Discovery of a symbiotic signalling mechanism from maize.

共生是地球上生命的基础。其中一个例子，被称为丛枝菌根（AM）共生，在真菌和植物之间进化，以促进从土壤中吸收矿物质。这种共生安排是如此广泛，以至于它影响了生态系统的生产力，并被认为对作物生产力和可持续性至关重要。因此，对支持AM共生发展和功能的过程的理解在整个植物界具有普遍意义。功能共生关系的建立依赖于信号的精细编排，以实现相互作用的植物和AM真菌的协调。突变植物的鉴定和分析已经形成了我们对支持种间串扰的分子机制的理解的基础，这种机制允许这种共生。根际植物和AM真菌的相互识别是共生结果的核心，目前知之甚少。Paszkowski实验室此前从谷物中发现了控制共生前识别的关键基因[Gutjahr等人（2015）Science 350:1521；纳达尔等（2017）Nature Plants 3:17073]，最近，已经鉴定出独立于丛枝菌根（ina）的玉米突变体。玉米ina植株显示出对AM真菌完全丧失敏感性，但是可以通过添加野生型而不是突变体的根分泌物来补充。这是一种以前未被描述过的独特表型，表明INA是玉米共生前信号传导不可或缺的新途径的一部分。定位克隆表明，缺失的三个候选基因与突变表型共分离。为了发现INA基因的特性，目前正在生产其他CRISPR/ cas9编辑的玉米等位基因，并将于2020年底上市。这项为期18个月的资助的目的是使用新的玉米突变体材料来发现INA基因身份，采用我们的标准表型方案。此外，它试图通过确定INA无法与AM真菌结合的转录组基础，首次深入了解INA所起的作用。了解INA基因的性质将指导未来的研究方向，并为发现地球上最普遍的植物共生的新交流策略铺平道路。

Symbioses are fundamental to life on the Earth. One such example, known as arbuscular mycorrhizal (AM) symbiosis, evolved between fungi and plants to facilitate mineral uptake from the soil around 450 mya. This symbiotic arrangement is so widespread that it impacts on ecosystem productivity, and is considered of fundamental importance for crop productivity and sustainability. Generating understanding of the processes that underpin AM symbiosis development and functioning are thus of universal relevance across the plant kingdom. The establishment of functional symbioses relies on the fine-tuned orchestration of signals to achieve coordination of the interacting plant and AM fungus. Identification and analysis of mutant plants have formed the bedrock of our understanding of the molecular mechanisms that underpin the interspecies crosstalk allowing this symbiosis. Reciprocal recognition and plant and AM fungi in the rhizosphere are central to the outcome of the symbiosis and presently poorly understood. The Paszkowski lab has previously discovered key genes from cereals that condition pre-symbiotic recognition [Gutjahr et al. (2015) Science 350:1521; Nadal et al. (2017) Nature Plants 3:17073] and most recently, has identified the independent of arbuscular mycorrhiza (ina) maize mutant. Maize ina plants show a complete loss of susceptibility to AM fungi, which can however be complemented by the addition of wild-type but not ina mutant root exudates. This is a unique phenotype that has not been described before, suggesting that INA is part of a new pathway, indispensable for pre-symbiotic signalling in maize.Positional cloning revealed that a deletion with three candidate genes co-segregated with the mutant phenotype. To discover the INA gene identity additional CRISPR/Cas9-edited maize alleles are presently produced and will be available at the end of 2020. It is the aim of this 18 months grant to use the new maize mutant material to discover the INA gene identity, employing our standard phenotyping protocols. In addition it seeks to provide a first insight into the role INA plays by determining the transcriptome underpinning of the inability of ina to engage with AM fungi.Knowledge of the nature of the INA gene will guide future research directions and will pave the way to discover a novel communication strategy for the most prevalent plant symbiosis on Earth.