Shifts in plant gene expression and corresponding phloem sap components during trilateral interaction of barley (Hordeum vulgare), aphid species (Rhopalosiphum padi) and the aphid-transmitted Barley Yellow Dwarf Virus (BYDV)

蚜虫传播的大麦黄矮病毒（BYDV）以及蚜虫与BYDV的相互作用都得到了很好的描述。蚜虫-寄主和BYDV-寄主在这种三方关系中的相互作用应该进行研究，然后才能制定成功的对抗BYDV的策略。本研究的重点是韧皮部：(1)蚜虫完全以韧皮部为食；(2)BYDV的传播和运输仅限于韧皮部；(3)对侵染和感染的全身反应可能通过筛管转运。从逻辑上讲，大麦抗蚜虫侵害和BYDV感染的基因是在韧皮部表达的，它们的一些产物通过筛管转运。基因和蛋白表达谱被设想用于检测抗蚜虫和抗bydv大麦品种的局部和全身反应。为此，将采用叶组织的微阵列杂交和韧皮部分泌物的RNA和蛋白质分析来确定基因和蛋白质表达水平的变化。一旦候选基因和蛋白被确定，参与局部调控的基因的表达就会开始。系统反应将通过定量Real-Time-PCR进行研究。随后，将比较局部和全身部位（韧皮部薄壁组织、伴生细胞、筛元）的表达。最后，研究人员将绘制抗bydv候选基因图谱，以检测与已知的与bydv耐受性相关的遗传位点（QTL）的共定位。预期，这项研究将更好地了解宿主对蚜虫侵染和蚜虫传播的BYDV感染的反应，特别是关于耐受性和易感性宿主基因型的韧皮部易位信号。

The aphid-transmitted barley yellow dwarf (BYDV) luteovirus as well as the aphid-BYDV-interaction are both well described. The aphid-host and BYDV-host interactions in this tripartite relationship should be investigated before successful strategies against BYDV can be developed. The focus of this research is on the phloem: (1) aphids exclusively feed on the phloem, (2) BYDV propagation and transport is limited to the phloem, and (3) systemic responses to infestation and infection may be translocated via the sieve tubes. Logically, genes involved in barley tolerance against aphid infestation and BYDV infection are expressed in the phloem and some of their products translocated via sieve tubes. Gene and protein expression profiling are envisaged to detect local and systemic responses of aphid- and BYDV-tolerant barley cultivars. For that purpose, microarray hybridisation of leaf tissues and RNA and protein analysis of phloem exudates will be employed to identify shifts in gene and protein expression levels. Once candidate genes and proteins will have been identified, expression of the genes engaged in local resp. systemic response will be investigated by quantitative Real-Time-PCR. Subsequently, expression in local and systemic sites (phloem parenchyma, companion cells, sieve elements) will be compared. Finally, candidate genes for BYDV-tolerance will be mapped to detect co-localisation with known genetic loci (QTL) related to BYDV-tolerance. Expectedly, this study will provide a better understanding of the host response to aphid-infestation and infection by aphid-transmitted BYDV, in particular, with regard to the phloem-translocated signals of tolerant vs. susceptible host genotypes.