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Taking Care of Wildlings

By | Blog, Future Directions

By Hannes Dempewolf

We at the Global Crop Diversity Trust care about wildlings! No, not the people beyond The Wall, but the wild cousins of our domesticated crops. By collecting, conserving and using wild crop relatives, we hope to be able to adapt agriculture to climate change. This project is funded by the Government of Norway, in partnership with the Millennium Seed Bank at Kew in the UK, and many national and international research institutes around the world.

The first step of this project was to map and analyze the distribution patterns of hundreds of crop wild relatives. Next, we identified global priorities for collecting, and are now providing support to our national partners to collect these wild species and use them in pre-breeding efforts. An example of a crop we have already started pre-breeding is eggplant (aubergine). This crop, important in developing countries, has many wild relatives, which we are using to develop varieties that can better withstand abiotic stresses and variable environments.

More recently we have started a discussion with the crop science community on how best to share our data and information about these species, and genetic resources more generally. This discourse that was at the heart of what has now become the DivSeek Initiative, a Global Plant Council initiative that you can read more about in this GPC blog post by Gurdev Khush.

Why should you care?

Good question. I couldn’t possibly answer it better than Sandy Knapp, one of the Project’s recent reviewers, who speaks in the video below.

One of the great leaders in the field, Jack Harlan, also recognized their immense value: “When the crop you live by is threatened you will turn to any source of relief you can find. In most cases, it is the wild relatives that salvage the situation, and we can point very specifically to several examples in which genes from wild relatives stand between man and starvation or economic ruin.”

Oryza

Wild rice, Oryza officinalis, is being used to adapt commercial rice cultivars to climate change. Photo credit: IRRI photos, used under Creative Commons License 2.0

Crop wild relatives have indeed been used for many decades to improve crops and their value is well recognized by breeders. This is increasingly true also for abiotic stress tolerances, particularly relevant if we care about adapting our agricultural systems to climate change. One such example is the use of a wild rice (Oryza officinalis) to change the flowering time of the rice cultivar Koshihikari (Oryza sativa) to avoid the hottest part of the day.

Share the care

Fostering the community of those who care about crop wild relatives is an important objective of the project. We make sure that all the germplasm collected by partners is accessible to the global community for research and breeding, within the framework of the International Treaty on Plant Genetic Resources for Food and Agriculture (the ‘Plant Treaty’). The project invests into building capacity into collecting: it’s not as simple a process as it may sound. The following shows the training in collection in Uganda:

We also put a heavy emphasis on technology transfer and the development of lasting partnerships in all of the pre-breeding projects we support.

The only way we can safeguard and reap the benefits of the genetic diversity of crop wild relatives over the long term is by supporting a vibrant, committed community.  We hope you agree, and encourage you to get in touch via cropwildrelatives@croptrust.org.

To find out more about the Crop Trust and how you can take action to help conserve crop diversity for food security, please visit our webpage. For more information about the Crop Wild Relatives project, please visit www.cwrdiversity.org.

 

Genetic Diversity in our Food Systems

By | Blog, Future Directions
Gurdev Khush at IRRI

Gurdev Khush at IRRI. Photo credit: IRRI photos. Reproduced under a Creative Commons license 2.0

This week’s blog post has been written by agronomist and geneticist Gurdev Khush. Gurdev had a major role to play in the Green Revolution, and while working at the International Rice Research Institute (IRRI) developed more than 300 rice varieties, one of which (IR36) became the most widely planted variety of rice. The impact and significance of his work has been recognized by numerous awards including the World Food Prize in 1996, the Wolf Prize in Agriculture in 2000, the Golden Sickle Award in 2007, and in 1987 the Japan Prize.

Our civilization developed with the domestication of plants for food, fiber and shelter about 10,000 years ago. Since then we have made constant improvements to these domesticated plants based on genetic diversity. It is the conservation, evaluation and utilization of this genetic diversity that will be essential for further improvements in our food crops and world food security.

Gene banks conserve biodiversity

The first important step in conserving biodiversity was the establishment of a gene bank by Nikolai Vavilov at the Leningrad Seedbank in Russia during the 1920s. In subsequent years more gene banks were created in developed countries, and the Green Revolution provided major impetus for the establishment of gene banks in developing countries. The first gene bank for the conservation of rice germplasm was organized after IRRI was established in the Philippines in 1960. Other rice growing countries followed suit and now most of them have their own gene banks.

The IRRI gene bank has over 120,000 entries

IRRI medium term seed store

The medium term storage unit of the IRRI seed bank. Photo credit: IRRI photos. Reproduced under a Creative Commons license 2.0.

The IRRI gene bank has progressively grown from a few thousand entries in 1962 to over 120,000 entries today, including accessions of all the wild species. The germplasm is stored under two-temperature and humidity regimes. The medium term store keeps seeds at 4ºC and a relative humidity of 35% for 30–40 years, while in the longer term store, maintained at –10ºC and a relative humidity of 20%, seeds are expected to remain viable for 100 years.

IRRI accessions are evaluated for morphological traits, grain quality characteristics, disease and insect resistance, and for tolerance to abiotic stresses such as drought, floods, problem soils and adverse temperatures. These are all important characteristics in terms of breeding resilient and high yielding rice varieties for the future.

Selection of new rice varieties

Numerous landraces have been utilized for breeding high yielding rice varieties. The first high yielding variety, IR8, was developed from a cross between two landraces, one from Indonesia and the other from China. Another variety, IR64, is one of the most widely grown rice varieties, and has 19 landraces and one wild species in its ancestry.

IR64

Rice variety IR64, one of the most widely grown rice varieties. Photo credit: IRRI photos. Used under Creative Commons license 2.0.

Ensuring future food security

Gene banks have played an important role in world food security. However, as the population grows there are now even bigger challenges for meeting demand. Climate change and increased competition for land and water resources further magnify the problem. We need to breed climate resilient crop varieties with higher productivity, durable resistance to diseases and insects, and tolerance to abiotic stresses. Success will depend upon the continuous availability of genetic diversity; we must redouble our efforts to unlock the variability currently preserved in our gene banks.

Diversity Seek Initiative

Establishment of the Diversity Seek Initiative (DivSeek) and the proposed Digital Seed Bank, under the auspices of the Global Plant Council, is a welcome development.

The aim of DivSeek is to develop a unified, coordinated and cohesive information management platform to provide easy access to genotypic and phenotypic data on germplasm preserved in gene banks. It is an international effort to bring together gene bank curators, plant breeders and biological researchers. To begin with, the project will develop standards and generate genotypic, transcriptome and phenotypic information for cassava, rice and wheat diversity. This will form the foundation of the Digital Seed Bank, a novel type of database containing standardized and integrated molecular information on crop diversity. The information from this database will be publicly available, and will be of enormous scientific and practical value. It has the potential to significantly increase our understanding of the molecular basis of crop diversity, and its application in breeding programs.

If your organization is interested in joining DivSeek, information can be found here. Alternatively, sign up to the mailing list to keep up to date with the initiative.

Providing For Our Brave New World

By | Blog, Future Directions
The Journal of Experimental Botany (JXB) published a special issue in June entitled ‘Breeding plants to cope with future climate change’

The Journal of Experimental Botany (JXB) published a special issue in June entitled ‘Breeding plants to cope with future climate change

By Jonathan Ingram

The Journal of Experimental Botany (JXB) recently published a special issue entitled ‘Breeding plants to cope with future climate change’.

More often than not, climate change discussions are focused on debating the degree of change we are likely to experience, unpredictable weather scenarios, and politics. However, regardless of the hows and whys, it is now an undeniable fact that the climate will change in some way.

This JXB special issue focuses on the necessary and cutting edge research needed to breed plants that can cope under new conditions, which is essential for continued production of food and resources in the future.

The breadth of research required to address this problem is wide. The 12 reviews included in the issue cover aspects such as research planning and putting together integrated research programs, and more specific topics, such as the use of traditional landraces in breeding programs. Alongside these reviews, original research addresses some of the key questions using novel techniques and methodology. Critically, the research presented comes from a diversity of labs around the world, from European wheat fields to upland rice in Brazil. Taking a global view is essential in our adaptation to climate change.

Avoiding starvation

Why release this special issue now?

Quite simply, the consequences of an inadequate response to climate change are stark for the human population. In fact, as previously discussed on the Global Plant Council blog, changing climate and extreme weather events are already having an impact on food production. For example, drought in Australia (2007), Russia (2010) and South-East China (2013) all resulted in steep increases in food prices. However, a positive side effect of this was to put food security at the top of the global agenda.

A farm in China during drought. Reduced food production can cause steep rises in food prices leading to socio-economic problems.  Photo credit: Bert van Dijk used under Creative Commons License 2.0

A farm in China during drought. Reduced food production can cause steep rises in food prices leading to socio-economic problems.
Photo credit: Bert van Dijk used under Creative Commons License 2.0

Moving forwards, researchers and breeders alike will have to change their fundamental approach to developing novel varieties of crops. In the past, breeders have been highly succesful in increasing yields to feed a growing population. However, we now need to adapt to a rapidly changing and unpredictable environment.

Dr Bryan McKersie sums this up in his contribution to the special issue. He commented: “Current plant breeding methods use large populations and rigorous selection in field environments, but the future environment is different and does not exist yet. Lessons learned from the Green Revolution and development of genetically engineered crops suggest that a new interdisciplinary research plan is needed to achieve food security.”

Driving up yields

So which traits should we be studying to increase resilience to climate change in our crops?

A potentially important characteristic brought to the foreground by Dr Karine Chenu and colleagues (University of Queensland, Australia) is susceptibility to frost damage. Although seemingly counterintuitive at first, the changing climate could result in greater frost exposure at key phases of the crop lifecycle. Warmer temperatures, or clear and cool nights during a drought, would allow vulnerable tissue to emerge earlier in the spring (Gu et al., 2008; Zheng et al., 2012). A late frost could then be incredibly destructive to our agricultural systems, causing losses of up to 85% (Paulsen and Heyne, 1983; Boer et al., 1993).

As explained by Dr Chenu, “Finding frost tolerant lines would thus help to deal with frost damage but also with losses due to extreme heat and drought – as they could be avoided by earlier sowings”.

The authors conclude that a “national yield advantage of up to 20% could result from the breeding of frost tolerant lines if useful genetic variation can be found”. The impact of this for future agriculture is incredibly exciting.

This study is just one illustration of the importance of thinking outside the box and investigating a wide range of traits when looking to adapt crops to climate change.

You can find the full Breeding plants to cope with future climate change Special Issue of Journal of Experimental Botany here. Much of the research in the issue is freely available (open access).

Journal of Experimental Botany publishes an exciting mix of research, review and comment on fundamental questions of broad interest in plant science. Regular special issues highlight key areas.

References

Association of Applied Biologists. 2014. Breeding plants to cope with future climate change. Newsletter of the Association of Applied Biologists 81, Spring/Summer 2014.

Boer R, Campbell LC, Fletcher DJ. 1993. Characteristics of frost in a major wheat-growing region of Australia. Australian Journal of Agricultural Research 44, 1731–1743.

Gu L, Hanson PJ, Post WM et al. 2008. The 2007 Eastern US spring freeze: increased cold damage in a warming world? BioScience 58, 253–262.

Paulsen GM, Heyne EG. 1983. Grain production of winter wheat after spring freeze injury. Agronomy Journal 75, 705–707.

Zheng BY, Chenu K, Dreccer MF, Chapman SC. 2012. Breeding for the future: what are the potential impacts of future frost and heat events on sowing and flowering time requirements for Australian bread wheat (Triticum aestivum) varieties? Global Change Biology 18, 2899–2914.

James Wong: Plant Geeks Will Save The World!

By | Blog, Interviews

James Wong trained as a botanist at Kew Gardens in London, UK, before embarking on a wide and varied career encompassing broadcasting, writing and garden design. He demonstrates his passion for plants in every strand of his work, and is making a significant contribution towards raising the profile of horticulture and the plant sciences within the UK. He took some time out of his busy schedule to speak to Amelia at the Global Plant Council.

james wongJames qualified with a Masters in Ethnobotany; the study of how people use plants, in 2006. This branch of the plant sciences is very relevant to tackling pressing issues such as food security and conservation.

Plants have provided humanity with essentially every aspect of our sustenance and material culture for millennia. Being a fusion of anthropology and botany, ethnobotany is vital to understanding everything we are and everything we do.

 Humanity relies on an incredibly narrow range of plants to meet its needs, with just 3 crops providing up to 50% of our sustenance. This means civilization has pinned its future on just 0.00006% of the world’s edible plants!

With threats like climate change and a growing global population, it is simply not feasible to continue to marginalise 99.99994% of our crops. Learning about how to grow, prepare and eat those other plants is where the work of ethnobotanists is vital.

 This is just one example of how ethnobotany is essential in helping combat some of the biggest threats our species are facing in the next century. Plant geeks will indeed save the world.

To meet the needs of a growing population, many resources are currently focused on grow for flavourincreasing productivity of our large scale farming systems. However, in his most recent book, Grow for Flavour, James explores how we can increase the nutritional quality of home-grown produce. Could small-scale food production such as personal allotments or gardens have any role to play in our future food production systems?

In short, no. My tiny urban garden is just 6x6m, and there is no way that it is ever going to make a significant contribution to my calorie intake.

However (and this is a big however), even in this tiny space I can get access to a range of fruit and vegetables that could make an important contribution towards certain micronutrients in my diet. Many of these, including key phytonutrients, are not found in the limited range of crops grown commercially, at least in large quantities.

Green Zebra tomatoes are a good source of tomatidine.  Photo credit: J https://www.flickr.com/photos/florence_craye/2953736794/in/photolist-5v1F3s-6Pshmn-8 Used under a CC BY-NC-ND 2.0 license.

Green Zebra tomatoes are a good source of tomatidine.
Photo credit: J  Used under a CC BY-NC-ND 2.0 license.

For example tomatidine, a chemical found in green tomatoes, may help improve muscle tone and reduce atrophy according to some studies. It is not really found in any supermarket produce, yet I can easily grow 10 kgs of tasty, tomatidine-rich fruit like ‘Green Zebra’ each summer. Popped in the freezer they could provide me with an important source of this phytonutrient year round that would otherwise be almost totally absent in my diet.

Home gardens can make significant financial sense too, removing cost as a barrier to nutrient availability.

The garden design studio, Amphibian Designs, was co-founded by James in 2008. I have always been fascinated by plants and I feel that designing with them helps me express that.” This fascination has led the studio to win four Royal Horticultural Society medals for its designs, including two gold medals at the Chelsea Flower Show. Gardening is perhaps something we might associate more with art and creativity than science. However, James finds that: creating spaces with plants and arranging them to express an idea allows me to better understand their botany.” Furthermore, having a scientific rather than arts background can be advantageous in design.

 I have no formal design training and find this actually allows me more creative freedom! I rarely know the design rules and conventions, so I don’t feel I need to slavishly devote my works to them. There is an awful lot of assumed knowledge and entrenched ideas in horticulture, much of which has no factual basis, and being an outsider means you get to circumvent all that.

Engaging the public with the plant sciences is becoming increasingly important yet the perception that plants are boring can be difficult to overcome. Could gardens and horticulture provide a way to approach this problem?

Absolutely. Humans instinctively find plants beautiful. Sadly, I do think UK horticulture has done a rather good job of suppressing this instinct in many people by holding up a singular, historical ideal as the dominant mode of what a ‘proper’ garden should be. Between the rustic woven willow and stately home symbolism, it can be very easy for many people (like me) to not associate themselves with gardening. Would food, fashion, music, art or film limit themselves to such as singular ideal? Of course not, and that explains their far more broad-based appeal.

 One of the most popular stands I saw at Chelsea Flower Show this year was for the European Space Agency, and represented how plants would be grown in space to feed astronauts and fuel interplanetary discovery. The look of wonder in faces of the kids (of all ages) as they wandered through spoke volumes. What an amazing way to engage kids with science.

So, we can’t leave without asking one final question: any tips for the budding gardeners amongst our readers?

Plants always grow and look best when planted to echo how they would naturally grow in the wild. Doing so means you will have less work, healthier plants and a perfectly matching aesthetic almost every time. Google image your favourite plants in their wild habitat and try your best to match them. The rest will take care of itself!

Increasing Food Production in a Changing World

By | Blog, Global Change

The fifth report of the International Panel on Climate Change (IPCC) published last year announced that climate change is already negatively affecting our food supply and this problem is only going to be amplified in coming decades.

Our climate is projected to warm by 5ºC by 2050, with increased incidence of extreme weather events. Coinciding with this is a rapidly rising global population, predicted to reach 9.6 billion by 2050. Feeding all these extra mouths is challenge enough. Doing this under changing weather and climate conditions becomes even more difficult.

Food shortages resulting from population growth or unusual weather events can lead to rising food prices and political instability. A global rice shortage in 2008 saw prices rise by over 50%, resulting in riots in Asia and Africa. We might expect events such as this to become more common in the future as the food supply becomes more and more affected by climate change.

Not surprisingly food security is currently a buzz word in the research community, and many resources are being poured into trying to ensure a stable food supply for future generations.

Some climate skeptics argue that increases in carbon dioxide could boost plant growth, resulting in higher yielding plants under climate change. However, the reality is that any positive effect the increased CO2 could have on plant growth is likely to be outweighed by higher temperatures and extreme weather events.

Since the IPCC report there have been a number of studies focussed on the staple food crop wheat, and how yields could be affected in the future.

Wheat

Wheat was first domesticated 10,000 years ago and is now grown more widely than any other crop. Photo by jayneandd used under CC BY 2.0.

Wheat yields are sensitive to temperature, and are predicted to fall by around 6% for every 1ºC rise in temperature. If we do not cut down current emissions, the earth could warm by 5ºC by 2050, equating to a 30% reduction in wheat yields due to temperature increases alone.

This 30% reduction in yield is only the tip of the iceberg. Yields could be further reduced by increased instances of disease epidemics. For example, Fusarium Ear Blight is a wheat disease that causes spikelet bleaching and enhanced senescence. A severe epidemic can wipe out 60% of a wheat crop. In order to take effect, the disease requires wet weather at flowering, something which we can expect to happen more often in the future according to climate models.

Extreme weather events, such as flooding, are predicted to increase over the coming decades, and will cause unavoidable crop losses. This will exacerbate problems with declining yields, further increasing the difficulty of feeding a growing population.

What can we do?

Primarily, we should be trying to limit the extent of climate change, and to do so we need to act now. Reducing emissions and moving to sustainable energy sources should be at the top of the agenda.  However, most climate scientists agree that even if we act now to reduce our emissions, there will be at least 2ºC of warming, which is already impacting on food production.

We therefore need to make our food sources more resilient to climate change. In terms of wheat this means breeding varieties that are tolerant to higher temperatures and diseases. Additionally, we will need to adapt our farming methods, to be more intensive yet sustainable, and perhaps alter our diets.

Stress Resilience Forum, 23–25 October, Iguassu Falls, Brazil

In October the Global Plant Council, in collaboration with the Society of Experimental Biology, will bring together experts from around the world to discuss current research efforts in plant stress resilience. Abstract submission and registration for the Stress Resilience Forum is now open, and we welcome researchers at all levels to take part.

The meeting takes place immediately before the International Plant Molecular Biology Conference (25–30 October), also at Iguassu Falls, and which also includes several scientific sessions on plant stresses.

Can you crowdfund the sequencing of a plant genome?

By | Blog, Future Directions, Global Change
Dr Peng Jiang, University of Georgia, USA

Dr Peng Jiang, University of Georgia, USA

Peng Jiang and Hui Guo at the University of Georgia think you can! They are currently raising money via a crowdfunding approach to sequence the first cactus genome – but the question is: why would they want to? Peng explains all in this guest blog post.

A Prickly Proposal: Why Sequence the Cactus?
In these times of growing food insecurity due to climate change and population pressures, the prickly pear cactus (Opuntia ficus) has growing commercial and agricultural importance across much of the world – you will find it growing in Mexico and Brazil, Chile, large parts of India and South Africa, and in Spain and Morocco.

The goal of our proposal is to sequence the genome and transcriptome of the prickly pear cactus, a recognized food and forage crop in these challenging semiarid regions of the world.

With more than 130 genera and 1,500 species of Cactaceae, we will create a draft genomic and transcriptome database that would aid the understanding of this understudied plant family, and provide the research community with valuable resources for molecular breeding and genetic manipulation purposes. Here are some of the reasons why we think a first cactus genome would be so important:

The Prickly Pear Cactus

The Prickly Pear Cactus

1. Ecological Improvement
The beauty of the drought-tolerance cactus is that it can grow on desert-like wastelands. Nowadays, more than 35% of the earth’s surface is arid or semiarid, making it inadequate for most agricultural uses. Without efforts to curb global warming, “Thermageddon” may hit in 30–40 years time, causing desertification of the US, such that it may become like the Sahara. Opuntia helps create a vegetative cover, which improves soil regeneration and rainfall infiltration into the soil. This cactus genome research may help us to adapt our food crops to a much hotter, drier climate.

2. Food Crops, Feed and Medicine
The fruits of prickly pear cactus are edible and sold in stores under the name “tuna”. Prickly pear nectar is made with the juice and pulp of the fruits. The pads of prickly pears (“Nopalito”) are also eaten as a vegetable. Both the fruits and pads of prickly pears can help keep blood sugar levels stable because they contain rich, soluble fibers. The fruit contains vitamin C and was used as an early cure for scurvy.

Furthermore, there has been much medical interest in the prickly pear plant. Studies [1, 2, 3] have shown that the pectin contained in prickly pear pulp lowers cholesterol levels. Another study [4] found that the fibrous pectin in the fruit may lower a diabetic’s need for insulin. The plant also contains the antioxidant flavonoids quercetin, (+)-dihydroquercetin (taxifolin), quercetin 3-methyl ether (isorhamnetin) and kaempferol, which have a protective function against the DNA damage that leads to cancer.

3. Biofuels in Semiarid Regions
Planting low water use, Crassulacean acid metabolism (CAM; a water saving mode of photosynthesis) biofuel feedstocks on arid and semiarid lands could offer immediate and sustained biogas advantages. Opuntiapads have 8–12% dry matter, which is ideal for anaerobic digestion. With an arid climate, this prevents the need for extra irrigation or water to facilitate the anaerobic digestion process. Requiring only 300 mm of precipitation per year, Opuntiacan produce a large amount of dry matter feedstock and still retain enough moisture to facilitate biogas production. It’s possible to get as much as 2.5 kWh of methane from 1 kg of dry Opuntia.

4. Phylogenetic Importance
Trained botanists and amateurs alike have held cacti in high regard for centuries. The copious production of spines, lack of leaves, bizarre architecture and impressive ability to persist in the harshest environments on Earth are all traits that have entitled this lineage to be named a true wonder of the plant world.

The cacti are one of the most celebrated radiations of succulent plants. There has been much speculation about their age, but progress in dating cactus origins has been hindered by the lack of fossil data for cacti or their close relatives. Through whole genome sequencing, we help will reveal the genomic evolution of Opuntia by comparing this genome with that of other sequenced plant species.

Cacti are typical CAM plants. We will analyse the evolution of CAM genes in the cactus to help reveal the secret of drought tolerance. Furthermore, plant architecture genes and MADS-box gene family members will be analysed to reveal the specific architecture and structure of cactus.

Crowdfunding the Cactus Genome Project
Cactus has several fascinating aspects that are worth exploring, not just for its biology, but also its relevance to humanity and the global environment. We plan to generate a draft genome for Opuntia, and have launched a crowdfunding campaign to help fund this project – we have already raised $2300 USD (46% of what we need), but we only have 15 days to raise the rest. If you would like to help fund this project, please visit our Experiment page at: https://experiment.com/projects/sequencing-the-cactus-genome-to-discover-the-secret-of-drought-resistance.

If we are successful in raising enough money to initiate the Cactus Genome Project, not only will this be the first plant genome to be sequenced in the Cactaceae family, we will be releasing the results to the plant science community through GeneGarden, an ornamental plant genome database. Our citizen science approach is also allowing us to reach out directly to members of the public, creating exciting opportunities for outreach and engagement with plant science.

If you have any further questions, please contact project leader Dr Peng Jiang at pjiang@uga.edu.

This blog post is slightly adapted from a post originally appearing on GigaScience Journal’s GigaBlog. Reproduced and adapted with permission, under a CC-BY license.

References

  1. Wolfram RM, Kritz H, Efthimiou Y, et al. Effect of prickly pear (Opuntia robusta) on glucose- and lipid-metabolism in non-diabetics with hyperlipidemia – a pilot study. Wien Klin Wochenscr. 2002;114(19–20):840–6.
  2. Trejo-Gonzalez A, Gabriel-Ortiz G, Puebla-Perez AM, et al. A purified extract from prickly pear cactus (Opuntia fulignosa) controls experimentally induced diabetes in rats. J Ethnopharmacol. 1996;55(1):27–33.
  3. Fernandez ML, Lin EC, Trejo A, et al. Prickly pear (Opuntia sp.) pectin alters hepatic cholesterol metabolism without affecting cholesterol absorption in guinea pigs fed a hypercholesterolemic diet. J Nutr. 1994;124(6):817–24.
  4. Frati-Munari AC, Gordillo BE, Altamirano P, et al. Hypoglycemic effect of Opuntia streptacantha Lemaire in NIDDM. Diabetes Care. 1988:11(1):63–66.