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♫We’ll rock your world!♫

 Comparative genomics in cereals, Crop breeding, Genomics, Researchers, Rice  No Responses »
Sep 072012
 
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“It is very rare that scientists can take their projects wherever they go. I’ve been very lucky to be able to do this, and much of this has to do with the support I’ve received from GCP.” – Matthias Wissuwa

In the world of phosphorus, Matthias (pictured) is somewhat of a ‘rock star, not that he would admit to it. We don’t understand why not, since to borrow his words, the project he’s involved has becoming something of a ‘celebrity project’ in the scientific community.

For  a decade-and-a-half, he has searched tirelessly for a rice gene that could improve the crop’s yield in phosphorus-deficient soils –which make up half of the world’s soils. Last month, his transnational team published in Nature that their 15-year quest had ended, having finally found the elusive gene – Pup1.

We celebrate this happy ending, especially as we had the added pleasure of talking to Matthias recently: it was delightful in listening to the modest German recount the long journey which has taken him from his home town of Hamburg, to USA, Japan, The Philippines and back to Japan, all this while,  faithfully ‘carrying’ Pup1 with him as he switched employers. As you’ve seen, Japan scores a double strike, so our ‘rock star’ is also ‘big on Japan’! 

Talking to Matthias, we could sense the achievement was only just sinking in – that he and his team’s years of laboratory work was becoming a practical reality that will aid rice-growing farmers from Africa to Asia,  and hopefully other grain growers in years to come. Here’s what Matthias had to say…

You started this project back in 1997. Tell us how you became interested in phosphorus deficiency and rice.

After completing my PhD in the United States, I accepted a postdoc position in Tsukuba, Japan, with the National Institute of Agro-Environmental Sciences (NIAES). It was an easy decision because my wife is Japanese.

My postdoc host, Dr Ae was interested in phosphorus, particularly in legumes. I originally started work on tolerance to phosphorus deficiency in groundnuts, but soon changed to rice to take advantage of the molecular tools available for rice.

Tsukuba is a very new city. It’s called The Science City in Japan because the Japanese government built it to house all the national research institutes. This was great for me as I became interested in QTL mapping, which was pioneered by scientists in Tsukuba. I got talking to people in the rice research community in Tsukuba and was introduced to Dr Yano, who was developing mapping populations for rice at the National Institute of Agrobiological Sciences. He kindly gave me his populations and that’s how I started to map QTL for phosphorus-deficiency tolerance in rice.

Dr Ae was perplexed by my decision, believing that studying legumes was far more challenging than rice. He always told me: “Rice is boring. They just make long, fine roots to capture phosphorus.” That was 15 years ago and he turned out to be right. Long roots are the secret for phosphorus uptake in rice, particular in Kasalath and varieties like that.

Field trials for phosporus-efficient rice in The Philippines.

Did you share Dr Ae’s hypothesis that longer roots were the secret to some rice varieties being able to tolerate phosphorus-deficient soils?

For a long time, I was not sure if it was just long roots. It was a real chicken-and-egg scenario – does strong phosphorus uptake spur root growth, or the other way around?

As it turns out, it is the latter – plants growing longer roots help with the uptake of more phosphorus – and Pup1 is responsible for this.

We have now shifted our aim and are looking for varieties of rice tolerant to phosphorus-deficient soils that either:

  • release organic acids, phosphatases or some other compound that makes phosphorus more readily available for the plant to absorb, or
  • manipulate soil microorganisms to favour those that can aid in making phosphorus more soluble, or
  • very efficiently utilise phosphorus once it is taken up.

All three mechanisms are found in legumes, so there is reason to believe that they exist in rice and we are now working on finding them.

GCP has been interested in the project since 2004 as its outcome aligns with GCP’s goals to improve crop yields and security in developing countries… It has become something of a ‘celebrity project’ in the scientific community, attracting researchers to work on the project or collaborate with us.

In 2002 you left NIAES and accepted a position with the International Rice Research Institute (IRRI), and were encouraged to continue your work on Pup1. When you moved back to Tsukuba in 2005 to accept the position you currently hold with the Japan International Research Center for Agricultural Sciences (JIRCAS), you were again encouraged to continue your Pup1 project, collaborating with your successor at IRRI, Dr Sigrid Heuer. How important has it been to you and the project to have the support of your institutes?

It is very rare that scientists can take their projects wherever they go. I’ve been very lucky to be able to do this, and much of this has to do with the support I’ve received from GCP. They’ve been interested in the project since 2004 as its outcome aligns with GCP’s goals to improve crop yields and security in developing countries.

When I left IRRI, Sigrid was just starting and was more or less free to take on the project, so I asked her if she’d be interested in continuing my work with Pup1 at IRRI and collaborate with me in Japan. She was actually the perfect person for the project because her background in molecular biology complemented my background as a plant breeder.

Over the past seven years, we have worked together very well, and with the addition of Rico Gamuyao, a PhD student supervised by Sigrid, things have recently progressed quite quickly to the point that we were able to pinpoint Pup1.

So GCP has played a major role along your journey?

Yes, definitely. The support from GCP on the Pup1 project, now in its 8th year, was instrumental at getting this project to where it is.

Quite simply, the funding from GCP allowed us to hire Rico as well as Juan Pariasca-Tanaka, a project scientist with me at JIRCAS. Neither Sigrid nor myself had the time to do all the hands-on work so having both Rico and Juan has been hugely helpful.

How important has the collaboration between IRRI and JIRCAS been for the project?

Are they playing with mud? Not at all! Working. Matthias (L) and Rico (R) have zipped up their boots and gone back to their bee…er…. we mean, roots, mucking mud here as they do some fieldwork related to the search for PSTOL1.

Tremendously important. Sigrid’s group at IRRI is relatively small as is mine in Japan, so we rely on each other’s complementary expertise when working on complicated projects.

We have also been fortunate to have constant interest in the project from the scientific community. It has become something of a ‘celebrity project’, and as such, attracted researchers to work on the project or collaborate with us.

For example, we are working with two US groups at Cornell University and Penn State, that are also funded by GCP, trying to track down Pup1 in other crops and identifying genes that control root architecture, and how different architectures may affect P uptake.

These collaborations are really exciting, and make it possible to answer questions that we could not answer ourselves, or that we would have overlooked, were it not for the partnerships.

It really has been a team effort and we wouldn’t have got to where we are now without all the help of everyone involved

You’ve been described as the Godfather and Guru of Pup1. How do compliments like this make you feel?

It makes me laugh but of course it’s a very well-meant comment, and to some extent, considering I’ve worked on it for 15 years, you could say that there is some truth to it.

I’ve done all the original work, but Sigrid has been just as instrumental. She did the part where my expertise was no longer adequate – the molecular side, looking at genes and thinking about the function of a gene and testing for its function.

It really has been a team effort and we wouldn’t have got to where we are now without all the help of everyone involved, which also includes the support of Dr Yano over the years.

…phosphorus deficiency is a worldwide problem that has recently gained public attention because of how expensive phosphate fertilisers have become…Farmers are always interested in saving money and improving yields and we believe this discovery will help with both.

Have you been surprised by the attention this project has received?

As I said, the project has always been in the scientific spotlight because it was the first to map a major QTL for phosphorus uptake.

We knew from the Sub1 story – the submergence tolerance gene, which was published in Nature 4–5 years ago – that the media would probably be interested in this similar discovery. I’m still very surprised that this unsexy story has caused such interest.

You have to remember though, phosphorus deficiency is a worldwide problem that has recently gained public attention because of how expensive phosphate fertilisers have become. About four years ago, the price almost tripled and continues to stay high.

Farmers are always interested in saving money and improving yields and we believe this discovery will help with both.

Phosphorus deficiency is probably even more critical in Africa than it is in Asia… This means Pup1 may have its biggest impact in Africa.

How will the research continue?

Having focused so much on the basic research, we now want to turn our attention to the application. IRRI and JIRCAS will train national breeding programmes to use marker-assisted selection and help them breed their own rice varieties with Pup1.

Sigrid and IRRI are mainly working with Asian national breeding programmes and we at JIRCAS focus more on African programmes such as the Africa Rice Center. Phosphorus deficiency is probably even more critical in Africa than it is in Asia, as phosphate fertilisers aren’t used nearly as much as they are in Asia. This means Pup1 may have its biggest impact in Africa.

We are also looking for new sources of tolerance to phosphorus-deficiency. One very exciting project involves West African rice (Oryza glaberrima) the father of the Nerica ™ (New Rice for Africa) varieties.

So far, we have found that this rice is very tolerant to phosphorus-deficient soils. It does have Pup1, but in addition harbours novel genes that also enhance performance on phosphorus-deficient soils.

We hope to discover a Pup2 in the years to come.

Links

 

Rooting for the key to more phosphorus for rice

 Comparative genomics in cereals, Crop breeding, Genetics, Genomics, Rice  3 Responses »
Sep 072012
 
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Preparing rice root samples (Photo: IRRI)ALL IN THE ROOTS: A plant’s roots are a marvellously multitalented organ. They act as fingers and mouths helping plants forage and absorb water and nutrients. They act like arms and legs offering a sturdy base of support so a plant doesn’t keel over. They help store food and water, like our stomach and fat cells. And in some plants, can spawn new life – we leave that to your imagination!

That is why it is of little surprise that this multitalented organ was the key to discovering why some rice lines yield better in phosphorus-poor soils, a puzzle whose answer has eluded farmers and researchers… until now.  And even better, the findings hold promise for sorghum, maize and wheat too. Please read on!

 In search of the key – The Gene Trackers
In 1999, Dr Matthias Wissuwa, now with the Japan International Research Centre for Agricultural Sciences (JIRCAS), deduced that Kasalath, a northern Indian rice variety, contained one or more genes that allowed it to grow successfully in low-phosphorus conditions.

For years, Matthias made it his mission to find these genes, only to find it was as easy as finding a needle in a genetic haystack. He teamed up with the International Rice Research Institute (IRRI), and with GCP’s support, the gene trackers were able to narrow the search down to five genes of interest.

“We had started with 68 genes and within three years, we had narrowed in on these five candidate genes. And then, one-by-one, we checked whether they were related to phosphorous uptake,” recollects Dr Sigrid Heuer, senior scientist at IRRI and leader of the team that published the discovery in Nature in August 2012.

Sigrid Heuer at a rice phosphorus uptake demonstration field in The Philippines.

“In the end we found that if a certain protein kinase gene was turned on in tolerant plants like Kasalath, then those plants would perform better in phosphorus-deficient soils.”

They named this protein kinase gene PSTOL1, which stands for Phosphorus Starvation Tolerance. “When we put this gene into intolerant rice varieties that did not have this gene, they performed better in phosphorus-deficient soils.”

The importance of phosphorus
Rice, like all plants, needs phosphorus to survive and thrive. It’s a key element in plant metabolism, root growth, maturity and yield. Plants deficient in phosphorus are often stunted.

Sigrid explains that whereas phosphorus is abundant in most soils, it is however not always easily accessible by plants. “Many soil types bond tightly to phosphorus, surrendering only a tiny amount to plant roots. This is why more than half of the world’s rice lands are phosphorus-deficient.”

Farmers can get around this by applying phosphate fertilisers. However this is a very expensive exercise and is not an option for the majority of the world’s rice growers, especially the poorer ones –the price of rock phosphate has more than doubled since 2007. The practice is also not sustainable since it is a finite resource.

By selecting for rice varieties with PSTOL1, growers will be less reliant on phosphate fertilisers.

How it works: unravelling PSTOL1 mechanics
In phosphorus-poor soils, PSTOL1 switches on during the early stage of root development. The gene tells the plant to grow larger longer roots, which are able to forage through more soil to absorb and store more nutrients.

“By having a larger root surface area, plants can explore a greater area in the soil and find more phosphorus than usual,” says Sigrid. “It’s like having a larger sponge to absorb more water.”

A rice variety — IR-74 — with Pup1 (left) and without Pup1 (right).

Although the researchers focussed on this one key nutrient, they found the extra root growth helped with other vital elements like nitrogen and potassium.

Another by-chance discovery was that phosphorus uptake 1 (Pup1), the collection of genes (locus) where PSTOL1 is found, is present within a large group of rice varieties.

“We found that in upland rice varieties – those bred for drought-prone environments – most have Pup1,” says Sigrid. “So the breeders in these regions have, without knowing it, been selecting for phosphorus tolerance.”

“When thinking about it, it makes sense as phosphorus is very immobile in dry soils, therefore these plants would have had to adapt to grow longer roots to reach water deeper in the soil and this, at the same time, helps to access more reservoirs of phosphorous .”

Breeding for phosphorus tolerance, and going beyond rice
Using conventional breeding methods, Sigrid says that her team introduced PSTOL1 into two irrigated rice varieties and three Indonesian upland varieties, and found that this increased yields by up to 20 percent.

“In our pot experiments,” she added, “when we use soil that is really low in phosphorus, we see yield increases of 60 percent and more. This will mean growers of upland rice varieties will probably benefit the most from these new lines, which is pleasing given they are among the poorest rice growers in the world.”

Read how Indonesian researchers are developing their own breeds of upland rice with the PSTOL1 gene

Sigrid also sheds light on broadening the research to other crop varieties: “The project team is currently looking at Pup1 in sorghum and maize and we are just about to start on wheat.”

Building capacity and ensuring impact
Like all GCP projects, this one invests as much time in building capacity for country breeding programmes as on research.

Sigrid and her team are currently conducting the first Pup1 workshop to train researchers from Bangladesh, India, Indonesia, Nepal, Philippines, Thailand and Vietnam. They will share molecular markers that indicate the presence of PSTOL1, techniques to select for the gene, as well as for new phosphorus-efficient varieties.

Breeding for phosphorus-efficient rice in the Philippines.

“The aim of these workshops is to take these important tools to where they are most needed and allow them to evolve according to the needs and requirements of each country,” says Dr Rajeev Varshney, GCP’s Comparative and Applied Genomics Leader. “Breeders will be able to breed new rice varieties faster and more easily, and with 100 percent certainty that their rice plants will have the gene. Within three to five years, each country will be able to breed varieties identical to those that growers know and trust except that they will now have the Pup1 gene and an improved ability to unlock and take up soil phosphorus.”

Joining hands in collaboration
This IRRI-led project was conducted in collaboration with JIRCAS and the Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development (ICABIOGRAD) working with the Indonesian Centre for Rice Research. Other partners included: Italy’s University of Milano, Germany’s Max Planck Institute in Golm, the University of The Philippines at Los Baños, USA’s Cornell University and University of California (Davis and Riverside), Brazil’s EMBRAPA, Africa Rice Center, Iran’s Agricultural Biotechnology Research Institute, Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO) and University of Dhaka in Bangladesh.

Links

Sigrid’s presentation at the GCP General Research Meeting 2011

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