An integrated approach to stabilising HFN in wheat: screens genes & understanding

该项目的目的是提高小麦主要品质性状哈格伯格降落值（HFN）的稳定性。HFN目前对一些环境条件很敏感，这些条件降低了谷物的质量，使其不适合制作面包，导致农民遭受严重的经济损失：去年（2004年），英国用于制作面包的小麦作物中只有27%的质量合格，估计农民每英亩小麦种植的损失为100英镑。英国品种在他们的易感性低HFN不同，部分原因是由于传统的表型筛选育种选择的大群体的困难，但一些（如。选择，马六甲）显然携带足够的遗传抗性。HFN的推荐列表评分依赖于触发潜在易感性的适当天气条件的发生或引发收获前发芽的高架灌溉（McVittie J &德雷珀S（1982））或冬小麦立地块的灌溉，以评估收获前发芽的品种倾向。J. Natn. Inst. Bot. 16：45-48）。该项目的一个主要目的是提供新的工具和生物学见解，使育种者能够从英国现有的精英种质库中识别具有稳定HFN的新品系。现有的抗性品种在田间播种中不表现出出苗问题，这一事实表明，这一目标与迅速建立林分是一致的。申请人先前的研究已经表明，UK谷物中高α-淀粉酶水平的两个最重要的原因是收获前发芽（PHS）和早熟α-淀粉酶（PMA）。小穗病是穗中谷物过早发芽的结果，在成熟和收获之间的时期，潮湿的天气促进了易感品种的发芽。随后α-淀粉酶分泌到淀粉质胚乳中导致谷粒品质的劣化，这通过HFN测试来测量。PMA的定义不太明确，但据信是由于胚乳折痕区糊粉层在籽粒发育后期不适当地产生α-淀粉酶所致。在BBSRC资助的LINK项目中，我们打算研究小麦籽粒中的生物化学和分子事件，这些事件是PHS和PMA期间减少HFN的原因。来自模式物种的分子遗传信息将用于提供与发芽潜力/胚乳发育相关的“候选基因”。这些将用于PHS/PMA相关种子开发期间的功能测试。现有种质中候选基因的表达特征和遗传变异的表征，以及“智能筛选”和经验证的遗传标记的开发，将为英国小麦育种者提供资源，以创造具有更稳定HFN的改良品种。该项目将涉及BBSRC综合生物学和可持续农业战略计划目标的几个组成部分，包括“功能和比较基因组学”，“综合生物学-植物”，“转录组学”，“全生物生物学”和“可持续农业”。它的目标是提供一个“管道”，将从模式物种研究中获得的信息传递到用于提高育种种质的工具，这是最近BBSRC作物科学评论的一个关键建议。

The aim of this project is to improve stability of the Hagberg Falling Number (HFN), a major quality trait in wheat. HFN is currently sensitive to a number of environmental conditions that reduce the quality of grain and make it unsuitable for bread-making, resulting in severe financial losses to farmers: last year (2004) only 27% of the UK wheat crop grown for bread-making was of acceptable quality, with an estimated loss to farmers of £100 per acre of wheat grown. UK cultivars vary in their susceptibility to low HFN, partly due to the difficulty of applying conventional phenotypic screens to large populations of breeding selections, but some (eg. Option, Malacca) evidently carry adequate genetic resistance. Recommended List scores for HFN rely on the occurrence of appropriate weather conditions to trigger latent susceptibility or overhead irrigation to provoke pre-harvest sprouting (McVittie J & Draper S (1982) or irrigation of standing plots of winter wheat in order to assess varietal predisposition to pre-harvest sprouting. J. Natn. Inst. Bot. 16: 45-48). A key aim of this project is to furnish new tools and biological insights to enable breeders to identify new lines with stable HFN from the available pool of elite UK germplasm. The fact that existing resistant cultivars do not manifest problems with emergence in field sowings indicates that this aim is compatible with prompt stand establishment. Previous research by the applicants has shown that the two most important causes of high alpha-amylase levels in UK grain are pre-harvest sprouting (PHS) and pre-maturity alpha-amylase (PMA). PHS is the result of premature germination of grain in the ear, promoted in susceptible varieties by wet weather in the period between maturity and harvest. The consequent secretion of alpha-amylases into the starchy endosperm results in the deterioration in grain quality that is measured by the HFN test. PMA is less well defined, but is believed to result from inappropriate production of alpha-amylases by the aleurone layer in the crease region of the endosperm, late in grain development. Within the BBSRC financed objectives of this LINK project we intend to study the biochemical and molecular events in the wheat grain that are responsible for reduction of HFN during both PHS and PMA. Molecular genetic information from model species will be used to provide 'candidate genes' associated with germination potential/ endosperm development. These will be used for testing of function during seed development in relation to PHS/PMA. The characterisation of expression characteristics and genetic variation of candidate genes in existing germplasm, and the development of 'smart screens' and validated genetic markers will provide UK wheat breeders with resources to create improved varieties with more stable HFN. This project will address several components of the BBSRC strategic plan objectives for integrative biology and sustainable agriculture, including 'functional and comparative genomics', 'integrative biology-plant', 'transcriptomics', 'whole organism biology' and 'sustainable agriculture'. It will aim to provide a 'pipeline' for the delivery of information gained from studies in model species to tools for use to enhance breeding germplasm, a key recommendation of the recent BBSRC Crop Science Review.