bettina berger

Growing rice faster – uncovering the triggers behind early canopy closure

By combining high-resolution image-based phenotyping with functional mapping and genome prediction, a new study has provided insights into the complex genetic architecture and molecular mechanisms underlying early shoot growth dynamics in rice.

The more rapidly leaves of a plant emerge and create canopy closure, the more successful the plant, in establishment, resource acquisition and ultimately yield. An early vigor trait is particularly important in aerobic rice environments, which are highly susceptible to water deficits. The timing of developmental ‘triggers’ or switches that initiate tiller formation and rapid exponential growth are a critical component of this trait, however, searching for the switch that initiates this growth has proven challenging due to the complex genetic basis and large genotype-by-environment effect, and the difficulty in accurately measuring shoot growth for large populations.

“The availability of large, automated phenotyping platforms, such as those at Australian Plant Phenomics Facility (APPF), allow plants to be non-destructively phenotyped throughout the lifecycle in a controlled environment, and provide high resolution temporal data that can be used to examine these important developmental switches,” said PhD student, Malachy Campbell.

Malachy and team, including Bettina Berger and Chris Brien from the APPF, phenotyped a panel of ~360 diverse rice accessions throughout the vegetative stage (11-44 day old plants) at The Plant Accelerator® at APPF. A mathematical equation was used to describe temporal growth trajectories of each accession. Regions of the genome that may regulate early vigor were inferred using genome-wide association (GWA) mapping. However, many loci with small effects on shoot growth trajectories were identified, indicating that many genes contribute to this trait. GWA, together with RNA sequencing identified a gibberellic acid (GA) catabolic gene, OsGA2ox7, which could be influencing GA levels to regulate vigor in the early tillering stage.

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Dr Malachy Campell in The Plant Accelerator® at the Australian Plant Phenomics Facility’s Adelaide node

For some traits where genetic variation is controlled by a small number of loci, breeders can use MAS to identify individuals carrying the favourable locus/loci for the given trait, and select them for the next generation. For complex traits that are regulated by many loci, it becomes very difficult to detect loci that are associated with the trait. However, an alternative approach, genomic selection (GS), considers the total genetic contribution of all loci to the given trait. With this approach, loci across the genome can be used to predict the performance of individuals that have not yet been phenotyped (i.e. those in future generations). Since many loci were found to be contributing to early vigor, the team explored the possibility of using GS for improving this trait. Shoot growth trajectories could be predicted with reasonable accuracy, with greater accuracies being achieved when a higher number of markers were used. These results suggest that GS may be an effective strategy for improving shoot growth dynamics during the vegetative growth stage in rice. The approach of combining high-resolution image-based phenotyping, functional mapping and genome prediction could be widely applicable for complex traits across numerous crop species.

Read the full paper, published in The Plant Genome, here. (doi:10.3835/plantgenome2016.07.0064).

A step closer to salt tolerant chickpea crops

A recent study has collected phenotypic data of chickpea (Cicer arietinum L.) which can now be linked with the genotypic data of these lines. This will enable genome-wide association mapping with the aim of identifying loci that underlie salinity tolerance – an important step in developing salt tolerant chickpeas.

In this study, Judith Atieno and co-authors utilised image-based phenotyping at the Australian Plant Phenomics Facility to study genetic variation in chickpea for salinity tolerance in 245 diverse accessions (a diversity collection, known as the Chickpea Reference Set).

Chickpea is an important legume crop, used as a highly nutritious food source and grown in rotation with cereal crops to fix nitrogen in the soil or to act as a disease break. However, despite its sensitivity to salt, chickpea is generally grown in semi-arid regions which can be prone to soil salinity. This results in an estimated global annual chickpea yield loss of between 8–10%.

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Salinity tolerance phenotyping in a Smarthouse at the Australian Plant Phenomics Facility’s Adelaide node at the Waite Research Precinct – Plants were imaged at 28 DAS for 3 consecutive days prior to 40 mM NaCl application in two increments over 2 days. Plants were daily imaged until 56 DAS. Right pane shows 6-week-old chickpeas on conveyor belts leaving the imaging hall proceeding to an automatic weighing and watering station.

 

The study found, on average, salinity reduced plant growth rate (obtained from tracking leaf expansion through time) by 20%, plant height by 15% and shoot biomass by 28%. Additionally, salinity induced pod abortion and inhibited pod filling, which consequently reduced seed number and seed yield by 16% and 32%, respectively. Importantly, moderate to strong correlation was observed for different traits measured between glasshouse and two field sites indicating that the glasshouse assays are relevant to field performance. Using image-based phenotyping, we measured plant growth rate under salinity and subsequently elucidated the role of shoot ion independent stress (resulting from hydraulic resistance and osmotic stress) in chickpea. Broad genetic variation for salinity tolerance was observed in the diversity panel with seed number being the major determinant for salinity tolerance measured as yield. The study proposes seed number as a selection trait in breeding salt tolerant chickpea cultivars.

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Genotypic variation for salinity tolerance in the Chickpea Reference Set. Varying levels of salinity tolerance exhibited by different chickpea genotypes. Exposure of sensitive genotypes to 40 mM NaCl caused severe stunted growth, leaf damage, and led to less number of reproductive sites (flowers and pods) compared to moderately tolerant and tolerant genotypes.

 

The rapid development of new, high-resolution and high-throughput phenotyping technologies in plant science has provided the opportunity to more deeply explore genetic variation for salinity tolerance in crop species and identify traits that are potentially novel and relevant to yield improvement. The Australian Plant Phenomics Facility provides state-of-the-art phenotyping and analytical tools and expertise in controlled environments and in the field to help academic and commercial plant scientists understand and relate the performance of plants to their genetic make-up. A dedicated cross-disciplinary team of experts provides consultation on project design and high quality support.

To read the full paper in Scientific Reports, “Exploring genetic variation for salinity tolerance in chickpea using image-based phenotyping” (doi:10.1038/s41598-017-01211-7), click here.

To find out more about the Australian Plant Phenomics Facility and how we can support your research click here.

 

 

 

Taking the kinks out of curves

In a recent paper, researchers have developed a methodology suitable for analyzing the growth curves of a large number of plants from multiple families. The corrected curves accurately account for the spatial and temporal variations among plants that are inherent to high-throughput experiments.

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An example of curve registration.  a The salinity sensitivity (SS) curves of the 16 functions from an arbitrary family, b SS curves after the curve registration, and c the corresponding time-warping functions. The salinity sensitivity on the y-axis of a and b refers to the derivative of the relative decrease in plant biomass

 

Advanced high-throughput technologies and equipment allow the collection of large and reliable data sets related to plant growth. These data sets allow us to explore salt tolerance in plants with sophisticated statistical tools.

As agricultural soils become more saline, analysis of salinity tolerance in plants is necessary for our understanding of plant growth and crop productivity under saline conditions. Generally, high salinity has a negative effect on plant growth, causing decreases in productivity.  The response of plants to soil salinity is dynamic, therefore requiring the analysis of growth over time to identify lines with beneficial traits.

In this paper the researchers, led by KAUST and including Dr Bettina Berger and Dr Chris Brien from the Australian Plant Phenomics Facility (APPF), use a functional data analysis approach to study the effects of salinity on growth patterns of barley grown in the high-throughput phenotyping platform at the APPF. The method presented is suitable to reduce the noise in large-scale data sets and thereby increases the precision with which salinity tolerance can be measured.

Read the full paper, “Growth curve registration for evaluating salinity tolerance in barley” (DOI: 10.1186/s13007-017-0165-7) here.

Find out how the Australian Plant Phenomics Facility can support your plant science research here.

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High-throughput phenotyping in the Smarthouse™ at the Adelaide node of the APPF

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Barley plants growing in the Smarthouse™

 

 

A better way to tackle environmental variation in your greenhouse research

Statistics prove the smart way to deal with variation in your controlled environment greenhouse.

Plant phenomics allows the measurement of plant growth with unprecedented precision. As a result, the question of how to account for the influence of environmental variation across the greenhouse has gained attention.

Controlled environment greenhouses offer plant scientists the ability to better understand the genetic elements of specific plant traits by reducing the environmental variances in the interaction between genetics and environment.

But controlled environments aren’t as controlled as they seem – variation does exist. For example, some days are cloudy, some are not. The sun, as it crosses the sky, casts shadows differently on plants, depending on their position within the greenhouse. In fact, a recent study by colleagues at INRA in Montpellier showed significant light gradients within a greenhouse and provided sophisticated tools for understanding how much light each plant receives.

One practice for dealing with variation has been to rearrange the position of the plants around the greenhouse during the experiment, however, there is a better way.

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Rice plants growing in The Plant Accelerator® at the Australian Plant Phenomics Facility’s Adelaide node

The automated high-throughput phenotyping greenhouses at The Plant Accelerator® are controlled environment facilities which use sensor networks to identify and quantify environmental gradients (light, temperature, humidity) in the greenhouses. To further tackle environmental variation, Chris Brien, Senior Statistician at The Plant Accelerator®, led a study that showed good statistical design and analysis was key to accounting for the impact of environmental gradients on plant growth. It was argued that rearranging the plants during the experiment makes it impossible to adjust for the effect of gradients and should be avoided.

The study involved a two-phase wheat experiment involving four tactics in a conventional greenhouse and a controlled environment greenhouse at The Plant Accelerator® to investigate these issues by measuring the effect of the variation on plant growth.

To learn more about Chris’s study read the full paper here.

To discuss the benefits of good statistical design contact Chris Brien.

To access The Plant Accelerator® for your research:  The Plant Accelerator® at the Australian Plant Phenomics Facility (APPF) is available to all publicly or commercially funded researchers. We have a full team of specialists including statisticians, horticulturalists and plant scientists who can provide expert advice to you when preparing your research plans.

 

 

Delicious potential: The genome of quinoa decoded

Scientists have successfully decoded the genome of quinoa, one of the world’s most nutritious and resilient crops.

The study, published online this week in Nature, was an international collaboration led by Professor Mark Tester at the King Abdullah University of Science and Technology (KAUST), Saudi Arabia.

The enormously popular “super-food” is gluten-free, has a low glycaemic index and contains an excellent balance of essential amino acids, fibre, lipids, carbohydrates, vitamins, and minerals, causing international demand for the grain to soar and prices to skyrocket as demand exceeds supply.

“Apart from its nutritional benefits, the ability of quinoa to grow on marginal land is possibly most exciting”, said Prof Mark Tester. “It can grow in poor soils, salty soils and at high altitudes. It really is a very tough plant. Quinoa could provide a healthy, nutritious food source for the world using land and water that currently cannot be used, and our new genome takes us one step closer to that goal.”

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Quinoa pilot trials in the Australian Plant Phenomics Facility’s high-throughput phenotyping Smarthouse at The Plant Accelerator®

Future research projects will focus on identifying the genes that make quinoa so tolerant to poor soils. In pilot experiments carried out at the Australian Plant Phenomics Facility‘s Adelaide node, The Plant Accelerator®, different growth conditions and salt applications were tested in preparation for larger-scale studies. The first studies showed that quinoa still grows well when watered with half-strength sea water, when many other crops would die. Since performing these initial experiments, Professor Tester and his team have secured further research funding to work towards establishing quinoa as a broadacre crop.

“We are extremely excited to support this important research”, said Dr Bettina Berger, Scientific Director at The Plant Accelerator®. “As part of this collaborative project, The Plant Accelerator® will perform two screening runs of a diversity panel in the second half of 2017 to identify the genetic basis of salt tolerance in quinoa”.

Further reading:

The full published study in Nature. doi:10.1038/nature21370

KAUST An Integrated Repository for Population Genomics in genus Chenopodium

BBC News online article

Nature Middle East online article

 

What the experts are saying about plant phenotyping and food security

‘It takes a village to raise a child’ states the age-old saying, but now it will take a village to feed the child as well – if we’re smart.

“Agriculture’s critical challenges of providing food security and better nutrition in the face of climate change can only be met through global communities that share knowledge and outputs; looking inward will not lead to results,” said Ulrich Schurr, Director of the Institute of Bio- and Geosciences of the Forschungszentrum Jülich and Chair of the International Plant Phenotyping Network (IPPN), speaking at the 4th International Plant Phenotyping Symposium in Mexico recently.

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Dr Jose Jimenez-Berni (keynote speaker), Dr Xavier Sirault (Co-Chair IPPN), Dr Trevor Garnett and Dr Bettina Berger from the Australian Plant Phenomics Facility at the symposium

200 world-class scientists from over 20 countries gathered from 13 to 15 December 2016 to share knowledge and technology at the symposium, co-hosted by IPPN and the Mexico-based International Maize and Wheat Improvement Center, known by its Spanish acronym, CIMMYT.

The symposium was attended by Dr Bettina Berger, Dr Trevor Garnett, Dr Xavier Sirault and Dr Jose Jimenez-Berni from the Australian Plant Phenomics Facility (APPF). Dr Sirault is also Co-Chair of the IPPN and Dr Jimenez-Berni gave a keynote lecture on field phenotyping techniques developed at the High Resolution Plant Phenomics Facility (HRPPC) node of the APPF and how they can be applied to screen for plant development including biomass and canopy architecture in the field.

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Dr Jimenez-Berni (APPF) delivering his keynote lecture at the symposium

The symposium focused on three themes:

  • Advances in Plant Phenotyping Technologies to explore the frontiers of what can be sensed remotely and other technological breakthroughs.
  • Phenotyping for Crop Improvement to consider the application of phenotyping technologies for crop improvement (breeding, crop husbandry, and estimating the productivity of agro-ecosystems).
  • Adding Value to Phenotypic Data to review how phenomics and genomics can combine to improve crop simulation models and breeding methodologies (e.g., genomic selection).

Read the full article ‘Harnessing medical technology and global partnerships to drive gains in food crop productivity’ written by Mike Listman on CIMMYT’s website.

Read more excellent plant science articles by Mike Listman here.

 

 

Salt tolerant genetic loci in rice exposed

Rice is a staple food for over half of the world’s population. It is also the most salt-sensitive cereal crop, with losses in yield reaching up to 69%.

In a new study published in Nature Communications collaborators from King Abdullah University of Science and Technology (KAUST) and The Plant Accelerator®, Australian Plant Phenomics Facility investigated the early responses of rice plants to moderately-saline conditions and pinpointed new salt-tolerant genetic loci.

Project lead, Professor Mark Tester (KAUST), supervised PhD student Nadia Al-Tamini’s project which grew 297 indica and 256 aus rice varieties under low and high salinity. Using a technique called ‘high-throughput non-invasive phenotyping’ plants are moved on conveyor belts, imaged daily using digital cameras to monitor biomass and shoot development, and weighed to carefully measure transpiration levels (water use).

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Dr Bettina Berger (left) and Nadia Al-Tamimi (right) in The Plant Accelerator®

“The Plant Accelerator® allowed us to analyse numerous aspects of the growth of multiple plants simultaneously,” says Professor Tester.

Using the facility’s cutting-edge technology, the researchers were able to show some genes, for example those connected with signaling processes, were important to plant growth in the first two to six days after salt application, while other genes became prominent later.

“This is perhaps the most astonishing aspect of this work – we can now obtain genetic details daily, pinpointing exactly when each locus comes into play in response to salinity,” says Professor Tester.

The results of this study could prove useful for breeding programs seeking to address yield and stress resistance to meet the demand of our increasing global population and climate challenges.

Congratulations to everyone involved in this study!!

Find the full articlewww.nature.com/articles/ncomms13342

More on Nadia Al-Tamini’s story:  https://blog.plantphenomics.org.au/2015/02/24/saudi-arabian-students-joins-plant-accelerator-team-to-investigate-salinity-tolerance-in-rice/

Professor Mark Tester, Plant Science Associate Director of the Center for Desert Agriculture Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Saudi Arabia, mark.tester@kaust.edu.sa, www.kaust.edu.sa/en/study/faculty/mark-tester

Dr Bettina Berger, Scientific Director, The Plant Accelerator, Australian Plant Phenomics Facility, University of Adelaide, www.plantphenomics.org.au, bettina.berger@adelaide.edu.au