Breeding for disease resistance

A great deal of research has been going on aimed at breeding for disease resistance in roses. Here’s a 2008 paper that discusses powdery mildew resistance in R. roxburghii.

Qiang Xu, Xiaopeng Wen and Xiuxin Deng

Genomic organization, rapid evolution and meiotic instability of NBS-encoding genes in a new fruit crop

“Rolling the genetic dice frequently while applying high disease selection pressure is the way to go”

No doubt true, but each of us only gets to roll the dice so many times.

This certainly accords with what I am learning from my experiences. It seems reasonable to assume from this that integrating the best genes of existing rose material with new specie genetic material while not spraying would only serve to improve the gene pool the fastest. Anyway, this is the path I have chosen-doesn’t mean I have to stick with it if something better comes along, but I hate to hear that some wish to abandon all that others have done to date by starting over from just species.

My opinion is that we can assume that closely related disease susceptible parents will allmost always give disease susceptible offspring. Or easily broken down temporary resistance.

Now we know that host plants and pathogens coevolute. Ample number of closely related host plants call for a specialized pathogen cortege. Thats how vertical resistance is often broken down. At this point my opinion is that more than probably, many roses deseases were historically favored and virulence triggered by high consanguinity of Fortune Double Yellow progenies allmost all modern roses were and are still.

Rolling the dice has any worth only if we stay close enough to resistant species so that resistance is carried over as well as indispensable for its expression genetical environment.

“…that disease resistance in plants develops quickly and relies in on genetic recombination from generation to generation.” is in a given species context. This quite outstanding species developped this mostly within species competitive hability over millenaries. That it is evidenced in a rather remote from other roses not very successful species is probably no coincidence.

That this kind of genetical adaptability is possible to introgress, accumulate or combine with others is definitely still to be demonstrated. We too often are backcrossing to mainstream. It is no coincidence either how much so many resistant vars fail to confer this quality to progenies.

“Now we know that host plants and pathogens coevolute.”

It was a bit obvious since time and space move dynamically as one. It seems impossible for this not happen, especially since plants asexual abilities far outpace that of animals. It actually amazes me that it took this long to have solid proof, although I assume many scientists previously assumed it was valid. Similar could be said of medical science. Maybe we needed alll of the seemingly random idea to develop even a glimpse of holism.

Jackie, I do agree with you. Progress requires us to pull from all directions. Its overwhelming to think of and noarrow down all that is possible, especially since a lot of strides, as well as failures, have been made each decade.