GCRI Trust Travel Grant Report 2015
GCRI Trust Travel Grant Report 2015
ISRR9 – 9th Symposium for the International Society of Root Research
6-9 October 2015, Canberra, Australia
Dr Stefan Mairhofer
The awarded GCRI trust travel grant was received to attend the ISRR9[1] – an international symposium on root research, where a large community from around the world came together to discuss new ideas and the latest advances in the field of plant root science. Research at different scale, ranging from cellular to whole organism and systems level, addressing many active research areas, such as the environmental impact on roots through climate change and their adaptation to stresses due toresource (un-)availability, their interaction and responses to microorganisms in the soil rhizosphere, and their role in farming systems, were among the many themespresented and discussed at the symposium.
The event was opened with an inspirational reminder about the exceptional ability of plants to influence the soil through their roots, “ ...to create a prosperous environment that allows plants to thrive and to protect them from hostile conditions, while giving life back to the soil”. The advances over recent decades in sensor, measure and imaging technologies, allowed a major improvement in our understanding of root development and their interaction with a changing environment. This will continue to play an essential role for future discoveries.
Tuesday 6 October: Roots responding to climate change
The first day began with a session about the impact of global change on the biodiversity and ecosystem function, with particular focus on belowground plant and microbial communities. These changes operate on different spatial and temporal scales with consequences to the global carbon cycle. Climate change also influences root turnover. While empirical evidence suggests no systematic increase in root lifespan under elevated atmospheric carbon dioxide, it has been shown that an increase in temperature reducesoverall fine root lifespan,which leads to an increase in root turnover. High root turnover may reduce crop productivity and plant competitive effectiveness. An increased risk to plants is also the climate change induced drought. Attention has been therefore directed to deep root systems. Plants that have a deep root system recover better from more frequent and intensive drought events. While deep roots play an important role in water uptake, it is also important to understand the mechanism of how plants extract water from the root soil interface. The flow of water in soil and roots is driven by gradients in water potential. As plants take up water the soil dries, its conductivity decreases, which in turn may limit the ability of further water acquisition. Studies have revealed the importance of root exudate mucilage in the process of water uptake. Mucilage maintains the soil wet and conductive, and therefore forms a bridge between soil and roots, facilitating water flow in dry soils. Drought remains a relevant topic for future research. While deep root is a classic trait, to confer improved crop productivity across increasingly unpredictable drought-prone environments, attention to different multiple traits acting together is necessary.
(Among the highlighting speakers were: Richard Bardgett, David Eissenstat, Andrea Carminati, Amelia Henry)
Wednesday 7 October: Root hairs and functions
Root hairs have special and unique functions, among which is the uptake of nutrients with limited mobility by increasing root surface area, symbiosis with soil bacteria and facilitating the penetration of the soil. Genetic screens have identified the Root Hair Defective Six Like (RSL) gene, a gene from an ancient genetic network, that has shown to positively regulate root hair development in Arabidopsis thaliana, by controlling activities required for cell growth. The RSL gene therefore, could be useful in studies to investigate the role of root hairs in relation to nutrient uptake. Long root hairs are often associated with a wide rhizosheath formation, which has been demonstrated to have positive effects on phosphorous uptake by many crop species in low phosphorous soils. Because of their role in resource uptake, root hairs present an important target trait for breeding crops in low-input agricultural systems. Not only the absorption, but also the transport of nutrients is important for plant growth and development. In rice, the Lsi1 and Lsi2 gene expressions, located at the exodermis and endodermis of the roots, are relevant to silicon transport, which is important for high and sustainable production of rice. Studies suggest that these transporters play also a role in the uptake of arsenite in rice roots. Further efforts are required in the identification of root transporters for nutrient uptake.
(Among the highlighting speakers were: Liam Dolan, Jian Feng Ma, John Kirkegaard)
Thursday 8 October: Root architecture and nutrients
While small scale traits, such as root hairs, are relevant for theefficient uptake of certain nutrients, it is well know that also the plasticity of different root architectures play a significant role in the process of exploring the soil environment and thus the acquisition of nitrogen and phosphorous. Stresses of low nitrogen, for instance, can increase axial root elongation in maze, while reducing length and density of lateral roots. Thus roots respond differently to the presence of lack of nutrients. An impact on root architecture can also have the competition of roots for resources. This was the topic of my presentation, in the root modelling and image analysis session. Using X-ray microcomputed tomography (µCT), root systems of interacting plants can be imaged and analysed non-invasively in three dimensions. I presented different measures that can be computed from the acquired image data, to quantify and express the level of interaction and competition between root systems. Findings of this study are of particular relevance in agriculture for intercrop cultivation, with potential impact on crop productivity and resource-use efficiency, as well as resource competition between crops and weed plants, such as the threat posed by blackgrass in the UK. Further research will be conducted where developed methods are applied to combinations of different crops and/or grass plants.
(Among the highlighting speakers were: Hong Liao, Yoshiaki Inukai, Leslie Watson)
Friday 9 October: Root genetics and breeding
Soils are very heterogeneous and changing environments, in which plants seek to optimise root distribution to sometimes conflicting parameters, but that are crucial to their growth and development. The genetic and molecular basis underlying root growth regulation has been approached and many genes and pathways have been uncovered that play key roles for root growth processes.Recently there has been an increasing interest in both genetic and management strategies to improve root system function as a pathway to improved crop productivity. Critical to such endeavours is a clear understanding of how manipulation of plant root systems will influence productivity with the broader context of the crop cycle, crop sequence and farming system. Breeding for improved crop rooting is often hindered by the difficulties of studying root growth and functions in the soil. Through the combination of modern high throughput phenotyping pipelines, genome wide association studies and functional genomics, it is possible to identify genetic networks and molecular mechanisms that quantitatively regulate root growth and development in natural crop populations. This opens new opportunities for future efforts in improving root performance for cropping systems in agriculture.
(Among the highlighting speakers were: Wolfgang Busch, Jianhua Zhang)
The symposium was ended with a talk about ‘Roots for the future’. To meet the challenge of an increased demand for global food security, it is inevitable to design resource-efficient crop root systems that are able to maintain appropriate root growth and functions in stressful soils, and thus to guarantee plant survival and crop productivity in agriculture. The symposium was very informative and by attending the ISRR9, I had the opportunity to engage with international experts in the field of root research, exchange fruitful ideas and knowledge, and to build the basis for future collaborations, allowing me to be part of future developments and scientific endeavours. I am very grateful to the GCRI trust for the financial contribution towards the expenses of my conference experience.
Dr Stefan Mairhofer
School of Biosciences / Computer Science
The Centre for Plant Integrative Biology
University of Nottingham, UK
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