| Title: | Forward genetics by genome sequencing reveals that rapid cyanide release deters insect herbivory of Sorghum bicolor |
| Author(s): | Krothapalli K; Buescher EM; Li X; Brown E; Chapple C; Dilkes BP; Tuinstra MR; |
| Address: | "Department of Agronomy, Purdue University, West Lafayette, Indiana 47907" |
| DOI: | 10.1534/genetics.113.149567 |
| ISSN/ISBN: | 1943-2631 (Electronic) 0016-6731 (Print) 0016-6731 (Linking) |
| Abstract: | "Whole genome sequencing has allowed rapid progress in the application of forward genetics in model species. In this study, we demonstrated an application of next-generation sequencing for forward genetics in a complex crop genome. We sequenced an ethyl methanesulfonate-induced mutant of Sorghum bicolor defective in hydrogen cyanide release and identified the causal mutation. A workflow identified the causal polymorphism relative to the reference BTx623 genome by integrating data from single nucleotide polymorphism identification, prior information about candidate gene(s) implicated in cyanogenesis, mutation spectra, and polymorphisms likely to affect phenotypic changes. A point mutation resulting in a premature stop codon in the coding sequence of dhurrinase2, which encodes a protein involved in the dhurrin catabolic pathway, was responsible for the acyanogenic phenotype. Cyanogenic glucosides are not cyanogenic compounds but their cyanohydrins derivatives do release cyanide. The mutant accumulated the glucoside, dhurrin, but failed to efficiently release cyanide upon tissue disruption. Thus, we tested the effects of cyanide release on insect herbivory in a genetic background in which accumulation of cyanogenic glucoside is unchanged. Insect preference choice experiments and herbivory measurements demonstrate a deterrent effect of cyanide release capacity, even in the presence of wild-type levels of cyanogenic glucoside accumulation. Our gene cloning method substantiates the value of (1) a sequenced genome, (2) a strongly penetrant and easily measurable phenotype, and (3) a workflow to pinpoint a causal mutation in crop genomes and accelerate in the discovery of gene function in the postgenomic era" |
| Keywords: | "Animals Chromosome Mapping Genome, Plant Herbivory/genetics/physiology High-Throughput Nucleotide Sequencing Hydrogen Cyanide/*metabolism Insecta/*genetics/physiology Plant Proteins/*genetics Point Mutation Sorghum/*genetics/physiology beta-Glucosidase/*g;" |
| Notes: | "MedlineKrothapalli, Kartikeya Buescher, Elizabeth M Li, Xu Brown, Elliot Chapple, Clint Dilkes, Brian P Tuinstra, Mitchell R eng Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. 2013/07/31 Genetics. 2013 Oct; 195(2):309-18. doi: 10.1534/genetics.113.149567. Epub 2013 Jul 26" |
