Linking Root Architecture to Function:
Theory, Methods and Technology

Agricultural production systems are confronted with an array of challenges that limit resource availability needed for plant productivity: 

• Climate change is affecting average temperature and rainfall (amount and distribution) 
• Soil degradation and limits to inputs are reducing nutrient availability 
• Abiotic and biotic stresses alone and in combination are increasing – emphasis must be on maintaining productivity efficiency as opposed to simply survival under stress conditions  

In addition to these challenges, the rising world population is increasing its demand for quantity and quality of plant-based products. 

Significant research has been done on plant responses to changes in the environment, in which an important role for roots has been recognized. However, given the complexity of belowground dynamics and the logistical difficulties in adequately measuring the root system, many breakthroughs in the quantification of root systems and their functions have happened relatively recently and are ongoing using cutting edge techniques.  

One element of roots that has received increasing attention in recent years is the root system architecture. Various imaging and sampling techniques have been developed, but now the emphasis appears to be the ability to link architectural information with function – from many different scales including whole system to cellular. Effectively coupling studies of root architecture would give the most promising impact towards addressing the true role of roots in mitigating the challenges in stress and environmental perturbation. 

The central focus of this course will include an exploration of new techniques that couple studies of root system architecture and function, hands-on experience with some of these techniques, and the new approaches to delve deeper into the analysis of the resulting data, from modeling to machine learning techniques. Specific topics will include: 

Defining root structure (cellular, organ), architecture, and function –  

Arriving at a common set of definitions used throughout the course 

Methods Overview – imaging, sensing 

What are the limitations of each approach – practical vs. theoretical? Controlled conditions vs. field 

What are the scales at which particular methods are appropriate? Whole plant to cellular, molecular 

What questions are addressed most appropriately in each approach? 

What are the approaches that can most effectively integrate across structure, architecture, and function to arrive at mechanistic understanding of process?  

Resulting Data 

What sorts of data are produced in a given approach? 

What are the techniques (current and in development) available for analysing this data?  

Benefits and pitfalls of modelling – when does it hold up and when does it fail? 

Note: we will have a hands-on data set to illustrate the application of modelling vs. machine learning approaches. 

Sensing environmental impacts on function 

Microorganisms and their interactions with root systems (mycorrhizas, PGPR, rhizobia-symbiosis) 

Root-root interactions (allelopathy  

Coupling environmental sensing to infer root structure and function 

The next step – identifying adapted phenotypes 

Breeding approaches utilizing knowledge of architecture and function 

Molecular approaches 

The course is composed of a series of lectures, discussions sessions, working group activities, hands-on data analyses, excursions to a root research sites, and a final course debate of a case study. The course will be 5.5 days. 

1. Key-note / Introduction Lecture

The course starts off (Sunday afternoon after dinner) with an introduction lecture by an invited speaker to give an overview of the current state of knowledge on root biology and the challenges and opportunities that are present. 

2. Lectures and Discussion

Following each lecture (30-45 minutes), a 30-45 minutes discussion will be held.   

3. Hands-on tours and data analysis

Afternoons will include tours of ongoing root research projects at various locations and analysis of actual data sets from the projects. For data analysis, various approaches will be compared for their effectiveness in addressing specific questions focused on for the project where the data originated. Students will work in groups of 3-4 and will report their findings and critique of the methods for analysis that were utilized. What questions were answered, what were the limitations to the approach? 

4. Evening paper discussions

Current literature will be discussed each evening after dinner. Student groups (2-3 students each) will be responsible for presenting the paper for a given evening and leading a discussion about the topic. 

5. Final class debate

On the final day of the course, student groups will be presented with case studies aimed at examining root architecture and function at different scales. Two groups will be paired to address one case study. The two groups will debate the issues presented in class – feasibility of the method, appropriate scale for the questions asked, data analysis approaches, and the synthesis and impact of information gained. 

Participants must have knowledge in botany and plant physiology and some knowledge in soil chemistry