The role of calcium signaling in Arabidopsis thaliana for haustoria development by the oomyceteHyaloperonospora arabidopsidis

在被子植物中，一种古老的根共生遗传程序被保留下来，允许在丛枝菌根（AM）共生期间在细胞内调节营养传递真菌。AM的起源可以追溯到最早的陆地植物，只有像芸苔科这样的特殊植物谱系最近才失去了AM的共生关系，这与拟南芥基因组中大量共生特异性基因的缺失有关。然而，在拟南芥中仍然存在诸如污染性共生基因之类的残留基因。在豆科植物中，与共生相关的核钙振荡（钙峰值）需要一个阳离子通道，因此被认为是核钙峰值机制的重要组成部分。尽管在不同的实验室进行了详细的分析，但拟南芥的污染突变体缺乏任何可识别的表型，因此其作用和进化力量导致其在基因组中的特定功能保留尚不清楚。豆科污染突变体在真菌和细菌共生体的细胞内调节方面受损。我们最近发现，在拟南芥中，poloxx是拟南芥透明operonospora Arabidopsis的完全繁殖成功和吸器（这种生物营养性卵菌的细胞内感染结构）的发育或维持所必需的。这一令人兴奋的发现揭示了以前怀疑的，但从未真正检测到的宿主程序之间的遗传共性，以发展或维持共生和致病性感染结构。我们建议研究拟南芥中钙信号在卵菌吸器发育中的作用，这可能是由POLLUX的参与所暗示的。我们的目标是通过与FOR964的中央钙成像平台合作，澄清在感染期间产生（核）钙信号的污染性预测作用。此外，我们将评估候选钙信号解码器与吸器发育和卵菌感染期间宿主转录重编程的相关性。预期的结果将有助于进一步剖析参与核钙信号解码的遗传程序。对pollux特异性转录变化的分析可能有助于解答一个令人困惑的问题，即为什么拟南芥维持一个没有可检测作用但能提高病原体性能的基因。

An ancient genetic program for root symbiosis is conserved among angiosperms to allow intracellular accommodation of nutrient-delivering fungi during the arbuscular mycorrhiza (AM) symbiosis. The origin of AM dates back to the earliest land plants and only exceptional plant lineages like the Brassicaceae have lost the AM symbiosis more recently, which correlates with the specific absence of a large cohort of symbiosis-specific genes in the Arabidopsis genome. However, vestigial symbiosis genes such as POLLUX are still present in Arabidopsis. POLLUX encodes a cation channel that in legumes is required for symbiosis-associated nuclear calcium oscillations (calcium-spiking) and is thus considered an essential component of the nuclear calcium-spiking machinery. Despite detailed analysis in different laboratories, pollux mutants of Arabidopsis lacked any discernable phenotypes so its role and the evolutionary forces leading to its specific functional retention in the genome was obscure. Legume pollux mutants are impaired in intracellular accommodation of fungal and bacterial symbionts. We recently discovered that in Arabidopsis, POLLUX is required for full reproductive success of Hyaloperonospora arabidopsidis and the development or maintenance of haustoria, the intracellular infection structures of this biotrophic oomycete. This exciting finding reveals previously suspected, but never actually detected, genetic commonalities between the host programs for the development or maintenance of symbiotic and pathogenic infection structures. We propose to investigate the role of calcium signatures in Arabidopsis for oomycetal haustoria development, which is implied by the involvement of POLLUX. We aim to clarify the predicted role of POLLUX in generating (nuclear) calcium signatures during infection in collaboration with the central calcium-imaging platform of FOR964. Furthermore, we will assess the relevance of candidate decoders of calcium signatures for haustorium development and the transcriptional reprogramming of the host during oomycetal infection. The expected results will help to further dissect the genetic program involved in the decoding of nuclear calcium signals. The analysis of POLLUX-specific transcriptional changes may help to provide answers to the puzzling question why Arabidopsis maintains a gene that has no detectable role but to improve the performance of a pathogen.