Novel technique to study root system architecture brings breakthrough in crop production

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In a world first, researchers from The University of Western Australia and The International Centre for Agricultural Research in the Dry Areas (ICARDA) have published a study that will allow chickpea breeders and researches to develop new chickpea varieties with improved adaptation to target environments.

The variability of root architectural traits was characterised across 270 chickpea genotypes including the core collection, providing the basis for breeding new varieties with suitable root traits, to efficiently access soil nutrients and water, and adapt to drought and other stresses.

Dr Yinglong Chen from UWA’s Institute of Agriculture and School of Earth and Environment used a novel semi-hydroponic platform to rapidly measure the two-dimensional root system architecture with minimal disturbance to plant growth, and without destructive root sampling. 

Dr Chen said the study identified chickpea genotypes with vastly different root properties, which can be used with follow-up investigations to identify candidate genotypes with desirable root traits targeted to specific environments.

“Drought stress, particularly at the end of the growing season is a major constraint limiting chickpea production and yield stability in arid and semiarid regions of the world,” Dr Chen said.

“This study identified deep rooting genotypes which may have the advantage of accessing subsoil reserves of water when the topsoil dries out later in the season in Mediterranean climates such as the southern Australian grainbelt.”

The results highlighted genotype groups that could be crossed to identify the genetic basis of specific root traits, which may help to characterise those traits suitable for targeted genotype selection, and breeding of new chickpea varieties for efficient use of water and nutrients. 

United Nations Food and Agricultural Organization’s International Year of Pulses 2016 Special Ambassador and project leader Hackett Professor Kadambot Siddique said the research is ground-breaking because stresses such as drought and low-fertility soils are the main factors restricting the production of chickpea and other major crops in many countries.

“Globally, drought stress reduces chickpea production by an estimated 33%, of which approximately 19% could be managed through genetic improvement efforts,” Professor Siddique said.

“Chickpea is a highly nutritious pulse crop grown on about 12 million hectares of land from temperate to sub-tropical regions of the world, so this study has the potential to make a huge impact to global food and nutritional security.”

The findings were published in the paper Characterising root trait variability in chickpea (Cicer arietinum L.) germplasm,in Journal of Experimental Botany. The research was supported by the CGIAR Research Program on Grain Legumes in collaboration with The International Centre for Agricultural Research in the Dry Areas (ICARDA).

Media references

Dr Yinglong Chen (The UWA Institute of Agriculture) 

Period12 Oct 2016 → 1 Sep 2017

Media coverage

8

Media coverage

  • TitleRoot science in a wheelie bin
    Degree of recognitionInternational
    Media name/outletGRDC GroundCover
    Media typeWeb
    CountryAustralia
    Date1/09/17
    DescriptionDr Yinglong Chen has developed a semi-hydroponic method to characterise variation in root architecture among 270 chickpea lines that represent a high proportion of the world’s chickpea genetic diversity.

    Above-ground plant traits are the prime focus of breeding programs, but what goes on below the ground is also becoming an increasingly intense area of research. To gain traction in this area, methods had to be invented to rapidly visualise differences in root architecture within large and genetically diverse plant populations. Only with this ability to contrast and compare the world’s genetic biodiversity does it become possible to start selecting different kinds of root traits based on an understanding of their impact on crop productivity.

    Just such a root-imaging method has been developed at the University of Western Australia (UWA) by Dr Yinglong Chen, who works at UWA’s Institute of Agriculture and School of Agriculture and Environment.

    The development work was done using narrowleaf lupins and the method has now been applied to a population of 270 chickpea lines sourced from Australia and around the world, supported by the Consultative Group on International Agricultural Research’s (CGIAR) Program for Grain Legumes.

    Despite the large number of plants analysed, the populations could be characterised efficiently for root trait variability in a relatively small area, overcoming one of the major constraints that has limited root research in the past. Dr Chen and his colleagues established a semi-hydroponic system that can screen hundreds of lines in a temperature-controlled glasshouse.

    The new protocol involves germinating seed in sand and transplanting the emerged plants into growth pouches bracketed with clear perspex panels, which are slotted into wheelie bins containing low-level nutrient solution and moistened by a water pump-spraying system. The side of the pouches can be removed, allowing the root architecture to be photographed and measured during the course of the experiment.

    The system allows plants to grow up to six weeks, with maximal root depths of around 110 centimetres. At harvest, root systems are imaged and subsamples of roots at various depths are collected for morphological and architectural measurements.

    Dr Chen says that this method was applied to a core chickpea collection – which included a high proportion of the world’s genetic resources – and identified considerable variation in root traits (see Table 1). Included were long lateral roots, deeper roots with sparse branching, and fine roots.

    “We identified about 30 root-related traits, 17 of which were of interest for further analysis,” Dr Chen says. “There is certainly enough diversity to allow us to identify genetic-based differences that work best in different environments. We now also have the option to combine some of these different traits.”

    The core chickpea collection consisted primarily of landraces, but also included advanced cultivars, breeding material and two wild relatives of chickpea (C. echinospernum and C. reticulatum), sourced from India. Other countries of origin were: Australia, Turkey, Pakistan, Iran, Ethiopia, Russia, Nigeria, Chile, Germany, Nepal, Mexico, Bangladesh, Myanmar, Cyprus, Morocco, Tanzania, Syria, Malawi, China, Portugal, Algeria and Israel. Seed was multiplied at a UWA field station in Perth from the collection provided by the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).

    Stress Tests
    The next task is to understand what differences in chickpea root architecture mean relative to stress adaptation, crop productivity and yield constraints. Dr Chen is testing a subset of the chickpea lines – the ones with the most diverse root systems – in glasshouse systems that allow him to subject the chickpea lines to various stresses, especially relating to drought and nutrient deficiency.

    “Drought stress, particularly at the end of the growing season, is a major constraint limiting chickpea production and yield stability in arid and semi-arid regions of the world,” Dr Chen says. “However, studies have shown that a prolific root system in chickpeas is closely associated with grain yield under drought.

    “Among the diversity we saw in the chickpea collection was deep-rooting genotypes that had nearly twice the taproot length as the shallow-rooting genotypes. Genotypes with deeper roots may have the advantage of accessing subsoil reserves of water when the topsoil dries out later in the season in Mediterranean climates, including the southern Australian grainbelt.”

    It will take several years to generate strong associations between particular root traits and desirable gains in productivity, such as greater resilience to dry conditions. However, by the time the associations are detected, tested and field validated, the project will be in a position to fast-track its findings to breeding programs given the outputs from an ICRISAT collaboration.

    Dr Chen explains that his team is also collaborating with ICRISAT’s Dr Rajeev Varshney, who has sequenced the genomes of the chickpea core collection. That means unique genetic signatures that distinguish the chickpea lines can be identified, allowing for the ultra-rapid development of the DNA markers that breeders will eventually need to select for desirable root traits.

    Project leader Professor Kadambot Siddique, who was the Special Ambassador for the United Nations Food and Agricultural Organization’s International Year of Pulses 2016, says the research could result in significant improvements in future varieties given that drought and low-fertility soils are the main factors restricting the production of chickpeas and other major crops in many countries.

    “Globally, drought stress reduces chickpea production by an estimated 33 per cent, of which about 19 per cent could be managed through genetic improvements,” Professor Siddique says. “Chickpeas are a highly nutritious pulse crop grown on about 12 million hectares of land from temperate to subtropical regions of the world, so this study has the potential to impact on global food and nutrition security.”

    In addition, there are collaborations that are applying the novel, semi-hydroponic, wheelie bin phenotyping system in wild genotypes of narrowleaf lupins, in bread wheat and barley varieties.
    Producer/AuthorDr Gio Braidotti
    URLhttps://grdc.com.au/resources-and-publications/groundcover/groundcovertm-130-september-october-2017/root-science-in-a-wheelie-bin
    PersonsYinglong Chen
  • TitleHigh-tech agriculture can prevent oncoming global water wars
    Degree of recognitionNational
    Media name/outletThe Conversation
    Media typeWeb
    CountryAustralia
    Date9/01/17
    DescriptionForget about oil or gas – you should be worrying about the less discussed but far more concerning fact that the world is running out of clean, drinkable water.

    I wrote this article while in Kathmandu. Nepal’s capital and largest city has a severe water shortage. Even though all homeowners pay a fee to the government to get water on tap, supplies run only once a week for a few hours. Desperate residents are then forced to purchase water from private suppliers. While this is affordable for richer people, it’s a big problem for the lower and middle classes. For many in the developing world, water is really the difference between prosperity and poverty.

    More than a billion people around the world have no reasonable access to fresh water. Most of the diseases in developing countries are associated with water, causing millions of deaths each year (a child is estimated to die from diarrhoea every 17 seconds).

    Given all this, we have to come up with a solution to global water use fast, before water scarcity becomes a major cause of international conflict.

    The vast majority of our water is found in the oceans. Only 3% is fresh and can be used for farming and drinking, and in any case most of this is frozen in glaciers and polar ice caps. That means just 0.5% of the Earth’s water is accessible and, of this, more than two thirds is used in agriculture.

    If we’re going to cut back on our water usage, we have to focus on making our farms more sustainable and efficient. With the global population still growing, we’ll need to produce ever more crops using less water, in less agricultural land.

    Worldwide, just over a third (37%) of the land that could be used to grow crops is currently used. Potential farmland is available, but it’s not developed due a lack of infrastructure, forest cover or conservation. A lack of land isn’t really a big problem as of now – but water is.

    Go beyond traditional farming

    So how to grow crops using less water? One option would be to find a sustainable way to remove salt from our (essentially infinite) reserves of sea water. The farm in South Australia pictured below uses energy from the sun to extract seawater and desalinate it to create fresh water, which can be used to grow crops in large greenhouses.

    Such farms are based in barren areas, and the plants are grown with hydroponics systems that don’t require soil. Growing crops like this all year round would significantly reduce freshwater usage in hot and dry regions, but the cost of setting up these greenhouses remains an issue.

    Water shortages would also ease significantly if farmers could simply use less water to produce the same yield. Easier said than done, of course, but this is especially important in drought-prone areas.

    Plant scientists around the world are busy identifying genes that enable plant growth in arid, dry conditions. For example, what is it that makes upland rice grow in dry soil while lowland rice requires well irrigated paddy fields for growth?
    Once the keys to drought tolerance are identified, they can be introduced in crops through genetic engineering (and no, this doesn’t involve injecting food with toxins as suggested by a Google image search).

    Farmers traditionally bred drought tolerant crops through the slow and painstaking process of selection and crossing over many generations. Genetic engineering (GE) provides a short-cut.

    A recent study identified diverse root architecture systems in different chickpea varieties [Chen et al. 2017. Characterising root trait variability in chickpea (Cicer arietinum L.) germplasm. Journal of Experimental Botany 68: 1987–1999]. Future studies hope to identify genes that make some roots efficient at capturing water and nutrients from dry soils. Once a genetic factor is identified, scientists are able to directly deliver the gene that helps plants to capture more water.

    A key factor for drought-tolerance in plants is the plant hormone abscisic acid (ABA), which increases plants’ water efficiency in droughts. But ABA also reduces the efficiency of photosynthesis, which reduces plant growth in the longer term, and as a result crop yields decrease.
    Producer/AuthorRupesh Paudyal
    URLtheconversation.com/high-tech-agriculture-can-prevent-oncoming-global-water-wars-70746
    PersonsYinglong Chen
  • TitleHigh-tech agriculture can prevent oncoming global water wars
    Degree of recognitionInternational
    Media name/outletPHYSORG (Science X Network)
    Media typeWeb
    CountryUnited States
    Date9/01/17
    Producer/AuthorRupesh Paudyal
    URLhttps://phys.org/news/2017-01-high-tech-agriculture-oncoming-global-waterwars.html
    PersonsYinglong Chen
  • TitleHigh-tech agriculture can prevent oncoming global water wars
    Degree of recognitionInternational
    Media name/outletEco-Business
    Media typeWeb
    CountryAustralia
    Date9/01/17
    URLhttps://www.eco-business.com/opinion/high-tech-agriculture-can-prevent-oncoming-global-water-wars/
    PersonsYinglong Chen
  • TitleHigh-tech agriculture can prevent oncoming global water wars
    Degree of recognitionInternational
    Media name/outletThe Independent
    Media typeWeb
    CountryUnited Kingdom
    Date9/01/17
    URLhttps://www.independent.co.uk/environment/high-tech-agriculture-can-prevent-oncoming-global-water-wars-a7506041.html
    PersonsYinglong Chen
  • TitleHigh-tech agriculture can prevent oncoming global water wars
    Degree of recognitionInternational
    Media name/outletNewsweek
    Media typeWeb
    CountryUnited States
    Date9/01/17
    URLhttps://www.newsweek.com/clean-water-water-supply-technology-agriculture-progress-536820
    PersonsYinglong Chen
  • TitleNovel technique to study root system architecture brings breakthrough in crop production
    Degree of recognitionInternational
    Media name/outletPremium Official News (Pakistan)
    Media typeWeb
    CountryPakistan
    Date17/10/16
    PersonsYinglong Chen
  • TitleNovel technique to study root system architecture brings breakthrough in crop production
    Degree of recognitionInternational
    Media name/outletSeedQuest (United States)
    Media typeWeb
    CountryUnited States
    Date12/10/16
    URLhttps://www.seedquest.com/news.php?type=news&id_article=81796&id_region=&id_category=&id_crop=
    PersonsYinglong Chen

Media contributions

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Media contributions

Keywords

  • chickpea
  • root system architecture
  • crop production
  • breakthrough
  • breeding