Rice Genetics IV - IRRI books - International Rice Research Institute

Although mutants with discrete genetic lesions are ideal genetic materials forassigning function to a particular gene, there are only two possible alleles at a locus ineach parental genotype. The success of a mutant screening therefore depends on discriminatingthe phenotypic effect of changing a single allele. Some mutated allelesmay not have observable phenotypes because of minor effects or gene redundancy.The production of double or triple mutants is probably needed to understand the effectsand interactions of multiple genes. Even after a sequence is assigned to a mutantby reverse genetics, phenotyping, possibly guided by the known disrupted sequence,remains the critical step for assigning function. With the availability of genetic toolsand sequence information, ample opportunities exist to make use of the allelic diversitycreated in mutants together with the natural variability present in breeding materialsand raw germplasm to better understand the pathways that control complex traits.ReferencesAguirrezabalaga I, Nivard MJM, Comendador MA, Vogel EW. 1995. The cross-linking agenthexamethylphosphoramide predominantly induces intra-locus and multi-locus deletionsin postmeiotic germ cells of Drosophila. Genetics 139:649-658.Bruggemann E, Handwerger K, Essex C, Storz G. 1996. Analysis of fast neutron-generatedmutants at the Arabidopsis thaliana HY4 locus. Plant J. 10:755-760.Clough SJ, Fengler KA, Yu I-c, Lippok B, Smith Jr. RK, Bent AF. 2000. The Arabidopsis dnd1“defense, no death” gene encodes a mutated cyclic nucleotide-gated ion channel. Proc.Natl. Acad. Sci. USA 97:9323-9328.Colbert TG, Till BJ, Tompa R, Reynolds SH, Steine MN, Yeung AT, McCallum CM, Comai L,Henikoff S. 2001. High-throughput screening for induced point mutations. Plant Physiol.(In press.)Krysan PJ, Young JC, Tax F, Sussman MR. 1996. Identification of transferred DNA insertionswithin Arabidopsis genes involved in signal transduction and ion transport. Proc. Natl.Acad. Sci. USA 93:8145-8150.Leister D, Kurth J, Laurie DA, Yano M, Sasaki T, Devos K, Graner A, Schulze-Lefert P. 1998.Rapid reorganization of resistance gene homologues in cereal genomes. Proc. Natl. Acad.Sci. USA 95:370-375.Liu LX, Spoerke JM, Milligan EL, Chen J, Reardon B, Westlund B, Sun L, Abel K, ArmstrongB, Hardiman G, King J, McCague L, Basson M, Clover R, Johnson CD. 1999. Highthroughputisolation of Caenorhabditis elegans deletion mutants. Genome Res. 9:859-867.Martienssen RA. 1998. Functional genomics: probing plant gene function and expression withtransposons. Proc. Natl. Acad. Sci. USA 95:2021-2026.McCallum CM, Comai L, Green EA, Henikoff S. 2000a. Targeting induced local lesions ingenomes (TILLING) for plant functional genomics. Plant Physiol. 123:439-442.McCallum CM, Comai L, Green EA, Henikoff S. 2000b. Targeted screening for induced mutations.Nature Biotechnol. 18:455-457.Okubara PA, Anderson PA, Ochoa OE, Michelmore RW. 1994. Mutants of downy mildewresistance in Lactuca sativa (lettuce). Genetics 137:867-874.Oleykowski CA, Bronson Mullins CR, Godwin AK, Yeung AT. 1998. Mutation detection usinga novel plant endonuclease. Nucleic Acids Res. 26:4597-4602.250 Leung et al