recurence from a single gene *non* expression..?...

Wandering on the web I found the followings with a common autor: Laurence HIBRAND SAINT OYANT that aim at a perpective:

New resources for studying the rose flowering process

Authors: Foucher, Fabrice; Chevalier, Michel; Corre, Christophe; Soufflet-Freslon, Vanessa; Legeai, Fabrice; Hibrand-Saint Oyant, Laurence

Source: Genome, Volume 51, Number 10, 1 October 2008 , pp. 827-837(11)

Abstract:

Knowledge of the flowering process - an important trait in ornamental plants such as roses - is necessary for efficient control of flowering. This study was carried out to develop and characterize new resources to gain further insight into floral control in rose. We studied floral initiation in a nonrecurrent blooming rose (hybrid of Rosa wichurana) and a recurrent blooming rose (Rosa hybrida Black Baccara

Hi Pierre,

This is great! Thank you for sharing these abstracts!! What a time of increased tools and ability to understand biochemical pathways. Those cDNA libraries and finding differentially expressed genes to help narrow in on what is happening is fantastic. It sounds like the things Andy Roberts and others proposed with GA in the late 1990’s in flowering of roses is being confirmed and built upon.

It’ll be fun to find ways to piece together these ideas and brainstorm new ways we as rose breeders will be able to utilize these discoveries in practical ways.

IMO giberellins are a secondary part as it is only a mediator matter.

Recurrence / non recurrence genetical control is the problem.

I put these abstracts together as contexts of the new informations in a popularizing article paragraf. In order to display some matters these scientists are working on.

They are considering that there is no repeat flowering genes and instead found one gene whose expression is supposed to hinder repeat flowering. Not unlike thoughts I had years ago.

It is a major change of perspectives. Then at species level it is the non recurrence control (NRC) that has variants from strong reliable in all environments with a short flowering to others allowing a longer flowering period and/or more or less rebloom eventually being fallible at least in some non native environments. These partial imperfect fallible or non existing NRC being primitive features.

It is notable that rugosa being the most recurrent species has some form of flowering control with delayed first flowering. Control of flowering if decisive/basic for genus is probably a relatively recent acquisition along roses evolution as it is variable and not allways strong. It is outbreedable.

First consequence is that recurrence appearance in cultivated roses likely was not through a rare mutation only. It was from early species hybrid seedlings imbalance just as some of us experienced. And probably occured many times in China where obviously many species contributed.

Second consequence is that when breeding from different species we do no longer need to inbred recurrence from a single origin. Only look for NRC gene non or lesser expression.

It is something I do with a lot of low recurrent species hybrids stemming only from larger growing species. Most without modern roses nor any of their ancestral species contribution.

If we knew the climate where Rosa first evolved (SE Asia most probably, since that is the region of the greatest diversity), then we could hypothesize that roses were first recurrent. Climate change, including glaciations (I know little of the phases in Asia but believe there was a period of at least 500,000 years, maybe 800,000), could explain the evolution of nonrecurrence as a adaptive mechanism: one that would maximize production of seed during a warm cycle and hasten dormancy as colder seasons approach.

Or…roses could have been annual plant, with the sole objective being the production of seed in season.

Another publication along the thesis (*** are mine):

Flowering Powers Genetic Understanding

ScienceDaily (Dec. 27, 2009)

"Turning off this gene triggers the plant’s flowering and reproductive phase, and the timing of this is crucial to the plant’s reproductive success. Many different signals integrate into FLC to either maintain or release its suppression of flowering. One of these signals is an extended period of cold that is essential for some plants to flower, a process known as vernalization. It ensures that flowering starts in the favourable conditions of spring after the cold of winter has passed.

“In response to cold, non-coding anti-sense transcripts covering the entire FLC gene act to silence FLC sense transcription. Once it has been turned off, or silenced, the gene retains the ‘memory’ of this for the rest of its life and remains silenced even after the cold stimulus has been removed.”

So hypothetically, the right combination of the presence/absence of the certain signals could explain why some Banksias and rambling cultivars flower continuously in cool, mild climates.