I was going to say, which landraces are we supposed to be relying on? I'm still looking, but I'm only expecting to find remnants of past glories. Not much of the genetics of modern seed companies comes from contemporary landraces. That's because they are largely eradicated.
N.
Thats just my point Nevil, if they are all gone then what we ALL have left is a mixed pool of genes and lets not forget 40-60 years ago most not all cannabis was monoecious and look how far it has come in the period from 1960-1990 long before fems were around, thats when the landraces were lost not in the last 20 years. I think what were seeing here is the evolution and a fast evolution at that. What were you not suposed to start your seed sales back in the day Nevil? And looking back you spread hybrids all over the planet..right.??? Maybe some of your hybrids ruined a good landrace or two? Was this good or bad for the evolution? Was it good or bad for DJ to work 1000's of plants at a time to remove herms from the gene pool. You early pioneers set the controles for everything that is today...Some will produce fems and get a bad wrap, others will do it right and never have problems, and always some will hate. Hate is always a bad thing. understanding, compromise and most of all education. There are good fem seeds and there are fem seeds that should never be produced. Educating people on why and how are very important. I see seed companys even now bragging on how there seeds are mostly female because there produced by only "late nanners" these are the folks who need to be educated. There are always going to be "bad or good" practices in breeding, and we can all be more educated because the science is always changing..
There are many things which are upcomming and some maybe more wicked than just fems... What do you think its all going to stop there? No just take a look at this... what will this do when it is as easy as making a batch of fem seeds...
Take just a second and read this below... in five years or so this may be just a previlant as fems... its coming and its so easy.
Sciencedaily Reports.....
A reliable method for producing plants that carry genetic material from only one of their parents has been discovered by plant biologists at UC Davis. The technique, to be published March 25 in the journal Nature, could dramatically speed up the breeding of crop plants for desirable traits.
The discovery came out of a chance observation in the lab that could easily have been written off as an error.
"We were doing completely 'blue skies' research, and we discovered something that is immediately useful," said Simon Chan, assistant professor of plant biology at UC Davis and co-author on the paper.
Like most organisms that reproduce through sex, plants have paired chromosomes, with each parent contributing one chromosome to each pair. Plants and animals with paired chromosomes are called diploid. Their eggs and sperm are haploid, containing only one chromosome from each pair.
Plant breeders want to produce plants that are homozygous -- that carry the same trait on both chromosomes. When such plants are bred, they will pass the trait, such as pest resistance, fruit flavor or drought tolerance, to all of their offspring. But to achieve this, plants usually have to be inbred for several generations to make a plant that will "breed true."
The idea of making a haploid plant with chromosomes from only one parent has been around for decades, Chan said. Haploid plants are immediately homozygous, because they contain only one version of every gene. This produces true-breeding lines instantly, cutting out generations of inbreeding.
Existing techniques to make haploid plants are complicated, require expensive tissue culture and finicky growing conditions for different varieties, and only work with some crop species or varieties. The new method discovered by Chan and postdoctoral scholar Ravi Maruthachalam should work in any plant and does not require tissue culture.
Ravi and Chan were studying a protein called CENH3 in the laboratory plant Arabidopsis thaliana. CENH3 belongs to a group of proteins called histones, which package DNA into chromosomes. Among the histones, CENH3 is found only in the centromere, the part of the chromosome that controls how it is passed to the next generation.
When cells divide, microscopic fibers spread from each end of the cell and attach at the centromeres, then pull the chromosomes apart into new cells. That makes CENH3 essential for life.
Ravi had prepared a modified version of CENH3 tagged with a fluorescent protein, and was trying to breed the genetically modified plants with regular Arabidopsis. According to theory, the cross should have produced offspring containing one mutant gene (from the mother) and one normal gene (from the father). Instead, he got only plants with the normal gene.
"At first we threw them away," Chan said. Then it happened again.
Ravi, who has a master's degree in plant breeding, looked at the plants again and realized that the offspring had only five chromosomes instead of 10, and all from the same parent.
The plants appear to have gone through a process called genome elimination, Chan said. When plants from two different but related species are bred, chromosomes from one of the parents are sometimes eliminated.
Genome elimination is already used to make haploid plants in a few species such as maize and barley. But the new method should be much more widely applicable, Ravi said, because unlike the process for maize and barley, its molecular basis is firmly understood.
"We should be able to create haploid-inducing lines in any crop plant," Ravi said. Once the haploid-inducing lines are created, the technique is easy to use and requires no tissue culture -- breeders could start with seeds. The method would also be useful for scientists trying to study genes in plants, by making it faster to breed genetically pure lines.
After eliminating half the chromosomes, Chan and Ravi had to stimulate the plants to double their remaining chromosomes so that they would have the correct diploid number. Plants with the haploid number of chromosomes are sterile.
The research also casts some interesting light on how species form in plants. CENH3 plays the same crucial role in cell division in all plants and animals. Usually, such important genes are highly conserved -- their DNA is very similar from yeast to whales. But instead, CENH3 is among the fastest-evolving sequences in the genome.
"It may be that centromere differences create barriers to breeding between species," Chan said. Ravi and Chan plan to test this idea by crossing closely-related species.
The work was supported by a grant from the Hellman Family Foundation.
Source:
http://www.sciencedaily.com/releases...0324142012.htm