Understanding and exploiting a nitrogen-fixing endophyte for enhancing sustainability and productivity of vertical farming

英国40%的水果和蔬菜通过这些供应链进口，受产区天气和地缘政治问题的影响，农产品短缺在英国变得越来越普遍。以可持续的方式增加英国的产量，对于为英国的水果和蔬菜供应提供弹性至关重要。垂直农业是一个快速增长的部门，提供可靠的全年生产，以提高生产率，在非农业土地上生产，化学投入最少(化肥/杀虫剂)，没有径流污染和高效用水。垂直耕作的受控条件可以最大限度地促进生长(最大限度地减少收获时间)，并防止浪费(来自不利的气候)。然而，英国PACE园艺食品生产面临的一个关键挑战是高昂的能源成本和相关的温室气体排放。大幅增加这些作物的产量和/或减少收割天数，而不增加生产的环境负担，是确保稳定和可持续供应的唯一解决办法。我们的项目旨在提高资源利用效率-提高生产率，同时降低成本和每公斤产品的温室气体排放。氮素的可获得性是作物产量的限制因素，但化肥的使用对温室气体排放有很大影响，即使在受控制的环境农业中也是如此。在这里，我们研究了一种能够从空气中固定氮素的内生细菌，并利用这种内生细菌来提高垂直农业的资源利用效率。重氮葡萄糖乙酸杆菌最先从甘蔗中鉴定出来，能够在多种作物上定殖。它通过两个主要机制刺激植物生长：向植物细胞提供氨的固氮；以及分泌植物激素和小分子，引起根系构型的变化，从而提高养分的利用效率。显然，在甘蔗中，重氮菌可以提供植株所需的相当大比例的氮素，而且重氮菌处理可以使田间马铃薯产量增加30%。然而，我们知道不同品种的作物对重氮菌的定植和生长反应是不同的，而重氮菌定植的影响还没有在垂直耕作系统中得到测试。生菜是英国种植的最有价值的叶类蔬菜，越来越多的生产是通过控制环境农业来实现的。在这个项目中，我们将使用数量遗传学和转录组图谱来确定决定生菜定殖和/或对重氮菌反应的遗传位点和候选机制。我们将研究重氮菌对产量/采收天数的影响，内生固氮对生菜含氮量的贡献，以及固氮与根系变化的相对重要性。我们将量化在商业规模的垂直耕作系统中生长的重氮藻对生菜的影响，并确定重氮菌对垂直农场生菜生产的温室气体排放和经济效益的影响。我们的建议解决了PACE挑战中的三个领域(通过设计更好的系统来提高作物的产量、减少环境影响和实现可持续发展目标，以及可持续地提高产量、质量和生产力)。项目成果将可持续地提高垂直耕作系统的生菜产量，为整个生菜CEA供应链带来环境和经济效益。结果将推动培育和/或选择生菜品种，通过重氮菌的定植提高资源利用效率；为垂直未来客户优化种植配方和技术；以及固氮化产品的新市场。

The UK imports 40% of its fruit and vegetables with these supply chains subject to disruption through weather in production areas and geopolitical issues, with shortages of produce becoming more common in the UK. Increasing UK production in a sustainable manner is critical to provide resilience to UK fruit and vegetable supply. Vertical farming is a rapidly-growing sector offering reliable year-round production for increased productivity, production on non-agricultural land with minimal chemical inputs (fertilizer/pesticides), no run-off pollution and highly-efficient water use. The controlled conditions of vertical farming maximise growth (minimising time-to-harvest) and prevent waste (from unfavourable climate). However, a key challenge to UK production of PACE horticulture edibles is the high energy cost and associated GHG emissions. Significant increases in the yield of these crops and/or reduction in days-to-harvest, without increasing the environmental burden of production, is the only solution to ensure a stable and sustainable supply. Our project is aimed at increasing resource use efficiency - enhancing productivity whilst reducing costs and GHG emissions per kg of produce.Availability of nitrogen is a limiting factor for crop yield, but fertilizer use contributes significantly to GHG emissions, even in controlled environment agriculture. Here, we investigate an endophytic bacterium that is able to fix nitrogen from the air and exploit this endophyte to enhance resource use efficiency of vertical farming. Gluconacetobacter diazotrophicus was first identified from sugarcane and able to colonise many different crops. It stimulates plant growth via two main mechanisms; nitrogen fixation that provides ammonia to plant cells; and secretion of phytohormones and small molecules that induce changes in root system architecture, resulting in enhanced nutrient use efficiency. It is clear that in sugarcane G. diazotrophicus can provide a significant proportion of the nitrogen required by the plant and G. diazotrophicus treatment can increase potato yield by up to 30% in the field. However, we know that different varieties of crops vary in G. diazotrophicus colonisation and growth response, and the impact of G. diazotrophicus colonization has not been tested in vertical farming systems.Lettuce is the most valuable leafy vegetable grown in the UK and an increasing proportion of production is via controlled environment agriculture. In this project we will use quantitative genetics and transcriptome profiling of a lettuce diversity set to identify genetic loci and candidate mechanisms determining lettuce colonisation and/or response to G. diazotrophicus. We will investigate the impact of G. diazotrophicus on yield/days to harvest, the contribution of endophyte nitrogen-fixation to lettuce nitrogen content and the relative importance of nitrogen fixation versus root system changes. We will quantify the effects of G. diazotrophicus colonization on lettuce when grown in a commercial-scale vertical farming system and determine the impacts of G. diazotrophicus on GHG emissions and economics of lettuce production in a vertical farm.Our proposal addresses three of the PACE challenge areas (Genetic improvement of crops for increased yield, Reducing environmental impacts and progressing towards sustainability targets, and Sustainably increasing yield, quality and productivity by designing better systems). Project outcomes will sustainably enhance lettuce production in vertical farming systems with environmental and economic benefits across the lettuce CEA supply chain. Outcomes will drive breeding and/or selecting lettuce varieties for enhanced resource use efficiency via G. diazotrophicus colonisation; optimised growing recipes and technology for Vertical Future clients; and new markets for Azotic products.