Drought, plant symbionts and silicon - improving crop water relations under future climate change scenarios

粮食安全受到干旱对作物产量不利影响的威胁。干旱的频率和严重程度都在增加，全球粮食生产很大程度上依赖于雨养农业，因此迫切需要提高作物抗旱能力的可持续方法。许多作物积累到很高水平的硅已被证明可以保护植物免受干旱胁迫。其机制尚不清楚，但一种可能是根细胞壁增强导致更好的土壤渗透、水分吸收和运输。丛枝菌根真菌（AMF）与大多数陆地植物（包括大多数农业上重要的作物物种）形成共生关系，并可能给其寄主植物带来许多好处，包括改善水分关系。它们也被证明可以增加硅的吸收。然而，在集约化耕作方式下，AMF的丰度和多样性有所下降；剩下的物种是否对硅吸收和植物水分关系有最大的有益影响是完全未知的。AMF定殖、根际微生物群落和硅供应对抗旱性的相互作用也尚未研究。该项目将利用创新的新技术来解决这一知识缺口，研究硅在植物根系中的沉积方式，这对植物水分关系和作物产量的影响，以及这一过程如何受到AMF的影响。它还将测试不同种类的AMF是否对硅吸收有不同的影响，以及AMF如何影响微生物群落的其他组成部分以及这对硅吸收的影响。成功的学生将参加一个项目，该项目在改善粮食安全和通过新的可持续方法保护作物免受气候变化的影响方面具有潜在的现实影响。他们将受益于植物生物学和生态生理学方面的培训，以及最先进的分析和成像技术，包括便携式x射线荧光光谱仪、新型稳定同位素跟踪技术和微生物群落分析。他们还将受益于与加州大学的合作，该大学将使用13c稳定同位素和纳米级成像质谱法来跟踪根际群落个体成员的碳运动。这将为干旱如何影响地下碳分配提供新的见解，土壤微生物群落的哪些组成部分从这种增加的碳中受益，以及对作物系统中营养获取动态和碳循环的影响。

Food security is threatened by the adverse effects of drought on crop yields.Droughts are increasing in both frequency and severity, and much of globalfood production relies on rain-fed agriculture, so sustainable approaches toincreasing crop resilience to drought are urgently needed. Silicon, which manycrops accumulate to high levels, has been shown to protect plants againstdrought stress. The mechanisms responsible remain unclear, but onepossibility is strengthened root cell walls leading to better soil penetration,water uptake and transport.Arbuscular mycorrhizal fungi (AMF) form a symbiotic relationship with themajority of land plants including most agriculturally important crop species, andmay confer a number of benefits to their host plant, including improved waterrelations. They have also been shown to increase silicon uptake. However, theabundance and diversity of AMF has declined under intensive farming methods;if the remaining species are the ones which have the greatest beneficialimpacts on silicon uptake and plant water relations is completely unknown. Theinteracting effects of AMF colonisation, rhizosphere microbial community andsilicon supply on resistance to drought stress have also not yet been studied.This project would address this knowledge gap using innovative newtechniques to study the way silicon is deposited in plant roots, the effect thishas on plant water relations and crop yields, and how this process is affected bythe presence of AMF. It will also test whether different species of AMF affectsilicon uptake differently, and how AMF influence other components of themicrobial community and the effect of this on Si uptake.The successful student will join a project with the potential for real worldimpact in terms of improved food security and protecting crops from theeffects of climate change through novel sustainable approaches. They willbenefit from training in plant biology and ecophysiology, as well as state-of-the-art analytical and imaging techniques, including portable X-ray florescencespectroscopy, novel stable isotope tracking techniques and microbialcommunity analysis. They will also benefit from collaboration with University ofCalifornia which will use 13Carbon stable isotopes and Nano-Scale Imaging MassSpectrometry to track carbon movement through the individual members ofthe rhizosphere community. This will provide novel insights into how droughtaffects carbon allocation below ground, which components of the soil microbialcommunity benefit from this increased carbon and the implications for nutrientacquisition dynamics and carbon cycling in crop systems.