Saturday, November 9, 2013

Breeding for Rust Resistance in Daylilies - Part 1

Breeding for Rust Resistance in Daylilies:
Part 1

This is the first part in a series of blog posts that are actually one document I have been working on for the last couple of years. It is simply far too long, with far too many topics and too much information to be made into one post. For our first installment, I wanted to give a short overview of my background and experience and then introduce one simple concept - the difference between hobby breeding and professional research breeding. The first few posts will deal with concepts. Then we will move on to actual breeding methods in the later posts. It is important to get our concepts and definitions under out belt before we get into any complicated breeding strategies.

With that said, one of my goals with this series of posts is to make this information accessible to hobbyists. I will at times use the language of science, but I will also go out of my way to either offer examples or use more common language that the average hobbyist can relate to. The goal of this series is to demystify 'resistance breeding' and to help you, the hobbyist breeder, to see that breeding for some level of rust resistance is not some magical endeavor beyond the scope of the average backyard breeder, and that it is actually possible to approach selection for rust (or any other pathogen) just in the manner you currently approach any other trait you select for.

You don't have to have a PhD, a laboratory or many acres of grow-out fields to make some progress in selecting for resistance, any more than you have to have those things to make progress selecting for better branching, cool morning opening, dormant foliage or any of the many other traits you already select for. 

Introduction and Bio

First, I would like to present some of my background for those who do not know me and are not familiar with my work in selection and breeding for disease resistance over the last two decades.

It is important to state first and foremost that I am not a professional genetic researcher affiliated with any university or industry. I am an independent researcher and breeder, but I have worked with several professional researchers over the last two decades in my research and the practical application of my findings through breeding and selection.

My road to working with immuno-genetics (the study of genetic, heritable disease resistance) started early due to the fact that every group of animals or plants I worked with from childhood on was beset by some plague or another. For many years, through my childhood and into my early twenties, I followed the standard prescription of ‘medicate, and then medicate some more’. Over time though, I came to realize that this was no answer, only a prophylactic to keep the problem invisible.

In the early nineteen-nineties I began breeding rare chickens to study their feather color and patterning genes as well as their feathering and form genes. However, the most immediate issue became clear very quickly: chronic disease. At first I considered inbreeding to be the source of the suppressed immune systems, but even in very wide outcrosses, the problems persisted. Then I had blood work done and found the causative pathogens. Medications were prescribed, but they did nothing more than mask the problems and as soon as the treatment was withdrawn, the problems returned within 7-10 days.

So that set me on a path of research to understand how people in the pre-medication past dealt with such problems, what the poultry research community had learned about genes that impart resistance to given pathogens and how to practically apply that information to a breeding program to produce lines of genetically resistant birds. To spare the reader and daylily enthusiast the pain of reading many pages of details about breeding for chicken disease resistance, I will simply state that through combining multiple genes for resistance, I have been able to create lines that are fully immune for two major pathogens: Mycoplasma gallisepticum and the Marek’s Virus complex.

Practical Breeding versus Scientific Research

I want to state for the record that there is a difference between what we do as breeders and the research and experimentation we may pursue, and the research that is done by scientists in university or industry settings. It is so important to emphasize that they are not the same thing. I have done both types of ‘research’ and I know that they are both useful and have their place. I want to stress the difference in these two approaches, because I do not want any of the real professional researchers who may read this to assume that I don’t know the difference, or that I am leading any lay-persons reading this to believe that one is the equivalent of the other.

Professional research is designed to obtain factual, quantifiable, replicable proof of a given issue. Breeding research and experimentation is to allow the breeder to make advances in their chosen goals and intelligent choices in their own breeding programs, to gain the desired results. Professional research is important, but it often does not translate well to the hobbyist breeder and may even be relatively useless for practical application by hobbyist breeders. Conversely, hobbyist research and experimentation is aimed toward achieving desired results, and often has little value to the professional researcher because it does not follow the strict controls of real scientific research programs and generally the hobbyist is not working with the numbers required to acquire sufficient data to make claims of proof. Our results in the hobby tend toward being evidence of a particular pattern of heritability, but are generally not proof as the professionals mean the term, and it is important to recognize this up front. This, of course, is generally of little concern to the hobbyist breeder who only wants to be able to replicate desired results with some accuracy.

With that said though, I will state that while the professionals are seeking quantifiable, replicable proof, the breeder is generally only seeking indications of trends that can help them achieve their desired results. For instance, professionals will often criticize hobbyist breeders for making claims such as ‘so-and-so shows resistance or immunity, recessiveness or dominance, single gene or quantitative effects, etc’, because to the professional researcher, such a claim could only be made after sufficient numbers had been observed under strict protocols to prove such a statement in a quantifiable, replicable manner. However, the breeder really doesn’t need that kind of proof to pursue a breeding program. The breeder only wants to see trends that appear to fit such patterns of inheritance so that he or she can have some idea of how to pursue a breeding program to obtain the desired results.

For instance, Dr. Stout had no proof, in the current scientific sense, that a red daylily could be created. Yet, he spent twenty years pursuing the goal and created ‘THERON’, the first red daylily hybrid, as a result. Further, no scientific research project was initiated to prove that toothed, wildly ruffled or pie-crusted edges could be bred onto daylilies. Instead, breeders simply pursued the goal of such edges based on the presence of very minute examples of such edges. Through breeding such individual cultivars together, selecting for the highest expression of the trait and continually concentrating the target trait, such edges became a reality. We can see the results of that effort and selection process today. The presence of such edges in many modern daylily cultivars is proof, after the fact, that such edges are possible, but there was no proof at the beginning, only the suggestion that such was possible. These are only two of many examples of such breeding and selection in the many cultivars of hybrid daylilies that we know today, and many more examples exist in all domestically bred plants and animals.

This is the big difference between professional researchers and hobbyist breeders and researchers. The professionals are seeking proof, while the breeder is seeking results. The professional is seeking quantifiable, replicable proof through their research that can then be peer-reviewed (which is often a rather savage process), while the hobbyist breeder is seeking trends and results through their research and experimentation. That does not mean that the research and experimentation of hobbyists cannot be pursued in a scientific manner, using sound scientific principals. It simply means that hobbyist research is not of the standard to constitute proof in the modern, scientifically accepted sense. It does though, often, produce results. Both types of research, experimentation and breeding have their place, but they are not the same thing and it is important to be aware of that and to acknowledge the difference.