DEAR Jean-Pierre Jost

Greetings

You are right in your ststement given above.However I see your query in another context.

My thought says it is more true in the reverse sense.

i.e. When we are making selection of plants against biotic and abiotic factors, we loose the quality component to a greater extent.

Let me share one simple example in reference to Basmati rice in North India (specifically Punjab state).

Here, old basmari varieties (e.g Basmati 370 also VERNACULARLY called Pakistani basmati) were having wonderful quality characters such as aroma,elongation and many cooking related better indices .But is was prone to lodging with low yield.Through crop improvement, many varieties have come up which possess resistance/tolerance to biotic factors and yield is almost double along with dwarf stature.However, the grain quality indices as mentioned above and above all taste is not at par with Basmati 370.This is one case and their are many more like this.

Let us invite opinions on the subject.

Thank you Dr Singh for taking your time to give me an answer. I guess that the selection of the new varieties you mention was done by taking both biotic/abiotic resistance and yield into consideration rather than using only one parameter as criteria for selection. Or maybe resistance and yield were both genetically linked.

Rusticity of living organisms is developed to survive (and to give offspring) to particular stressful conditions. Camels are highly resistant to desert conditions; however, they aren't able to survive in Antarctic, for example. Genes establish complex relationships among them, thus, when a gene is selected, or not, it might affect the behavior and expression of the rest of genes, as a chain reaction. Nature "select" organisms to survive and to reproduce. Ancient human beings began to select those plants with bigger fruit, more tasted, with more yield.... in the way, most of rusticity genes were lost or silenced. Even, during Green Revolution the yield was emphasized over rusticity. The many characteristics are included in an improvement program, the higher the difficulties to succeed, especially when methods to create variation that affect to the whole genome are used, as crossing and mutations.

Thank you very much Ricardo for your answer. Does it means that wild plants living in the absence of challenges will gradually lose their ability to fight against diseases and pest? could it be an epigenetic phenomenon, like the methylation of CpGs of the promoters of resistance genes?

Dear Jean

We cannot rule out possibility of your querie in previous statement.However this can happen in both directions.This means even if a particular character is lost or diluted, under a given set of conditions, it might get strengthened when harsh or other set of conditions prevails.

This is my opinion.Let us invite more for wider understanding.

Dear Kulvir, I agree with you and one way to test this possibility could be a treatment of the plant with specific elicitors.

Dear Jean-Pierre,

Plants have both general and specific defense mechanisms, from mechanical barriers to molecular machineries. Plants are being challanged all the time, thus they're adapted to resist "normal" stresses, e. g. freezing temperatures during the night, high temperatures during the summer hot days... Plants don't have the possibilities to move like animals, therefore they have to resist in situ these normal stresses. However, under sudden not normal stresses (e. g. the burst of a new pathogen strain) they have to evolve to overcome them. As evolution is probably a gradual process, this suggest that plants have silent defense mechanisms that can act under the new environmental challange. Now it has been well documented the role of epigenetic on the expression of defense mechanisms in plants. See:

Luna, Estrella, and Jurriaan Ton. "The epigenetic machinery controlling transgenerational systemic acquired resistance." Plant signaling & behavior 7.6 (2012): 615-618.

Kind regards

Dear Ricardo thank you so much for your valuable comment and for the reference

Have a nice week end, best regards

jp

Your welcome. The same for you