Where does our food come from?

James Wong

There’s been quite a bit of discussion in the Twittersphere in recent weeks that caught my attention, about the sources and origins of our food, in which botanist, science writer, and broadcaster James Wong (@Botanygeek) has been a lively participant (expertly educating, and oftentimes correcting misinformation that surfaces all too frequently on Twitter).

So where does our food come from? No, I’m not referring to the local supermarket! Nor the countries where it’s grown and exported to the UK, to land on our supermarket shelves, such as avocados from Peru or French beans (Phaseolus spp.) from Kenya, to mention just a couple of examples.

Rather, I’m talking about the regions of the world where our food crops were first domesticated from wild species [1]. In many farmers’ fields, there is still an enormous diversity of shapes, sizes, and colors, as well as response to different growing conditions or reaction to pests and diseases. Just take the example below of potatoes from Peru, varieties that have been carefully cultivated by generations of farmers in the high Andes.

(L): Farmer varieties of potatoes from Peru; and (R): a potato farmer and her husband from the Province of Cajamarca in the north of Peru proudly holding a prized variety.

These diverse crop varieties and related wild species are the genetic resources or agrobiodiversity (perhaps a term more familiar to most through its regular use in the media) that plant breeders need to enhance agricultural productivity, transferring genes between different varieties or species to keep one step or more ahead of changing climates or increased threat of new strains of plant diseases. Without access to this valuable genetic variation, plant breeders would be challenged indeed to respond appropriately to the many threats in the agricultural environment.

There is an ongoing interdependence among countries for access to genetic resources. Take the potato, for example, with which I am quite familiar. The UK potato crop ultimately depends for its survival on plant breeders being able to access different genes and breed them into new varieties. Where do these genes come from? From from cultivated and wild potatoes in Peru and neighbouring countries. Plant breeders at the James Hutton Institute in Dundee, Scotland, regularly dip into the species conserved in the Commonwealth Potato Collection. This potato example is repeated worldwide for most other crops.

Colin Khoury

In a significant open access article (published in the Proceedings of the Royal Society B in 2016) Colin Khoury (a Birmingham MSc genetic resources graduate) and his co-authors state: Research into the origins of food plants has led to the recognition that specific geographical regions around the world have been of particular importance to the development of agricultural crops . . . We estimate the degree to which countries use crops from regions of diversity other than their own (‘foreign crops’), and quantify changes in this usage over the past 50 years. Countries are highly interconnected with regard to primary regions of diversity of the
crops they cultivate and/or consume.

Colin followed up with a piece on the blog of the Union of Concerned Scientists in 2017, discussing the interdependence of nations: The evidence on countries’ predominant use of foreign crops bolsters the rationale for strengthening international collaboration on conservation of crop diversity and for making the exchange of all agricultural seeds as easy and affordable as possible. Our interdependence also boosts the argument for considering the genetic diversity of globally important food crops as public goods which should be openly available to all, and for respecting the rights of farmers to practice their traditional methods of conservation and exchange, not only in recognition of their historical contributions to the diversity in our food, but also in active support of its further evolution.

Just take a look at this interesting graphic (click to enlarge) that was published in the 2016 paper, and republished in the 2017 blog post. I think many readers of my blog will be surprised when they discover the origins of most of the food plants they take for granted.

Origins and primary regions of diversity of major agricultural crops. Source: Khoury et al. 2016. Proc. R. Soc. B 283(1832): 20160792.

However, the concept of centers of origins and crop diversity is not a new one. It was first formulated by the great Russian geneticist (and ‘father of plant genetic resources’), Nikolai Ivanovich Vavilov (born in 1887). See how his centers coincide with the map above. Vavilov’s ideas have been reworked since his death, but still provide a fundamental foundation for the study and understanding of crop diversity. He was starved to death in one of Stalin’s prisons in 1943.

I. The Tropical Center; II. The East Asiatic Center; III. The Southwest Asiatic Center (c0ntaining [a] the Caucasian Center, [b] the Near East Centre, [c] the Northwestern Indian Center; IV. The Mediterranean Center; V. Abyssinia; VI. The Central American Center (containing [a] the mountains of southern Mexico, [b] the Central American Center, [c] the West Indian islands; and VI. The Andean Center.

One of his great works, Five Continents (a memoir of his many plant collecting expeditions) was republished in 1997 on the occasion of his 110th birthday. It had never appeared during his lifetime.

Vavilov, NI, 1997. Five Continents. International Plant Genetic Resources Institute, Rome, Italy. ISBN: 92-9043-302-7

Then, as I was thinking through these ideas about food origins, I came across the two photos below. At first I couldn’t recall where they had been taken. Then I realized they must have been taken during the drinks reception after the half-day N.I. Vavilov Centenary Symposium, jointly organized by the Linnean Society of London and the Institute of Archaeology of University College London on 26 November 1987 to commemorate Vavilov’s birth. I was one of the speakers.

Top: with Joe Smartt (University of Southampton). Bottom: Chatting with Joe Smartt, with Prof. Jacks Hawkes (University of Birmingham, to my left) with another symposium attendee.

The papers were published in a special edition of the Biological Journal of the Linnean Society in January 1990.

Sadly, all my fellow presenters have since passed away [2].

In the first paper, 1. Preface, Jack Hawkes and David Harris state the following: Vavilov laid the foundations of modern plant breeding, stressing the importance of the wide range of genetic diversity in our ancient crops and in related wild species—a diversity that before his time had barely been used or understood by breeders . . . Not only this—the whole movement of crop genetic resources conservation as a necessary prerequisite for the new more resistant and productive varieties needed now and in the future can be clearly traced back to Vavilov’s seminal ideas . . . Vavilov’s theoretical studies on crop plant origins and evolution under domestication, the areas in which crops evolved and the parallelism in their diversity in particular regions also possess clear practical implications, as well as linking into prehistory and the beginnings of agriculture.

In the second paper, Jack Hawkes discussed the impact of Vavilov’s work. He had met the great man on his visit to the Soviet Union in 1938.

Geographer David Harris discussed the origins of agriculture and how Vavilov’s studies on the centers of origin influenced the work of many other scholars. Yet he concluded that with the discovery of new evidence about the origins of agriculture, Vavilov’s concept as such had outlived its usefulness.

I was privileged to be asked to contribute to this symposium, standing alongside three colleagues: Joe Smartt, Jack Hawkes, and Trevor Williams who had encouraged me to enter the world of genetic resources and supervised my research, and mentored me at various stages of my career.

Professor Hugh Bunting had been the external examiner to the Birmingham MSc Course on genetic resources when I presented my dissertation on lentils in September 1971. There was a link to Vavilov there, because his second wife, Elena Barulina, wrote the first monograph on lentils.

My own paper discussed how homologous variation among potato species was evident when looking for resistance to pests and diseases.

I only met Gordon Hillman on one occasion at this symposium. He made very significant contributions to our understanding of early farming systems and the domestication of cereals in the Near East.

In his paper, Hugh Bunting discussed how Vavilov promoted the inclusion of physiological and biochemical features alongside descriptions of morphology to understand how plants were adapted to their environments. The examples used were groundnuts and sorghum, crops which Bunting had studied in Africa over many years.

In the final paper, Trevor Williams (who was Director of the International Board of Plant Genetic Resources, IBPGR, the forerunner of the International Plant Genetic Resources Institute, IPGRI, and Bioversity International) discussed how IBPGR’s program of collecting and conserving crop varieties and wild species worldwide had been guided by Vavilov’s ideas on centers of diversity.

As you can see, there’s more to this story of our food and its origins than perhaps meets the eye initially. It’s a story that I have followed for the past 50 years since I first set out on my career conserving and using plant genetic resources.

[1] Avocados originated in Central America, and French beans come from South America.

[2] I’ve not been able to find any further information about Stuart Davies, co-author with Gordon Hillman, since his retirement from Cardiff University.

This book (ISBN: 90-220-0785-5), by Anton Zeven and Jan de Wet, published by the Centre for Agricultural Publishing and Documentation in Wageningen in 1982 is an excellent source of information about the crop and wild species found in the centers of diversity.

It was a revised second edition of: Zeven AC and PM Zhukovsky, 1975. Dictionary of cultivated plants and their centres of diversity.

Zhukovsky was a follower of Vavilov and further developed the idea of centers of origin and diversity.

Lentils (and Mrs. Vavilov) on my mind . . .

Nikolai Ivanovich Vavilov (1887-1943)—The Father of Plant Genetic Resources—is one of my scientific heroes. Yet I knew nothing about him until September 1970 when I began my graduate studies concerning the conservation and use of plant genetic resources at The University of Birmingham (in the Department of Botany as it was then).

Last Saturday, 26 January, was the 76th anniversary of Vavilov’s death in a Soviet prison.

Prison photos of Vavilov.

Vavilov’s grave in Saratov.

Botanist, science writer, and broadcaster James Wong (@Botanygeek) posted a short thread of tweets about Vavilov. So, I tweeted a reply to James about three scientists (two I worked with; the other I’d been introduced to) who met Vavilov in the 1930s.

I followed up with another  tweet.

Actually, Elena Barulina (1896-1957) was Vavilov’s second wife who passed away just two years after Vavilov had been ‘rehabilitated’ by the Soviet government, as she was working her way through his various publications.

Vavilov had first married Ekaterina Saharova in 1912, and they had one son, Oleg (born 1918).

Vavilov with his first wife Ekaterina, and son Oleg.

Vavilov divorced Ekaterina in 1926 and married Elena; they had one son, Yuri (born 1928). Both Oleg and Yuri became physicists, like their renowned uncle Sergey, Nikolai’s younger brother. Ekaterina died in 1963 never having remarried.

Elena Barulina and Nikolai Vavilov.

Elena (Helena) Barulina was an international lentil expert, publishing an important monograph in 1930. During the course of 1970-71, I got to know this publication in great detail.

So how did I get involved with lentils, and what was the outcome? As part of the MSc course requirements at Birmingham, each student had to present a short dissertation. I opted to carry out a study of crop variation, but first I had to choose the species for my study.

Trevor Williams

My dissertation supervisor was Dr J Trevor Williams (who went on to become the first Director General of the International Board for Plant Genetic Resources or IBPGR (that then became the International Plant Genetic Resources Institute or IPGRI, and is now Bioversity International) in Rome.

In November 1970, we scanned the pages of Flora Europaea, looking for potential targets among the various legume species. And there, under the cultivated lentil (Lens culinaris) was the important comment: Origin unknown. Now there was a challenge if ever we saw one!

Lentil is an ancient crop, associated with the earliest developments and spread of agriculture in the Near East and Mediterranean, and this is where the wild lentil species are also found. When I began my study, there were just five recognized lentil species (this was increased to seven in a 2015 paper):

  • Lens culinaris (the cultivated species)
  • L. orientalis
  • L. nigricans
  • L. ervoides
  • L. montbretii (now regarded as a species of Vicia)

I presented my dissertation, Studies in the genus Lens Miller with special reference to Lens culinaris Medik., in September 1971, having used Barulina’s monograph as my lentil ‘Bible’ throughout.

I grew a large field trial of lentil varieties and, from my analysis of the variation in morphological characters, some chromatographic analyses, and growth pattern relationships, concluded that the small- and large-seeded forms described by Barulina as subsp. microsperma and subsp. macrosperma were the extremes of a continuous variation pattern, and not correlated with geographical origin. Similar small- and large-seeded forms can also be seen in other legumes like faba bean and grasspea.

To analyze the relationships between the different lentil species, I spent several days working in the Herbarium at the Royal Botanic Gardens at Kew, measuring variation in many morphological characters on as many herbarium specimens of lentil species I could get my hands on. I also borrowed herbarium specimens from several other herbaria. In all I must have looked at least a couple of hundred herbarium sheets.

Hybrid indices for lentil species.

Species were compared by constructing hybrid indices (a numerical method developed and first described in 1949 by renowned American botanist, Edgar Anderson—another scientific hero of mine—in his seminal publication Introgressive Hybridization). This allowed me to determine to what extent variation patterns in lentil species overlapped, or were distinct. Click on the image to the right to see an enlarged version of the resulting hybrid indices.

While the variation patterns between some species were quite distinct, the continuity in variation between L. orientalis and L. culinaris led me to the conclusion that we might be describing a wild species progenitor-domesticate relationship. And, indeed, this is what I proposed in my dissertation.

A year later, the eminent Israeli botanist Daniel Zohary actually published a paper¹ in the scientific journal Economic Botany arriving at the same conclusion. The studies I commenced in 1970-71 were continued by Carmen Sánchez Kilner the following year, and in our 1974 paper we proposed that L. culinaris and L. orientalis were subspecies of the same species, L. culinaris. In 1979, another Israeli botanist, Gideon Ladizinsky, reached the same conclusion based on hybridization experiments and cytogenetic analysis, in a paper published in Euphytica.

Today, I’m sure students would dive straight into analyses of molecular markers to clarify the taxonomy and species relationships. Almost 50 years ago these techniques were not available, so we had to rely on a thorough analysis of species morphology, an approach that is often regarded today as ‘old hat’ but still remains the solid foundation of plant taxonomy. It was an approach that served us well, and our conclusions were corroborated by others later on.

I see my studies on lentils as an important link to Vavilov and his colleagues such as Elena Barulina. Also, in later research, I drew on Vavilov’s Law of Homologous Series and its relevance to potatoes, especially with regard to resistance to the cyst nematode (Globodera spp.).

It’s also interesting to note just how relevant the ‘Vavilov approach’ still is today (76 years after his death), guiding the exploration and use plant genetic resources to increase agricultural productivity, which was the focus of my career over 40 years.

¹ Zohary, D., 1972. The wild progenitor and the place of origin of the cultivated lentil, Lens culinaris. Econ. Bot. 26: 326–332.

Standing on Vavilov’s shoulders . . .

Nikolai Ivanovich Vavilov (1887-1943). Not a name familiar to many people. Vavilov is, however, one of my scientific heroes.

Until I began graduate school in September 1970, when I joined the MSc course at the University of Birmingham on Conservation and Utilization of Plant Genetic Resources, I’d never even heard of him. In fact, looking back, I’m rather surprised that his name didn’t crop up once during my undergraduate years. I’d been encouraged to apply for a place on the Birmingham course by a lecturer in genetics at Southampton University, Dr Joe Smartt. But Vavilov and his work was not on the curriculum of botany courses that I took.

In preparation for Birmingham, I’d been advised to purchase and absorb a book that was published earlier that year, edited by Sir Otto Frankel and Erna Bennett [1] on genetic resources, and dedicated to NI Vavilov. And I came across Vavilov’s name for the first time in the first line of the Preface written by Frankel, and in the first chapter on Genetic resources by Frankel and Bennett. I should state that this was at the beginning of the genetic resources movement, a term coined by Frankel and Bennett at the end of the 60s when they had mobilized efforts to collect and conserve the wealth of diversity of crop varieties (and their wild relatives) – often referred to as landraces – grown all around the world, but were in danger of being lost as newly-bred varieties were adopted by farmers. The so-called Green Revolution had begun to accelerate the replacement of the landrace varieties, particularly among cereals like wheat and rice.

Thus began my fascination with Vavilov’s work, and a career in genetic resources in a broad sense that was to last 40 years until my retirement in 2010.

Vavilov was a botanist, geneticist and plant breeder who rose to the top of agricultural research in the Soviet Union who, through his many expeditions around the world (described in the book Five Continents [2], published posthumously in English in 1997) assembled a vast array of diversity in many crop species. Vavilov developed two seminal theories of crop evolution, which have influenced the science of genetic resources ever since.

The first was his Centers of Diversity and Origin, in which he stated that “the place of origin of a species of a cultivated plant is to be found in the area which contains the largest number of genetic varieties of this plant.” While we now appreciate that this was an oversimplification, his ideas about the origin of crop diversity have been the foundation for much of the genetic resources exploration carried out in subsequent decades.

The second was his Law of Homologous Series in the Case of Variation, published in Russian in 1920 and in English in 1922. I applied this concept in my search for pest resistance in wild potatoes, which I presented at a Symposium organized by the Linnean Society of London and the Institute of Archaeology, University College, London in 1987 to celebrate the centenary of Vavilov’s birth [3].

Vavilov died of starvation in prison at the relatively young age of 55, following persecution under Stalin through the shenanigans of the charlatan Trofim Lysenko. Lysenko’s legacy also included the rejection of Mendelian genetics in the Soviet Union for many years. Eventually Vavilov was rehabilitated, long after his death, and he was commemorated on postage stamps at the time of his centennial.

Although never having the privilege of knowing Vavilov, I do feel that I met him vicariously through three people I have known, who did meet him, and I worked with two of these for many years.

First, Sir Otto Frankel FRS, who I first met at a genetic resources meeting in Jakarta in the mid-80s, was an eminent wheat breeder and geneticist, and one of the founders of the genetic resources movement. Originally from Austria, he had escaped before the Nazis came to power, and moved to New Zealand and Australia afterwards. Frankel visited Vavilov in Leningrad (now St Petersburg again) in 1935.

Jack Hawkes, Mason Professor of Botany at the University of Birmingham and my PhD supervisor, travelled to Leningrad in 1938 to consult with Vavilov’s colleague, SM Bukasov, about the potatoes he had collected in South America. He wrote about his meeting with Vavilov, which he presented at the Vavilov Symposium referred to above [4].

John S Niederhauser was an eminent plant pathologist who spent many years researching the potato late blight fungus in Mexico. He was awarded the World Food Prize in 1990. I worked for several years with John in the 1970s when I was regional leader for the International Potato Center in Costa Rica, and we were developing and implementing what turned out to be the first consortium, PRECODEPA (Cooperative Regional Potato Program – in four Central American countries, Mexico and the Dominican Republic), of the Consultative Group on International Agricultural Research (CGIAR). As a young man of about 17, so John told me, he’d asked a travel agent how far he would be able to travel (return) from San Francisco with the money he had available: Leningrad was the destination. Walking around a research garden there one day, he was approached by a kindly gentleman – Vavilov as it turned out – who offered him the chance to work for a few weeks harvesting germplasm evaluation trials on one of his institute’s research stations in the Soviet southeast.

What all three emphasised – in their writings or related to me personally – was Vavilov’s friendliness, generosity of spirit, his boundless energy, and above all, his humanity, and that he treated everyone as an equal, even young persons as Hawkes and Niederhauser were when they met him.

Vavilov’s legacy endures. He is recognized as one of the giants of 20th century biology. And he has been an inspiration for countless students of genetic resources conservation and use.

[1] Frankel, OH & E Bennett (eds), 1970. Genetic Resources in Plants – their Exploration and Conservation. IBP Handbook No 11. International Biological Programme, London and Blackwell Scientific Publications, Oxford and Edinburgh. pp. 554. SBN 632 05730 0.

[2] Vavilov, NI, 1997. Five Continents. International Plant Genetic Resources Institute, Rome, Italy. pp. 198. ISBN 92-9043-302-7.

[3] Jackson, MT, 1990. Vavilov’s Law of Homologous Series – is it relevant to potatoes? Biological Journal of the Linnean Society 39, 17-25.

[4] Hawkes, JG, 1990. NI Vavilov – the man and his work. Biological Journal of the Linnean Society 39, 3-6.