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

基因功能丧失是定量遗传性状响应选择的一种机制，这是本DG研究计划的基本前提。这个前提是建立在长期选择下对玉米（Zea mays L.）群体的观察基础上，建立在我的小组以前的研究基础上，并继续研究玉米数量性状的遗传结构。本提案将考察三个不同但相互关联的假设。它们的不同之处在于它们涉及非常不同的性状——淀粉合成、穗发育、叶数和开花时间。它们是相互联系的，因为它们涉及单基因功能等位基因的丧失，并且可能涉及改变分生组织的发育。具体而言：(1)短穗表型是通过积累和维持一组与穗发育有关的基因的LOF等位基因处于杂合状态，从而有效地降低这些基因的表达水平（即基因剂量），从而产生短穗表型。(2)直链淀粉扩展器1 （mae1）的修饰子是一个LOF突变，可以使直链淀粉的含量适度提高。(3)通过LOF突变的积累来选择基于叶片数与开花时间关系的茎尖分生组织（SAM）变异。本研究的影响是在应用和基础知识两个领域。它将成为2名硕士生、1名博士生和5名本科生的培训基地。这将导致以叶片数与开花时间的SAM关系为基础的新型知识产权的开发。

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.