Return to Resistance (Breeding Crops to Reduce Pesticide Dependence)-- Project!

General Discussions
,
1

Raoul Robinson wrote Return to Resistance, and Joseph just reminded me how it’s interesting and important and relevant to landrace gardening. It’s also pretty technical, dense, sometimes confusing, and most people don’t read it, and sometimes we might mis-remember things in it. For over a year, I’ve been thinking I need to read it again and write a summary of it. But… I can’t do that these days. So here is my proposal. Each person who wants to contribute reads a single chapter and summarizes it and puts that in a response below. We’ll re-organize it into a the correct order in a ‘wiki’ that will be a useful summary for people. We probably don’t need to include every single chapter. In the morning maybe I’ll make a google doc sign up form for chapters.

Here’s where to read the book for free:

http://www.sharebooks.com/system/files/Return-to-Resistance.pdf

3 Likes
2

It’s certainly dense. I’ve tried a couple of times but found it heavy going. Having chapter summaries is a great idea. I’ll sign up when the opportunity arises. It will force me to read at least one chapter thoroughly!

1 Like
3

I pulled out my copy to double check, the first several chapters cover the basic and I think most important part. That about resistance and the difference between vertical versus horizontal.

It’s a little bit like math, each chapter builds on the one before. If you read chapter four without first reading one - three you won’t know what he’s talking about, you can’t multiply if you can’t add.

You almost don’t have to read the rest of it, although I can’t imagine why you wouldn’t want to. :smile:

1 Like
4

Thanks for posting this. I was just about to go and search for the book! I was going to offer to summarize a chapter, but am now feeling a bit intimidated due to Ray’s and Mark’s comments about it. Anyway, I will contribute if I can.

1 Like
5

Perhaps it could be a longer-term project where Chapter 2 person waits until Chapter 1 is summarised to begin reading…

Of course, some potential issues with that, but ¯\ _ (ツ)_/¯. I do like the idea of this kind of ‘lazy’ book club!

2 Likes
6

Ok you guys are so awesome. This sounds good to me (sequential), but of course it sounds like a few people have already read it, so starting at a middle chapter might be OK for some. I made a start with a sign up sheet. Chapters are pretty short (usually less than 10 pages) so a person could easily sign up for more than one.

Return to Resistance Summary Project Sign Up - Google Sheets. I imagine people will just post their summaries in this thread, then we will combine and edit everything into a single wiki, I need to look into that a little more thoroughly.

7

Glancing at the pdf version, man I’d hate to read the whole thing that way, but anyway at a I glance I’ve forgotten how much there really is to digest in that book. I reckon I’ll have to read it all again for the third time.

For example, this little snippet caught my eye.

Horizontal resistance completely escaped the attention of the Mendelians. They were not interested in quantitative variation. They were working with qualitative resistances, inherited by single genes.

I am very interested in this qualitative vs quantitative aspect of inheritance regarding other traits as well, not just disease resistance. I’m convinced that nearly everything about sweet potatoes, from the color of the leaves to the sweetness of the roots is quantitative. I think it might also apply to aleurone color in corn and who know what else.

1 Like
8

For me the benefit to reading e-books is being able to highlight! Then come back and copy and paste the most important quotes, then summarize stuff in between.

For people who want the real book here is the cheapest version I see-- $45

Thriftbooks.com

9

Nope! Here is the cheapest and what I ordered last night! Lulu.com print on demand. Also, while it is still third edition it includes some 2013 revision, a year before Roaul passed away. Oddly that was very important to me because the winter of 12-13 is when I took my plant genetics course. So it is no more out of date than I am.

2 Likes
10

Well shucks, I didn’t know there were revised editions, I hope there is nothing significantly different, at least not in the basics of it, because my copy is from 1996. I hate when that happens.

11

I just dug my copy out and found that it’s also the original '96 version. It would be handy if there was a pamphlet outlining the changes.

2 Likes
13

At what “altitude” should we be summarizing? For instance, I just summarized chapter two (see below) and I’m wondering if that’s basically what we’re expecting for this project.

Chapter 2 - Plant Breeding: Pedigree Breeding and Population Crossing (1996)

There are two kinds of plant breeding. The Mendelians are interested in pedigree breeding, in which the focus is on moving single genes around to concentrate specific known desirable genes. The biometricians are interested in population breeding, in which the focus is on polygenes and their aggregate effects that distinguish an individual plant from the norm.

As an illustration of this distinction, pedigree breeders might find a desirable trait (e.g. blight resistance) in a wild example of a species and use multi-generational backcrossing to move that gene into a more bountiful (having been long-cultivated) population. Meanwhile, population breeders select seed from the “best” of the plants in a large population and found the next generation on those seeds, incrementally improving that overall quality without being concerned about any specific gene (early 19th century sugar-beet improvement is the example in the book).

The Mendelians gained an early prestige advantage over the biometricians because most major food crops are inbreeders and their techniques were better-suited to showing dramatic improvements. (Emasculating and manually crossing a few flowers is practical while doing so to a whole field is not.) This gap has been decreased through the rise of new technologies.

Other techniques and discoveries, such as developing pure-line varieties and the discovery of a single-gene rust-resistance in wheat also helped the Mendelians to seize control of plant-breeding at scale under the mistaken assumption that all pest-resistance was a matter of finding the right single-gene trait, setting crop production back through the whole of the 20th century.

2 Likes
14

It looks great to me. Might be useful to note which version you’re summarizing, and include a chapter heading in case they are different in different versions. Thank you!!

17

Preface (3rd. ed., rev. 2006)

To anyone who is concerned about the environment, it is obvious that all is not well with modern crop husbandry. One problem is that pests and diseases are destroying about one fifth of all crop production. A second problem is that these losses occur in spite of an extravagant use of chemical insecticides and fungicides that cost billions of dollars each year, worldwide.

This book is structured as 10 pairs of biological contrasts (Chapters 1-10), followed by some general conclusions (Chapters 11-17) and specific examples and techniques (Chapters 18-29).

This book is addressed mainly to readers who are concerned about the world food supply, and the pollution of our food and our environment with chemical pesticides, but who lack detailed scientific knowledge about these matters. It is also addressed to people who are not scientists, but who are prepared to make an effort to study a new subject that is outside their own fields of expertise.

The purpose of this book is to make public some rather specialised information that has remained obscure because of its technical nature. Technically informed readers will appreciate that the present account involves some deliberate over-simplification. Anyone requiring greater scientific detail is referred to appendices at the end of the book (also the writings of JE Vanderplank).

Let us now examine those ten pairs of biological contrasts!

3 Likes
18

Hmm, I think I didn’t quite complete my order or something. Nothing in my email about it. No charges. No book. Oops.

20

Chapter 1 Genetics: Mendelians and Biometricians (2013 edition, revised)
In 1900, 16 years after his death, Gregor Mendel’s work on inheritance of traits was rediscovered and its significance quickly appreciated. In that same year his work was republished in English, French and German and the Mendelian school of genetics was born.
Inheritance factors, now called genes, were discrete units, giving rise to an either/or situation. Simply put, if a red flowered plant crossed with a white flowered plant, the offspring would be either red or white flowered. The old school, known as Biometrics, viewed inheritance as a continuum. If a red flowered plant crossed with a white flowered plant the offspring might be red, white or any shade in between with many offspring being roughly half way between the two.
As time went by, researchers began to realise that many traits were not determined by a single gene (a monogenic trait) but rather by two, three or more genes (a polygenic trait). Polygenic traits did indeed show inheritance patterns similar to those described by the Biometricians.
Both schools, it turned out, were in some sense right. In subsequent years, this dichotomy of thought is echoed in plant breeding efforts, discussed further in the text.

4 Likes
21

Chapter 2: Plant Breeding: Pedigree Breeding and Population Breeding

I get the sense Mr Robinson is in favor of CMS breeding techniques.
I kept this long because it’s dense…
(Summarized by Chat gpt and edited by me)

The chapter describes the difference between two schools of genetics, Mendelians and biometricians, and their methods of plant breeding.

  • Mendelians deal with single-gene characters that are either present or absent and developed methods of plant breeding known as pedigree breeding, which involve gene-transfer techniques.
  • Biometricians, on the other hand, deal with many-gene characters that are continuously variable and developed methods of plant breeding known as population breeding, which involve changes in polygene frequency.
  • Mendelians usually faced the problem of getting a single-gene character they wanted to utilize in a cultivated plant out of a wild plant and into the cultivated plant. Genes are small pieces of DNA molecules, and it is difficult to transfer it from one plant to another. However, Mendelians have found a way to solve this problem in a way that is both ingenious and elegant.

Picture a wild plant that is immune to a fungus disease called “blight” and is hybridized with a cultivated plant that has a high yield of an excellent product but is highly susceptible to blight.
The crop yield and quality are both many-gene characters, while the resistance to blight is a single-gene character. The Mendelians would breed the wild plant with the cultivated plant to produce progeny that were mostly halfway between the two parents in their many-gene, quantitatively variable characters.

However, some of the progeny carry the single gene for resistance while others do not, and segregate into either resistant or susceptible individuals.

  • Mendelian genetics allows for identifying which plants carry the resistance gene by observing if they are not diseased with blight. The Mendelian breeder would throw out all the blighted plants and keep the blight-free plants.
  • As the resistant plants mature, the breeder would select the best one in terms of yield and quality and cross it with the original cultivated parent, known as back-crossing.

Mendelians used back crossing to restore the yield and quality of the hybrids while retaining the resistance gene. The progeny of the back-cross would have approximately three-quarters of the yield and quality of the original cultivated parent and only one-quarter of the poor yield and quality of the wild parent. The breeder would continue to select the best resistant individuals for multiple generations of back-crossing until the yield and quality of the hybrids are restored and possibly even better than the original cultivated parent. This gene-transfer technique was so clever that it captured the imagination of plant breeders all over the world.

The biometricians’ technique of population breeding involves working with large populations of plants, screening the entire population for a small minority of the best plants, randomly cross-pollinating them among themselves and repeating this process for multiple generations until no further progress is possible. A classic example of population breeding is the increase of sugar content in fodder beet to nearly 20% and the total yield of roots considerably, which resulted in the creation of a new crop called sugar beet.

  • All flowering plants can be classified into two categories: out-breeders and in-breeders, based on their natural method of pollination. Out-breeders are cross-pollinating plants while in-breeders are self-pollinating plants.
  • Pedigree breeders work with carefully controlled crosses in which the parents of each cross are known and recorded. These crosses are made by hand, through artificial pollination, which can be labor-intensive depending on the species of plant being pollinated. One of the advantages of pedigree breeding is that relatively few crosses are necessary and, thus, hand-pollination is feasible.

The biometricians relied on large numbers of natural cross-pollinations, which made it slow, difficult, and often impractical to work with in-breeding species. This gave a clear advantage to the Mendelians as most of the important food crops of the world such as wheat, rice, peas, and beans are in-breeders.

Nowadays, this difficulty is no longer a problem as there are various techniques for overcoming it, such as using a substance called a male gametocide. The text also mentions that in the days of the genetic conflict, these alternative techniques were not available, and the Mendelians appeared to be winning in terms of practical plant breeding.

In 1905, a Danish botanist, W.L. Johannsen, discovered the pure line technique which allows seed-propagated crops to breed true to type, preserving agriculturally valuable characteristics like high yield and high quality of crop product. This was a big boost for the Mendelians and a further advantage in their conflict with the biometricians.

Additionally, in the same year, a British scientist, R.H. Biffin, made a discovery that resistance to a disease of wheat called rust was inherited in a Mendelian fashion, which provided the Mendelians with a single-gene character of economic significance and it quickly transpired that the inheritance of resistance to many other plant diseases was controlled by single genes. Plant breeding has benefited from these single-gene resistances to crop parasites, otherwise it would have remained quantitative. However, this belief that all resistances to all crop parasites were controlled by single genes became a shibboleth, a myth, that has dominated and plagued the whole of twentieth century crop science.

4 Likes
23

Here’s my summery of chapter 4 infection: allo-infection and auto infection from the free pdf version of “Return to Resistance”. Any feedback is welcome.

24

Thank you Lora!!! These will be compiled into one document, would you mind copy and pasting?

25

Chapter 4
Allo-Infection and Auto-infection

Raoul writes a strict definition for the purpose of his book of the word Infection: contact made by one parasite individual with one host individual for the purpose of parasitism.

There are two kinds of infection. The two kinds of infection are called allo-infection and auto-infection.

Derived from ancient Greek, allo means other or different. An allo-infection happens when the host plant is infected by a parasite that had to travel to its new host. In this case the parasite came from another different host or it was in an independent state of dormancy.

The ancient greek word auto means self. An auto-infection happens when the host is infected by a parasite individual that was born on or in the host individual. The parasite had no need to travel.

Next, Raoul uses an analogy of people traveling to explain the two types if infection: “Think of an individual host plant as an island surrounded by sea. Allo-infection is then equivalent to an immigrant arriving on that island, by boat or plane, from somewhere else. Auto-infection is the equivalent of the colonization of that island by the descendants of that immigrant.” Using this traveling people analogy Raoul goes on to make three main points about parasitic infection.

If the island is deserted the first person to inhabit it must come from outside. The first infection of any plant host must be allo-infection.
Colonization can proceed only after immigration is successful. Auto-infection can only occur after there has been matching allo-infection.
When colonization continues repeatedly, over generations, the island will become crowded. Individuals may begin leaving, searching for a new host to allo-infect.

Analyzing real life examples, such as the lifecycle of common parasite like aphids can help to further illustrate the critically important difference between the two types of infection. Aphids have several morphologically different forms, each with a specific purpose. The winged aphid is equipped for travel and the allo-infection of a host plant while the wingless aphid serves the purpose of auto-infection.

If a plant is completely free of aphids the only possible infection is an allo-infection requiring the winged aphid. Once this allo-infecting and invariably female aphid arrives it begins to feed on the plant and reproduce. It can reproduce without sex and with live births rather then laying eggs like most other insects! This sexless reproduction is the same as vegetative propagation in plants; all the progeny are genetically identical clones!

Without the need for egg laying the aphid saves a lot of time. The young are all female and wingless because travel is not necessary for auto-infection. They grow rapidly and soon start their own eggless, sexless reproduction! This type of rapid auto-infection causes a population explosion which eventually results in crowding and stimulates the birth of winged individuals who fly off to allo-infect other hosts somewhere else. Ecologists call this type of reproduction r-strategy. Most of the serious pests and diseases are r-strategy species and it’s their population explosions that can be so alarming, damaging and difficult to control.

Another real life example concerns a fungal disease of coffee trees called rust. Coffee trees and the fungal parasite coffee leaf rust are both native to Africa but in 1970 it made it’s first appearance in Brazil, the worlds largest coffee producer. Thankfully it did not end up severely effecting the coffee farms. Coffee rust is caused by a microscopic fungus that reproduce by spores so small they can’t be observed by the naked eye. Scientists in east Africa discovered that these spores are sticky and resistant to becoming airborne but are freely dispersed in water. Then later, Brazilian scientists showed the disease was wind borne and spreading at a rate of hundreds of miles per year. What was argued over then is clearly evident now and that is that coffee rust spores have two completely different states and they can apparently change freely from one to the other. So far no one has discovered what makes them do this but the most likely factor is atmospheric humidity. The function of the non-sticky spores is allo-infection and the function of the sticky spores is auto-infection.

For 100 years crop science and plant breeding have proceeded, heavily focused on two distinct types of pollination, cross-pollination and self-pollination, (allogamous plants and autogamous plants) without recognition for the two distinct types of infection, allo-infection and auto-infection. We must now recognize this less obvious but equally important distinction.

2 Likes