Props to everyone for keeping it academic and civil! I hate it when these threads turn into a pissing match.
This just in (well 1999) and its GOOD Identification of DNA markers linked to the male sex in dioecious hemp (Cannabis sativa L.) G. Mandolino,A. Carboni,S. Forapani,V. Faeti,P. Ranalli A 400-bp RAPD marker generated by a primer of random decamer sequence has been found associated with the male sex phenotype in 14 dioecious cultivars and accessions of hemp (Cannabis sativa L.). The primer OPA8 generates a set of bands, most of which polymorphic among all the individual plants tested, and 1 of which, named OPA8400, present in all male plants and absent in female plants. A screening of 167 plants belonging to different genotypes for the association of the OPA8400 marker with the sex phenotype revealed that only in 3 cases was the 400-bp band was present in plants phenotypically female; on the contrary, in male plants the band was never missing, while in monoecious plants it was never present. Despite this sex-specific association, the sequences corresponding to OPA8400 were present in both staminate and carpellate plants, as revealed by Southern blotting and hybridization with the cloned RAPD band. The RAPD marker was sequenced, and specific primers were constructed. These primers generated, on the same genotypes used for RAPD analysis, a SCAR marker 390 bp in length and male-specific. This SCAR is suitable for a precise, early and rapid identification of male plants during breeding programs of dioecious and monoecious hemp. The main point is they found a DNA marker that all males have, an occasional female has (3 per 167) and hermies don't have. This creates a technique for finding males without spouting them (from micro propagation for instance). For us, This is pretty clear evidence that males and hermies are not created by the same genes. I'm gonna go out on a limb here and say the Males come from male DNA (on the marker they found) and hermies from ancient emergency DNA buried deep inside its chromosome. Nothing is ever this simple...many more markers will likely be found but its better than relying on an 80 year old publication. Marker = factor, factor does not = gene like I said earlier, but genes are contained on the marker. A marker is bigger than a gene (several or lots of genes).
Lets complicate it a little more. This is not cannabis specific but cites the above research on DNA markers. It appears male and female sterility factors also play a role. This may explain the strains that hermie but don't ever pollinate anything (or only make a few seeds per 1000 watts) Also the rare recombination might facilitate the segregation of a collection onto the female chromosomes. Plant sex determination and sex chromosomes D Charlesworth1 Sex determination systems in plants have evolved many times from hermaphroditic ancestors (including monoecious plants with separate male and female flowers on the same individual), and sex chromosome systems have arisen several times in flowering plant evolution. Consistent with theoretical models for the evolutionary transition from hermaphroditism to monoecy, multiple sex determining genes are involved, including male-sterility and female-sterility factors. The requirement that recombination should be rare between these different loci is probably the chief reason for the genetic degeneration of Y chromosomes. Theories for Y chromosome degeneration are reviewed in the light of recent results from genes on plant sex chromosomes. None of this relates to nutrient manipulation, but It does not appear that the scientific community has payed much attention to nutrient specific responses.
Sorry to bombard everyone with all this literature but that other post claimed to be the "almost final word" and then posted 20% of an 80 year old article. I am finding a ton of stuff and I find it fascinating. I hope someone else also cares. The role of roots in sex expression in hemp plants M. Kh. Chailakhyan,V. N. Khryanin When the shoots of young hemp (Cannabis sativa L.) plants were cut off the roots, cultured as cuttings, and regenerating (adventitious) roots were removed as soon as appearing, ca. 80–90% of the plants became male (had staminate flowers) whereas if the roots were allowed to develop a similar percentage became female (pistillate flowers). Treatment of de-rooted cuttings with 6-benzylaminopurine (15 mg/l) restored the percent of female plants to ca. 80. It is suggested that the root system plays an essential role in sex expression in hemp and that this role is related to cytokinin synthesis in the root. This may be more important than any of the other info! They made nearly feminized plants from tortured sprout cuttings. Doing this would kinda violate my theory about trying to cull out the male traits but it may also be INCREDIBLY useful and the male inducing method could be used to find SUPER stable moms. ????
This one compliments the last one perfectly. I'm gonna have to do an experiment! Genetic and hormonal regulation of growth, flowering, and sex expression in plants MK Chailakhyan - American Journal of Botany, 1979 Abstract: The interaction of the genetic and hormonal regulation of growth, flowering, and sex expression in plants is discussed. The genetic control of these processes is characterized, and data on their hormonal regulation are supplied. The interaction of genetic and hormonal regulation is considered with reference to tall-growing and genetic dwarf forms of the pea and wheat plants. It is shown that in the dwarf forms of the pea plant and in many other varieties, growth stimulation in response to treatment with the phytohormone gibberellic acid is clearly manifested and the expression of genetic dwarfism is eliminated, whereas in dwarf wheats it is expressed only slightly, if at all. At the same time both tall-growing and dwarf forms of both pea and wheat show a clearly defined growth retardation response to treatment with the growth inhibitor, abscisic acid, which causes the expression of physiological dwarfism. The short- and long-day characteristics of the photoperiodic response of plants are described as genetically controlled features, and data are given on the induction of flowering of a long-day variety coneflower grown under short-day conditions with the aid of gibberellins extracted from leaves of long-day vegetative plants of short-day Mammoth tobacco Data are also supplied on the induction of flowering of a short-day variety, red-leaved goosefoot, grown under continuous light with the aid of metabolites extracted from leaves of the same Mammoth tobacco plants flowering under short-day conditions. This demonstrates the possibility of hormonal regulation of the genetically controlled long-day and short-day characteristics in photoperiodically sensitive plants. Genetic and hormonal regulation of sex expression in two dioecious plants, hemp and spinach, is discussed. It is shown that sex expression in these plants is regulated by gibberellins which are synthesized in leaves and cause male sex expression and by cytokinins which are synthesized in the roots and cause female sex expression. These data indicate that sex expression in dioecious plants is the result of interaction between the genetic apparatus and phytohormones.
Nice thread. This stuff is really interesting. Sometime in the past I remember hearing or reading that when germinating cannabis seeds it was important to use a pot that was at least 5" deep. This was to prevent the long tap root from bending too much at the bottom of the pot, which supposedly caused hormonal changes in the plant resulting in higher male germination rates. The report you posted seems to confirm this, no?