Submitted to: Genes, Genomes, Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/16/2011
Publication Date: 11/1/2011
Citation: Brown, A.N., Lauter, N.C., Vera, D.L., McLaughlin-Large, K.A., Steele, T.M., Fredette, N.C., Bass, H.W. 2011. QTL mapping and candidate gene analysis of telomere length control factors in maize (Zea mays L.). Genes, Genomes, Genetics. 1(6):437-450. Interpretive Summary: Telomeres comprise repetitive DNA sequences that protect the ends of chromosomes from deterioration and/or from fusion with other chromosomes. Among other things, telomeres of a minimum length are essential for the integrity of the genetic code both during development of an individual organism and throughout evolution of a species. Many biological processes alter the regulation of telomere length, including programmed cell death. When plant cells are under attack by pathogens, they often undergo programmed cell death as a means of defense. In order to place our pathogenomics findings regarding programmed cell death into an appropriate context, it is important to understand the normal regulation and maintenance of telomere length. This study genetically identified 13 new regulators of telomere length in corn, and also tested the expression 16 genes that are likely involved with the regulation of telomere length. Future molecular characterization of the several novel mechanisms discovered will deepen our understanding of telomere length regulation, which will benefit both biological and biomedical researchers working in the disciplines of genetics, pathology, cell biology, and molecular biology.
Technical Abstract: Telomere length is under genetic control and important for essential telomere functions. Failure to regulate telomere length homeostasis contributes to cancers and aging-related diseases in animals, but the effects of telomere length defects in plants remains poorly understood. To learn more about telomere biology in plants, we carried out Quantitative Trait Locus (QTL) mapping to identify genetic elements that control telomere length in the model genetic plant species, maize (Zea mays L.). We found telomere length to be stable within different lines of maize across development, generations, and various tissues. We measured telomere lengths from 195 Recombinant Inbred Lines of the well-characterized maize intermated B73xMo17 mapping population and showed the trait to be heritable. We mapped median and mean telomere lengths and discovered several significant QTL. Collectively, genetic effects explained nearly 40% of the observed phenotypic variation, allowing several of the QTL to be localized to small enough intervals to permit candidate gene searches. The relative expression levels were evaluated for 8 QTL candidate genes (rfc, mcm7, hsp70, recq, rpa, smc5/6, parp, xrcc3) and 8 other a priori telomere length target genes (est1, iIbp2, ku70, ku80, smh3, smh4, smh6, tert). Many of the genes, such as xrcc3, showed significant correlations between telomere length and transcript abundance. At these shared genetic positions, the coincident discoveries of telomere length regulatory elements (QTLs) and genes whose expression patterns are correlated with telomere length have created a prioritized list of genes whose putative roles in telomere biology should be functionally tested.