Investigating resistance to Barley yellow dwarf virus in wheat

大麦黄矮病毒(BYDV)威胁着英国小麦的可持续生产。BYDV的控制历来依赖于以杀虫剂为基础的媒介定向缓解策略，清除在取食过程中获得和传播病毒的蚜虫物种。在2018年底禁令生效之前，新烟碱类种子处理被广泛用于保护冬小麦。种植者保留了使用拟除虫菊酯等替代杀虫剂的选择，但这些杀虫剂需要叶面喷洒，这种喷洒在秋季条件下既不总是可能，也不特定，杀死有益的昆虫。关键种类的蚜虫对拟除虫菊酯的抗性水平也在增加。再加上对拟除虫菊酯的需求，杀虫剂耐药性迅速传播的风险非常高，进一步减少了可用于控制黄矮病病毒的化学武器库。因此，遗传抗性的来源是有价值的，并已成为小麦育种者重新关注的焦点。这包括最近开发出抗黄矮病病毒的品种RGT Wolverine的RAGT Seed。这个PHD项目将包括筛选狼獾对BYDV信息丰富的分离株的抗性(和/或耐受性)来源，鉴定对不同病毒株的抗性水平，并确定株系互补是否可以克服耐药性。通过一系列的实验，包括基于抗体的全植物组织打印和Western blotting，还将探索BYDV在抗性和感病植物品系中的时空移动。利用‘MutChromSeq’方法，或转录组学和批量分离分析相结合的方法，将阐明支撑BYDV抗性的原因基因组座位。与这项工作相一致，另一个重点将是开发一种针对黄矮病病毒的中高通量RT-qPCR检测方法，以及帮助识别和/或验证其他耐药性的新方法和技术。目前存在有限的可靠的现场BYDV抗性筛选方法，大多数测试依赖于自然的BYDV存在。在这次PHD期间，BYDV的流行毒株将被鉴定(通过Rothamsted UK昆虫吸引器网络)，并用于开发感染性克隆(IC)。将探索这些IC与生物接种策略的使用，并可能开发一种IC‘工具包’来筛选小麦种质。这将简化细菌培养中BYDV纯毒株的维护，快速生成所需的接种物，并对BYDV毒株互补进行强有力的调查。这一博士学位提供了一个产生有价值的应用成果的机会，提供了(如果需要)关于分子生物学/病毒学技术、生物信息学、昆虫学、批判性思维和概念化、数据解释以及温室和实地工作的培训。

Barley yellow dwarf virus (BYDV) threatens sustainable UK wheat production. Control of BYDV has historically relied upon vector-targeted mitigation strategies underpinned by pesticides, removing aphid species which acquire and spread the virus during feeding. Prior to late 2018 when a ban came into force, neonicotinoid seed treatments were widely used to protect winter wheat. Growers retain the option of alternative insecticide use, such as pyrethroids, but these require foliar sprays which are neither always possible in autumnal conditions nor specific, killing beneficial insects. Increasing levels of pyrethroid resistance by key aphid species are also being recorded. Combined with the demand for pyrethroids, a markedly high risk for rapid spread of insecticide resistance exists, further reducing the chemical arsenal available for controlling BYDV. Sources of genetic resistance are consequently of value and have become a renewed focus by the wheat breeders. This includes RAGT Seeds who have recently developed the BYDV resistant cultivar RGT Wolverine. This PhD project would involve screening the Wolverine source of BYDV resistance (and/or tolerance) against informative BYDV isolates, qualifying the level of resistance to different virus strains and determining whether strain complementation could overcome resistance. Through a series of experiments including antibody-based whole plant tissue printing combined with western blotting, the spatial and temporal movement of BYDV within resistant and susceptible plant lines will also be explored. Using the 'MutChromSeq' approach, or transcriptomics combined with bulk segregant analysis, the causal genomic loci underpinning the BYDV resistance will be elucidated. In concert to this work, an additional focus will be the development of a mid/high-throughput RT-qPCR assay for BYDV, as well as new approaches and technologies to help identify and/or validate other resistances. Limited reliable in-field BYDV resistance screening methodologies currently exist with most testing relying upon natural BYDV presence. During this PhD, prevalent strains of BYDV will be identified (via the Rothamsted UK insect suction trap network) and used to develop infectious clones (ICs). The use of these ICs with biolistic inoculation strategies will be explored and an IC 'toolkit' for screening wheat germplasm potentially developed. This would allow simplified maintenance of pure BYDV strains in bacterial cultures, rapid generation of a desired inoculum and robust investigations into BYDV strain complementation. This PhD represents an opportunity to generate valuable applied outputs with training provided (where required) on molecular biology/virology techniques, bioinformatics, entomology, critical thinking and conceptualising, data interpretation, and glasshouse and field work.