Re: Re: Epigenome genetics

I've looked at at some of the information on epigenome genetics. Basically it refers to the effects of environment on expression or non expression of certain genetic characteristics.
Vernalisation is an example of this. Exposure to low temperatures for a certain time ( temp and duration varies for cultivars and species) results in a permanent change in plant, enabling or increasing ability and speed of flowering. This way the environment changing the genetics. It can be turned off by bio-chemical response (speculation) from blooming parent rhizome. The specific condition is turned on and off regularly. this turning off and on does not result in any change in genetics or epigenetics of plant. Just the current condition of the plant.
The same is true of any changes from acclimatization. The plant can be sent back to original garden, grown for a couple of years and be sent back, have to go through acclimatization . This can be done forever and ther is no change to the genetics and epigentic composition. The plant still responds the same way, set and reset.. It doesn't matter what the condition of plant is when it sets seed. the inheritance of genes and epigenes will proceed the same . Any effects of epigentics will continue to set and reset regardless of initial stage, according to prevailing conditions. For example plant will be in bloom readiness when vernalized and not ready when vernalized. (of course I'm referring to oncers, spring only)
The Study showing inherited change refers to the change that was induced by chemical trauma (demethayliation) and not to any change induced by epigenetic condition at seed set. That is the change was induced by the chemical and was inherited as the change occurred to DNA.
Another example of inherited chemical change is my iris 'Canadian Streaker', a variegated foliage plant. It was produced by spraying some abandoned seedlings in a weed patch with roundup. This modified the plastids and can be inherited through maternal inheritance. Chemicals are often used to produce mutations, this was one of them.
Basically, there is nothing to support the idea (at this time) that there would be anything different from inheritance of seeds under different conditions. There may be some changes of seed viability caused by maternal effects, but this is a different situation. Maternal effect is the ability of the seed to germinate and grow based on energy contained in seed embryo. A plant that is acclimatised would naturally have more energy in embryo then one that is not properly acclimatized.
( Paul, any of your experiments would need to account and control for maternal effects)
The opposite is also true. Any rhizome that comes in from another climate could be more hardy the first summer in the garden and weaker after that. This is because plant comes in with energy obtained from where it was grown. Many plants from Oregon do well here the first summer (with their store of energy) but not afterward. Sort of reverse acclimatization . One good example of this is 'Isn't This something' Every couple of years I order some plants in to use for breeding. The first summer here it produces lovely blooms and bloom stalks. But never again. After that they are wimpy plants that barely survive and eventually fade away. Sometimes producing a few sparse blooms in second summer.
The length of summer , degree days, warmth of summer , day and night temperatures etc. all effect the storage of energy and setting of flower bud differentiation. New climate, new conditions, new plant response. 

Chuck Chapman

---------------------------------------------------------------------
To sign-off this list, send email to majordomo@hort.net with the
message text UNSUBSCRIBE IRIS
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index