.... cont'd
Now, here's some meat for you Nevil. There is a good amount of meat in the refs already posted. I would suggest checking them out before dismissing the claims presented therein.
Your welcome, Nevil- you don't need to thank me... but perhaps you could respect the fact that I have other pressing matters in my life, and can't be online 24/7 as some of your finer members, and afford me some degree of patience.
Almost ALL females I have come across can be induced to produce some amount of pollen via the use of GA3 (the gibberellin pathway) or via ethylene inhibitors (the ethylene pathway). I too have encountered oddballs, with (what I assume are) genetic mutations in specific genes involved in the shedding of pollen (dehiscence)... perhaps what has been referred to in this thread as 'sterility mutations'... which is an incredibly broad and IMO not a very useful term, other than to indicate "somethings going on". You see there are literally dozens, if not hundreds of genes that act in concert to produce what we see as 'pollen' at the end of flowering. Specific gene regulators turn genetic switches on and off to promote the cells to undergo meiosis, cellular division and gamete formation, the production of anthers, the internal production of pollen, production and regulation flavanoids that allow the chemical signaling for pollen to germinate on stigmas that are recognized as 'the same species'. These are very complex yet well demonstrated genetic pathways that exist, and allow pollen of a species to germinate on the stigma of a con specific (a member of the same species). Because there are some many genes involved in the process, there is a lot of room for error...a problem in one gene may completely disrupt the pathway, and lead to a deficiency in pollen production. What's interesting, an probably obvious to anyone that A) understands evolution and B) appreciates the impact of flaws in these genes... any non-functional copies of the genes would impact (ie negate) the ability of the individual with these genes to leave offspring. (This isn't entirely true because all outrossers can mask the genes and pass them along via carriers, with only homozygous recessive individuals showing the deficit... and therefor not contributing to the next generation.. the point being that these genes won't be completely purged from the population, and can still 'pop-up' in the form of males that can't produce pollen, or even females that can't produce pollen. To say these plants can;t exist would be foolish, they certainly do... especially in further generations or tightly bred (ie inbred) lines. However, the fact that these genes are highly conserved from one species to another (ie almost all flowering plants have versions of these genes) shows that they promote high fecundity (high fertility) and confer a high level of fitness (ability to leave offspring) to those who possess them.
I too have come across plants that are 'resistant' to switching sex... they will produce anthers, but no pollen will fly on heir own. Some plants must be beaten with sticks to force them to shed the pollen inside... but baring a rare mutation, almost all females are able to produce pollen.
Please remember Mendel's Second law of Inheritance- Independent assortment of characters. 'Gender' is a separate trait from 'intersexualty'. You can have female intersex plants and you can have male intersex plants, just like you can have 'pure' male and female plants (ie no flowers of the opposite sex under healthy environmental conditions).
Only MALE intersex plants show the MADC marker. Intersexuality is a completely different trait.. apparently autosomal in nature. Any genetic trait will have a marker, we just haven't identified the intersex marker(s) yet'
That is a question nobody can currently answer. However, there are mounds of evidence that any grower can suggest....fluctuating pH, light stresses... sever plant mutilation (heavy pruning during flowering)... there are a whole host of environmental effects we as growers try to avoid in our environment. Outdoors and greenhouse growers are less likely to induce these stresses being in a natural environment (baring soil/watering issues), which in my opinion is why we see less intersex plants in greenhouses or outdoors. We do know that stresses cause alterations in Ethylene levels within the plant- and we know that interfering with the ethylene pathway can alter sexual expression. Some stresses also alter Gibberellin levels, and we know application of exogenous Gibberellin-like molecules (like GA3) can induce male flowers on females (this is all well documented in other species if you care to look). I can't tell you for sure what mechanisms cause what, because cannabis research has been stifled for decades, and this type of question has not been adequately addressed by the scientific community.... hopefully over the coming years this will change... and the fact that Mandolino, Rinalli and Carboni and others in the Italian group along with Sakamoto and others in Japan are continually publishing new genetic works in Cannabis seems to support this claim. I would suggest many fruits are yet to be harvested in this regard, so we'll see what the future brings.
-Chimera
Now, here's some meat for you Nevil. There is a good amount of meat in the refs already posted. I would suggest checking them out before dismissing the claims presented therein.
Your welcome, Nevil- you don't need to thank me... but perhaps you could respect the fact that I have other pressing matters in my life, and can't be online 24/7 as some of your finer members, and afford me some degree of patience.
Almost ALL females I have come across can be induced to produce some amount of pollen via the use of GA3 (the gibberellin pathway) or via ethylene inhibitors (the ethylene pathway). I too have encountered oddballs, with (what I assume are) genetic mutations in specific genes involved in the shedding of pollen (dehiscence)... perhaps what has been referred to in this thread as 'sterility mutations'... which is an incredibly broad and IMO not a very useful term, other than to indicate "somethings going on". You see there are literally dozens, if not hundreds of genes that act in concert to produce what we see as 'pollen' at the end of flowering. Specific gene regulators turn genetic switches on and off to promote the cells to undergo meiosis, cellular division and gamete formation, the production of anthers, the internal production of pollen, production and regulation flavanoids that allow the chemical signaling for pollen to germinate on stigmas that are recognized as 'the same species'. These are very complex yet well demonstrated genetic pathways that exist, and allow pollen of a species to germinate on the stigma of a con specific (a member of the same species). Because there are some many genes involved in the process, there is a lot of room for error...a problem in one gene may completely disrupt the pathway, and lead to a deficiency in pollen production. What's interesting, an probably obvious to anyone that A) understands evolution and B) appreciates the impact of flaws in these genes... any non-functional copies of the genes would impact (ie negate) the ability of the individual with these genes to leave offspring. (This isn't entirely true because all outrossers can mask the genes and pass them along via carriers, with only homozygous recessive individuals showing the deficit... and therefor not contributing to the next generation.. the point being that these genes won't be completely purged from the population, and can still 'pop-up' in the form of males that can't produce pollen, or even females that can't produce pollen. To say these plants can;t exist would be foolish, they certainly do... especially in further generations or tightly bred (ie inbred) lines. However, the fact that these genes are highly conserved from one species to another (ie almost all flowering plants have versions of these genes) shows that they promote high fecundity (high fertility) and confer a high level of fitness (ability to leave offspring) to those who possess them.
I too have come across plants that are 'resistant' to switching sex... they will produce anthers, but no pollen will fly on heir own. Some plants must be beaten with sticks to force them to shed the pollen inside... but baring a rare mutation, almost all females are able to produce pollen.
Please remember Mendel's Second law of Inheritance- Independent assortment of characters. 'Gender' is a separate trait from 'intersexualty'. You can have female intersex plants and you can have male intersex plants, just like you can have 'pure' male and female plants (ie no flowers of the opposite sex under healthy environmental conditions).
Only MALE intersex plants show the MADC marker. Intersexuality is a completely different trait.. apparently autosomal in nature. Any genetic trait will have a marker, we just haven't identified the intersex marker(s) yet'
That is a question nobody can currently answer. However, there are mounds of evidence that any grower can suggest....fluctuating pH, light stresses... sever plant mutilation (heavy pruning during flowering)... there are a whole host of environmental effects we as growers try to avoid in our environment. Outdoors and greenhouse growers are less likely to induce these stresses being in a natural environment (baring soil/watering issues), which in my opinion is why we see less intersex plants in greenhouses or outdoors. We do know that stresses cause alterations in Ethylene levels within the plant- and we know that interfering with the ethylene pathway can alter sexual expression. Some stresses also alter Gibberellin levels, and we know application of exogenous Gibberellin-like molecules (like GA3) can induce male flowers on females (this is all well documented in other species if you care to look). I can't tell you for sure what mechanisms cause what, because cannabis research has been stifled for decades, and this type of question has not been adequately addressed by the scientific community.... hopefully over the coming years this will change... and the fact that Mandolino, Rinalli and Carboni and others in the Italian group along with Sakamoto and others in Japan are continually publishing new genetic works in Cannabis seems to support this claim. I would suggest many fruits are yet to be harvested in this regard, so we'll see what the future brings.
-Chimera
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Hey, isnt that the same thread both GreenintheThumb and Kopite can be found in Chimera? (Knock me over with a feather). 
,,,
