with the T-DNA.Insertional lines that exhibit a particular GUS staining pattern should facilitateidentifying genes that are regulated spatially and temporally for plant development.The Arabidopsis LRP1 (lateral root primordium1) gene, which may play a role inlateral root development, was identified by expression of promoterless gus in taggingplants (Smith and Fedoroff 1995). The Arabidopsis PROLIFERA gene, which is relatedto the MCM2-3-5 family of yeast genes, was also cloned by gene trap transposonmutagenesis (Springer et al 1995).The progeny phenotypes of the pGA1633 transgenic lines were examined. Someof the tagged lines showed mutant phenotypes, including early flowering, tallness,dwarfism, spotted leaves, chlorophyll deficiency, depressed palea, filamentous flowers,extra glumes, long sterile glumes, zebra (transverse green and chlorotic bands inleaves), etc. (data not shown). Whether any of these mutant phenotypes are due to theT-DNA insertion is under investigation.It is expected that the genome sequence of rice will be completed in the nearfuture. This will produce a large number of genes such that their identification mustbe regarded as hypothetical. One of the most efficient ways to obtain information onthe function of a gene is to create a loss-of-function mutation and study the phenotypeof the resulting mutant. If a large population of mutagenized plants is available, it ispossible to detect an insertion within the gene of interest by PCR using oligonucleotideprimers from the insertional element and the gene of interest (Couteau et al260 Gynheung An et al