位于5A染色体的方穗基因Q是小麦驯化的关键基因，导致植株矮化、方穗、易脱粒等，在株型建成中发挥重要作用。Q编码一个AP2转录因子，其驯化位点发生在miR172调控区域，是一个抗miR172的AP2变异基因，但其调控小麦株型建成的分子机理尚未明晰。我们鉴定了一个位于5D上的Q同源基因发生突变的基因5Dq’，其突变位点也发生在miR172调控区域，但与5AQ发生位置不同，该突变导致矮秆密穗表型。本项目以此为基础，拟通过杂交手段和基因编辑技术，获得不同Q/q单倍型及组合，通过表型分析、显微观察和时空表达特征分析，解析不同Q基因座位在协同调控小麦株高穗型等形成中的作用，评价5Dq’新的遗传效应和育种利用价值；从AP2的DNA蛋白结合位点、不同Q组合RNA转录水平和生理生化等多个层次揭示Q基因调控株型建成的分子机理。研究结果将揭示Q在产量性状协同改良中的作用机制，为高产小麦品种选育提供理论支撑。

Q (recessive allele q) gene on chromosome 5A (5AQ) harboring free-threshing and subcompact spike of common wheat is one of key genes in wheat domestication history. Q encodes an AP2-like transcription factor. Like other AP2-like genes, Q and its homoeologs have a miR172 target site within the coding region close to the 3′ end of the gene that alters mRNA stability. Analysis of q and Q allele sequences revealed a polymorphism within the miR172 target site, implying miRNA-mediated target repression was implicated in developmental processes. Q is an essentially AP2 variant in resistance to miR172 cleavage. However, the molecular mechanism underlying Q in controlling wheat plant architecture is illusive. In our lab we have previously identified a Sumai 3 dwarf mutant NUAH164 with compact spike. Map-based gene cloning revealed a polymorphism in Q homoeologs 5Dq on chromosome 5D, which also lies within the miR172 target site. The newly mutated Q gene was designated as 5Dq’. In this project, we will performed research from two aspects. (1) We will derived various Q/q recombination for different subgenomes by hybridization experiment with Chinese Spring structural aberrant at Q/q loci or through gene editing by CRISPR/Cas9 system for different Q/q haplotypes. Based on this genetic resources, we phenotype related agronomic traits and survey the developmental processes through micro-observation. The interactive and coordinated effects among the Q/q allele will also be investigated. We will also evaluate the genetic effect of 5Dq’ for digging out its probably new function and potential application in wheat breeding. (2) To identify Q regulated genes at transcriptional levels through RNA-seq methods or Q directly targeted DNA binding sites using chromatin immunoprecipitation-based sequencing and electrophoresis mobility shift array analyses. Then, the Q mediated biological processes will be deduced and validated through physiological assessment using the above resources. This work will not only facilitate the elucidation of the molecular mechanisms underlying plant architecture determinacy regulated by Q, but also provide theory and guidance for yield improvement of crop species.