Genetic Mechanisms Underlying Quantitative Traits in Maize – Dosage Effects & Loss of Function Mutations

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Loss of gene function is a mechanism by which quantitatively inherited traits respond to selection is the underlying premise of this DG research proposal. This premise was built on observations made while working with a maize Zea mays L.) population under long-term selection, builds upon my group’s previous research, and continues the examination of genetic architecture underlying quantitative traits in maize. Three distinct yet interconnected hypotheses will be examined in this proposal. They are distinct in that they involve very different traits – starch synthesis, ear development, leaf number and flowering time. They are connected in that they involve single-gene loss of function alleles and are potentially involved in altering meristem development. Specifically: (1) The short-ear phenotype was achieved by accumulating & maintaining a set of LOF alleles for genes involved in ear development in a heterozygous state thus effectively reducing the level of expression of these genes (i.e., gene dosage) and resulting in a short-ear phenotype. (2) Modifier of amylose extender 1 (mae1) is a LOF mutation that confers a moderately higher level of amylose. (3) Selection for an altered shoot apical meristem (SAM) based relationship between leaf number and flowering time will be achieved through the accumulation of LOF mutations. Impact of this research is both in the applied and basic knowledge arenas. It will serve as a training ground for 2 M.Sc. students, 1 Ph.D. student, and 5 undergraduate students. And it will lead to the development of novel intellectual property in the form of maize germplasm exhibiting altered SAM based relationship between leaf number and flowering time.