Mutant-assisted exploration of natural variation underlying R gene-mediated immunity in maize

PI: Gurmukh (Guri) S. Johal，普渡大学合作PI: Clifford F. Weil，普渡大学合作PI: James。植物抗病(R)基因编码的蛋白质通过触发快速的、局部的“超敏反应”（HR）来应对病原体的入侵，在这种反应中，紧邻感染部位的宿主组织经历程序性细胞死亡。虽然，HR是植物免疫反应的基本组成部分，但我们对触发、发出信号、执行和控制它的基因知之甚少。在拟南芥中进行了详尽的突变筛选，但只发现了少数与HR相关的基因，可能是由于基因冗余或HR突变体的致命性。在自然种质资源中存在着另一种潜在的巨大的HR变异资源。如果有效地挖掘和描述，这一资源有可能大大提高我们对人力资源的理解。通过利用Rp1基因的组成型活性等位基因，我们已经证明玉米种质含有大量能够影响HR的变异。Rp1基因赋予玉米对常见锈病的抗性。该项目将测试一种创新方法的广泛应用，该方法寻找抑制突变表型的自然存在的等位基因，以快速检测和探索HR背后的自然变异。使用这种方法，一个hr调节位点（Hrml1）已经在使用IBM玉米群体的初步测试中被识别和定位；这个QTL将被克隆。此外，通过将筛选范围扩大到玉米群落现有的5000系嵌套关联图谱（NAM）群体，将鉴定和表征更多的QTL。该项目的广泛影响是多方面的。首先，发现和利用遗传多样性的方法可能广泛适用于大多数植物物种的大量重要性状。其次，拓展部分将生物多样性的应用引入中学课程（6-8年级），将DNA序列分析和数量性状分析的主题引入高中课程，并开发和测试可广泛分发的教材。第三，这些教学模块将为来自不同文化、种族和教育背景的学生及其教师开发。这种方法将允许开发这些模块的几个版本，使用不同的例子、不同的评估和不同的呈现形式，以便它们可以在各种环境中有效地应用。我们的目标是推翻那些认为这些学科过于复杂，初高中学生无法掌握的刻板印象，并引导学生在以后的教育中更详细地研究植物多样性和遗传学，以便他们能够更好地理解这些问题。尽管这些主题在科学和社会上的重要性日益增加，但在这些级别的大多数科学课程中通常没有涉及这些主题。该项目的成果和生物资源将通过该项目的网站：http://www.Rp1-MAGIC.purdue.edu提供。

PI: Gurmukh (Guri) S. Johal, Purdue UniversityCo-PI: Clifford F. Weil, Purdue UniversityCo-PI: James. W. Moyer, North Carolina State UniversityCo-PI: Peter J. Balint-Kurti, North Carolina State UniversityPlant disease resistance (R) genes encode proteins that respond to pathogen invasion by triggering a rapid, localized "hypersensitive reaction" (HR), in which host tissue immediately adjacent to the site of infection undergoes programmed cell death. Although, HR is a fundamental part of the immune response in plants, very little is known about the genes that trigger, signal, execute, and then contain it. Exhaustive mutagenesis screens have been conducted in Arabidopsis, but have turned up only a few genes linked to HR, possibly because of genetic redundancy or lethality of HR mutants. An alternate and potentially huge resource of HR variation is available in natural germplasm. If effectively tapped and delineated, this resource has the potential to advance considerably our understanding of HR . By taking advantage of a constitutive-active allele of the Rp1 gene, which confers resistance to the common rust disease of maize, we have demonstrated that the maize germplasm contains vast amounts of variation capable of impacting HR. This project will test the broad use of an innovative approach, which looks for naturally occurring alleles that suppress mutant phenotypes to rapidly detect and explore natural variation underlying HR. Using this approach, one HR-modulating locus (Hrml1) has already been identified and mapped in a preliminary test using the IBM population of maize; this QTL will be cloned. In addition, many more QTL will be identified and characterized by broadening the screen to the 5000-line Nested Association Mapping (NAM) population currently available to the maize community. The broader impacts of the project are many-fold. First, the approach of discovering and harnessing genetic diversity is likely to be broadly applicable to a large number of important traits in most plant species. Second, an outreach component will bring the uses of biodiversity to middle school curricula (Grades 6-8) and the topics of DNA sequence analysis and quantitative trait analysis to high school curricula, with the development and test of teaching materials that can be widely distributed. Third, these teaching modules will be developed for and with students from a wide range of cultural, racial and educational backgrounds, and their teachers. This approach will allow development of several versions of these modules, using different examples, different assessments and different forms of presentation so that they can be applied effectively in a variety of settings. The goal is to overturn the stereotype that these subjects are too complex for middle and high school students to grasp, and to prime student to investigate plant diversity and genetics in greater detail later in their education so that they are better able to understand the issues. These topics are not generally covered in most science curricula at these levels, despite their increasing importance scientifically and socially. The outcomes and biological resources generated by this project will be available through the project website: http://www.Rp1-MAGIC.purdue.edu.