Role of microRNA-related Polymorphisms in Regulating Heterotic Gene Expression

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PI: Lei Li (University of Virginia)Heterosis (hybrid vigor) refers to the phenomenon that progeny of diverse inbred parent exhibits superior traits to either of the two parents. This phenomenon has been extensively exploited in plant breeding and crop improvement. Although several genetic concepts have long been used to explain heterosis, they are not yet connected with molecular principles and thus offer limited mechanistic insight. The goal of this project is to investigate the role of microRNA-mediated gene circuits, which regulate many plant developmental processes, in heterosis in the rice plant. This work will utilize the rice genome sequences, high throughput experimental techniques, bioinformatic tools, and molecular techniques to examine 1) how microRNA-related polymorphisms between two parental rice strains contribute to differential gene expression in their hybrids, and 2) whether manipulation the expression levels of key microRNA genes impacts heterotic phenotypes. Through this project, a set of microRNA genes and their target genes involved in heterosis will be identified. Knowledge gained from this research should provide a framework necessary to understand the role of microRNA-mediated molecular events in the expression of heterosis and thus a foundation for further engineering the phenomenon in crop improvement. The broader impacts of this project stem in part from the yield advantage and other superior traits of hybrid-based crop production. Understanding the contribution of microRNA-regulated gene circuits to heterosis in the model plant rice is of great importance to food security worldwide. A comprehensive set of experimentally tested microRNA genes in rice will be made available to the public through established microRNA databases (http://microrna.sanger.ac.uk/) and rice annotation databases (http://rice.plantbiology.msu.edu/). Such information will provide new insights into microRNA-mediated gene regulation and add to our general knowledge of plant genome expression and regulation. Given that rice is a model for the grass species, information obtained from this project should facilitate comparative genomics studies aimed at tracing evolution of microRNA-regulated gene circuits in other food, feed and energy crops. The broader impacts of this project also include excellent training opportunities in the interdisciplinary field of plant genomics and bioinformatics. By blending classroom lectures with computational experimentation, information generated from this project will be particularly useful to encourage undergraduate students to actively participate in independent research.