plant crops

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).

Travel grant opportunity to attend the 34th Annual Root Biology Symposium

IPPN Root Phenotyping Working Group
Travel Grant for Researchers Using Phenotyping
IPG 2017, 34th Annual Root Biology Symposium
Columbia, Missouri, USA
7-9 June 2017

The IPPN Root Phenotyping Working Group (RPWG) encourages mobility among researchers and enhances international contacts between research groups. With this sponsorship grant RPWG  supports participation of Early Career Researchers at the IPG 2017, 34th Annual Root Biology Symposium.

  • Up to four grants of 500 EUR per researcher can be awarded.
  • 1 May 2017

Conditions:

  • You are affiliated with a university or a research institution and you are an early career scientist, PhD student, or postdoc who finished his PhD no later than ten years ago.
  • Please fill in the travel grant application and submit it to Saoirse Tracy.
  • The applications will be evaluated by the RPWG Board.

Last chance to secure an internship – apps close tomorrow!

This is your chance to investigate your plant science questions with the support of the highly skilled Australian Plant Phenomics Facility (APPF) team and the incredible technology and infrastructure we have available.

Internships are offered at the APPF in Adelaide and Canberra for enthusiastic, highly motivated postgraduate students with a real interest in our research and technology. Current postgraduate students in the following areas are encouraged to apply:

  • Agriculture
  • Bioinformatics
  • Biology
  • Biotechnology
  • Computer Science
  • Genetics
  • Mathematics
  • Plant physiology
  • Science
  • Software engineering
  • Statistics

Interstate students are strongly encouraged to apply!

We offer postgraduate internship grants which, in general, comprise:

  • $1,500 maximum towards accommodation in Adelaide or Canberra, if required
  • $500 maximum towards travel / airfare, if required
  • $10,000 maximum toward infrastructure use

The APPF has identified a number of priority research areas, each reflecting a global challenge and the role that advances in plant biology can play in providing a solution:

  • Tolerance to abiotic stress
  • Improving resource use efficiency in plants
  • Statistics and biometry
  • Application of mechatronic engineering to plant phenotyping
  • Application of image analysis techniques to understanding plant form and function

Students proposing other topics will also be considered.

APPF postgraduate internship grants involve access to the facility’s phenotyping capabilities to undertake collaborative projects and to work as an intern with the APPF team to learn about experimental design, image and data analysis in plant phenomics.

Selection is based on merit. Applications are assessed on the basis of academic record, research experience and appropriateness of the proposed research topic. Interviews may be conducted.

Postgraduate students are encouraged to contact APPF staff prior to submitting their application to discuss possible projects.

APPLICATIONS CLOSE:  31 March 2017. For further information click here.

 

Why apply for an internship with the APPF?

Well, aside from the fact we are a pretty nice bunch…

PhD student Rohan Riley, from Western Sydney University, undertook his research at APPF’s Adelaide node (The Plant Accelerator®) after being awarded a Postgraduate Student Internship Grant with us in 2015.

His research attempted to explain the unpredictability of plant growth responses in terms of resource limitation by introducing fungal communities to plants which are isolated from soils containing high or low levels of salinity and analysing the effects on plant stress at the phenotypic level.

This is what he had to say about his experience:

”Using daily phenotyping following the application of salt stress and controlled watering-to-weight in The Plant Accelerator® allowed for an unprecedented resolution and range of plant genetic changes in response to combinations of nutrient level, salinity and two different fungal communities that would not otherwise be achievable in a regular greenhouse,” said Rohan.

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”As a PhD student with limited experience in greenhouse experiments, the highly controlled growth conditions, large-scale automation, digital imaging and software technology (high-throughput phenotyping) at The Plant Accelerator® provided me with the work-space, expertise and technical support to make a complicated experiment possible.”

“It has been an amazing experience to conduct this experiment at The Plant Accelerator®. I am walking away from the facility with a big smile on my face, an incredible dataset for my PhD research and invaluable experience in greenhouse based plant research.”

To find out more about Rohan’s research:  https://www.researchgate.net/profile/Rohan_Riley

Sun protection and diversity could be key to more productive rice crops

With a rapidly growing population, improving the yield of global food staples such as rice has become an urgent focus for plant scientists.

In a recent study published on Plant Physiology, scientists have discovered they can improve rice productivity by selecting rice varieties that are better at capturing sunlight to produce grains instead of reflecting it as heat.

The team, which included Dr Xavier Sirault from the Australian Plant Phenomics Facility’s High Resolution Plant Phenomics Centre (APPF – HRPPC), focused on rice’s natural diversity by using traditional breeding techniques to select cultivated varieties – or cultivars – that are better at converting sunlight into food.

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“We studied hundreds of plants from five rice cultivars and found that there is variation between these varieties in relation to the quantity of light they use for growth or dissipate as heat. Some of them are capable of converting more sunlight into chemical energy, producing greater leaf area over time,” said lead researcher, Dr Katherine Meacham.

When leaves intercept sunlight, this sunlight is either; 1) absorbed by the leaf and converted via the process of photosynthesis into the plants own components; leaves, grains, roots, etc. 2) dissipated as heat as an strategy to protect the proteins of the plant from sun damage (photo-protection) or, 3) re-emitted as fluorescent light. In this study, the researchers measured fluorescence to infer the quantity of energy that is either converted into food or dissipated as heat.

“Recently scientists in the US found that they can produce transgenic plants that are better at catching sunlight without getting sun damage. Our work shows that this is also achievable by taking advantage of the natural variation of rice plants,” says Professor Robert Furbank, Director of the ARC Centre of Excellence for Translational Photosynthesis and one of the authors of this study.

“What is new about our research is that scientists had previously thought there was not much variation in how efficiently leaves could absorb and use light, and the reason for this is that they were not considering the full picture and measuring the plants throughout the entire day under natural illumination. We revealed that there are considerable differences between the five rice cultivars under moderate light and that means that there is room for selecting the most efficient plants,” said Professor Furbank.

“We found that there is room for improvement in some cultivars that can result in more photosynthesis without risking the plant’s protection strategies against sunlight damage.

The scientists measured fluorescence by clipping light receptors on leaves throughout a whole day to get a full picture of how the plant uses sunlight.

Traditional breeding for photosynthetic traits has not been a common strategy in any major cereal crop, in part due to the difficulty in measuring photosynthesis in thousands of plants. However, rapid screening tools are now available to study the interaction between the genes and the way they interact with the environment.

“Using unique facilities at the Australian Plant Phenomics Facility’s High Resolution Plant Phenomics Centre we were able to follow chlorophyll fluorescence in rice canopies throughout the entire day under natural illumination. This gave us completely different results when compared to the usual 30 min measurement of leaf level light use efficiency. By combining this with digital biomass analysis using PlantScan, we could link light use efficiency with growth, revealing genetic variation in rice varieties not previously detected,” said Professor Furbank.

“Our next step is to find varieties with superior photo-protection. We can directly use these for breeding and find the genes responsible. We have the capacity to screen many thousands of rice varieties for which we have gene sequence through the International Rice Research Institute,” said Dr Meacham.

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Measuring photosynthesis.  Photo credit:  International Rice Research Institute (IRRI)