PI: Matthew Hudson, University of Illinois Co-PI: Stephen Moose, University of Illinois
Heterosis or hybrid vigor is a scientific term to describe the more vigorous progeny from a genetic cross between parents that are not closely related. Hybrid vigor is one of the main foundations for greatly increased crop yields during the 20th century, especially in corn (maize). However, the reasons why the offspring of a cross between distantly related individuals tend to grow larger than their parents are still poorly understood. One popular and promising hypothesis is that hybrid vigor results from a combination of genes from both parents that control growth rate and stress tolerance. Noncoding, small RNAs are recently discovered regulatory molecules encoded by genes that may fit this hypothesis. Some small RNAs are known to control shoot development and others stress-responsive genes. Preliminary experiments have shown that several small RNAs are altered in their expression in hybrid corn plants when they are compared to the inbred parents. In addition, the machinery that produces these small RNAs may also be altered in its function in hybrids when compared to inbred corn. These results also hold true in the model plant Arabidopsis, indicating that small RNA may be involved in a common mechanism of hybrid vigor in all plants. This project will investigate further the effect of small RNA on hybrid vigor in both corn and Arabidopsis, focusing on the genes that control small RNA production and on whether small RNA levels can predict the performance of different hybrid combinations of corn plants. These populations represent current and historical genetic diversity in corn, and include inbred lines that are major contributors to commercially important maize varieties. A more complete understanding of the mechanisms of heterosis, and how these mechanisms relate to the increased crop yields that result from it, is anticipated from this research.
The greater vigor observed following hybridization is one of the most easily visualized genetic effects and is commonly observed in everyday life. The use of hybrids in plant and livestock breeding has greatly increased agricultural productivity with significant benefits to global society. However, the benefits of hybrids are currently unevenly spread, with corn benefiting more than any other crop. The research will provide insight into the mechanisms of heterosis, with potential improvements in crop yields, especially in crops where hybrids do not currently provide a major increase in yield. Increased yields of major crops have the potential to reduce pressure on the environment and decrease the need to convert more wild land into agricultural land. The maize germplasm used in this project is intentionally chosen to be free from intellectual property protections and the seed are freely available from the Germplasm Resource Information Network (GRIN, www.ars-grin.gov/). Experimental lines of maize and Arabidopsis produced as part of this project will be supplied to public repositories, the maize genetics co-op (http://maizecoop.cropsci.uiuc.edu/) and the Arabidopsis Biological Resource Center (www.arabidopsis.org/abrc/). Sequence data generated will be submitted to GenBank (www.ncbi.nlm.nih.gov/Genbank/index.html) and made available on the laboratory website (http://stan.cropsci.uiuc.edu). This project will also offer a number of educational opportunities. By using commercially relevant maize germplasm in this project, graduate-level education will be more relevant to the type of research conducted in commercial seed companies, enhancing the relevance of the research to modern agriculture. Young scientists, including a summer intern, will be offered excellent opportunities to learn and apply some of the most recent advances in plant genomics research. Because heterosis is a topic of high general interest, research results will be communicated broadly through publications, presentations, and public educational efforts that emphasize the positive impacts of plant genome research. Specific examples include distribution of an educational kit of seeds that exhibit strong seedling heterosis; living demonstrations of hybrids and their inbred parents to the public via field days; presentations at high schools and community colleges and an educational web page (hosted on http://stan.cropsci.uiuc.edu and also contributed to Wikipedia) on the importance of hybrid vigor
