小麦脆秆基因的图位克隆和功能解析

Wheat culm strength, is an agronomically important trait that tightly associated with grain yield and stress resistance. Investigating the genetic mechanism underlying the cell wall biosynthesis and modification is one of the prerequisites for cultivation of new germplasms with higher lodging resistance and straw conversion efficiency. However, little is known about the biochemical and genetic basis of physicochemical properties of wheat straw. We have selected nine brittle culm mutants from the pools of E’mai 596 and Zhengmai 9023 mutagenized with ethyl methanesulfonate (EMS). A preliminary analysis was done comparing the differences between brittle culm and wild types in agronomic traits, physical-chemical properties and cell wall composition of wheat straws. Genetic analysis of six out of nine populations we constructed showed that brittle culm all caused by single gene mutations and currently transcriptomic BSA (BSR-seq) and SSR-BSA is being utilized in finding the molecular markers linked to target genes. This application aims to further characterize the fine structure, components and their chemical bond linkages of the brittle culm cell wall using the techniques such as gas chromatography-mass spectrometry(GC-MS), atomic force microscopy (AFM), X-ray diffraction and nuclear magnetic resonance (NMR), and to find the key factors affecting the culm properties including lodging resistance and enzymatic digestibility for bioenergy purpose. In addition, two mutants (wbc2 and wbc3) will be subject to gene map-based cloning and functional analysis of their roles in cell wall biosynthesis and regulation. It’s will be helpful to the genetic improvement of the straw relevant traits in wheat breeding.

作物茎秆强度是重要农艺性状，与产量、抗性等密切相关。目前对小麦茎秆理化性质及其细胞壁合成调控机理知之甚少。项目前期创建并筛选了鄂麦596和郑麦9023的EMS突变体库，获得9个脆秆突变体，初步分析了其与野生型在农艺性状、细胞壁组成和秸秆理化性质方面的差异，完成了转录组测序，构建了群体并利用转录组BSA（BSR-seq）和SSR-BSA筛选与目标基因连锁的分子标记并初步定位。本项目拟在此基础上，利用气质联用、原子力显微镜、X-ray衍射和核磁共振等技术，深入分析小麦突变体细胞壁多糖组分、纤维素结晶特征和木质素单体链接方式等精细构成，重点探讨其与秸秆力学特征和酶解产糖效率的关系，揭示关键的细胞壁因子。同时，选取其中单基因遗传的显性和隐性突变体各一个（wbc2和wbc3）进行基因图位克隆，重点研究其在小麦细胞壁合成调控中的功能，阐述茎秆理化性质形成分子机理，为遗传改良提供依据。

作物倒伏是一个重要的生产问题。茎秆倒伏是其中的一种类型，目前对其遗传机理尚不明确。本项目前期在普通小麦中发现了一个脆秆材料。由于目前在小麦中没有见到脆秆基因的报道，项目连续多年多点比较研究了脆秆小麦的农艺学性状、机械力学及其细胞壁特征和酶解转化效率。并综合运用各种技术，深入分析了小麦突变体细胞壁多糖组分、纤维素结晶特征、木质素单体链接方式和大小维管束数目和分布等化学组成和精细结构，重点探讨了其与秸秆力学特征、酶解产糖效率和重金属镉吸收的关系，揭示关键的细胞壁因子，具有重要创新和科学意义。在此基础上，构建遗传群体，利用SSR分子标记、BSA-seq和BSR-seq等技术开展图位克隆，已进行精细定位并克隆相关基因，已获得相关基因的突变体和遗传编辑材料，为最终解析脆秆形成原因和小麦细胞壁合成调控机理建立了坚实基础。本项目结果可为小麦秸秆的理化性质改了提供理论依据、技术方案和基因资源，具有潜在的应用价值。