Here is the explanation:
It could be that the Lavender plant that you treated with GA was not a true female (X/X) or that your early pear was not a true female (X/X)…
So in conclusion you ended up introducing a Xm/X allele in your project that is subject to hermaphrodism traits, therefore male inflorescence may be activated from environmental factors. It could be pretty easy to determine with strain introduced the Xm since you have lavender x lavender cross….
That subject was discussed in the (trick for controlling hormones on unstable strains) thread.
Here is some details:
The sexual phenotype of Cannabis often shows some flexibility leading to the differentiation of hermaphrodite flowers or bisexual inflorescences (monoecious phenotype). However this phenomenon is directly linked with both the plant genetic (chromosome), and the environmental condition. On an evolution point of view, the ability of a female plant to scent the absence of a male in its surrounding environment is not supported, since this evolution adaptation would have require the lack of male genetic in native plant population. Since sincemilla grow is new, on an evolution time scale, there would be no natural pressure for this new fitness phenomenon to appear as a new adaptation… Also, we should remember that Cannabis has a diploid genome (2n=20) with a karyotype composed of nine autosomes and a pair of sex chromosomes. A general belief suggest that Female plants are homogametic (XX) and male plants are heterogametic (XY). However, in these plants, sex expression is controlled by an X-to-autosome (X/A) balance system and not exclusively from the Y chromosome (confirmed from polyploidy essay)… The sex, is not determined by particular chromosomes, but by the genome assembly, and by the gene and chromosome interactions. All individuals are, in this manner, able to express one or the other sex. It was previously shown that sex expression also depends on different environmental factors and can be reversed by the application of plant growth regulators.
The following models were established:
- male plants with male inflorescence: X/Y, Xm/Y;
- male plants with female inflorescence, Xm/Xm;
- variable phenotypes, from true females to monoecious plants, but all with female inflorescence, Xm/X;
- female plants with inflorescence of female type, X/X
So if you get a clone only strain that may contain the Xm allele, you may end up with male inflorescence that may be activated from environmental factors…
So, in conclusion, if you don’t work with a true female X/X, you should pay good attention to the environmental stressor (light spectrum, plant density, temperature…etc) since all these variable will affect the predisposition of you plant to show intersex trait.
The Y chromosome will influence the sex determination of your plant, but the X\autosome ratio will also have an influence, specially with you female (hermaphrodite trait)...
Gender and Sexual Dimorphism in Flowering Plants, MONICA GEBER, Todd E. Dawson, Lynda Delph, Springer Science & Business Media, 6 déc. 2012 - 305 pages
Grant et al., 1994 concluded that the hemp has a sexual determinism based soon on X/autosomes equilibrium and not on a Y active mechanism.
Ainsworth, 2000 describes sex determination in the genus Cannabis as using "an X/autosome dosage-type.
Frankel and Galun, 1977 affirm that the males are X/Y, and the females are X/X. Besides that, the allele Xm exists, that determines the appearence of male flowers in female inflorescence. Thus, X/Xm plants have female inflorescence, but they can be not strictly females. Depending on genetic and non-genetic additional factors, these plants tend to masculinization, reason for which Kőhler named them “subgynoecious”. The Xm/Xm plants will have female inflorescence, but functionally are males. Considering the results obtained in various studies on polyploids by other researchers, Kőhler concluded that the masculinizing genes are autosomal and they are balanced by femaleness carrying genes of X chromosome, while the Y chromosome is “empty” under the aspect of sex determining genes.
An analogy could be made with Hop where polyploidy test confirmed the X\autosome relationship in sex determination:
Humulus lupulus possesses sex chromosomes. Female plants are homogametic with 2n¯18*XX, whereas male plants are heterogametic with either simple XY or multiple sex chromosome systems. Sex expression in hop appears to be regulated by an Xautosome balance system (Neve, 1961). This type of sex determination system is found in only two other genera, Cannabis and Rumex (Parker, 1990) and contrasts with the active Y-system found in some Silene species, in which the Y-chromosome speciﬁes maleness (Westergaard, 1946, 1958). A ratio of the number of X-chromosomes to the number of sets of autosomes of 0.5 gives rise to a male plant; a ratio of 1.0 gives a female, while intermediate ratios give rise to intersexual individuals.
Sexual development and sex chromosomes in hop, H. L. SHEPHARD", J. S. PARKER#, P. DARBY$ C. C. AINSWORTH"*
"Plant Molecular Biology Laboratory, Department of Biology, Imperial College at Wye, Wye, Ashford, Kent TN25 5AH, UK #University Botanic Garden, Cory Lodge, Bateman Street, Cambridge CB21JF, UK $Department of Hop Research, Horticulture Research International, Wye, Ashford, Kent TN25 5AH, UK
Received 28 April 2000; accepted 7 July 2000
The Y chromosome is “empty” under the aspect of sex determining genes:
The X/autosomes equilibrium is responsible for the sexual determination of Cannabis and the Y chromosome is not directly linked in the process. The mechanism involve the presence of activators genes on the X chromosome and negative regulation encoded by the autosomes. In simple words, positive elements to activate a female developmental pathway exist on the X chromosome and these are balanced by element that favor male developmental program located on the autosomes. That mean that with the lack of an X chromosome in a XY plant the positive elements produced by the solitary X chromosome won’t be sufficient to counteract the effect of suppressor encoded by the autosome and you will end up with a male plant.
If the sexual determination of Cannabis would be based on the Y active mechanism concept, how would it be possible to induce a male diploid plant (XY) to produce female flower?
(Induction of female flowers on male plants of Cannabis Sativa L. by 2-chloroethanephos-phonic acid, HYM Ram, VS Jaiswal - Cellular and Molecular Life Sciences, 1970 – Springer)
Ok, since the majority of scientific research are performed on hemp vs Marijuana, I just want to state that the sex linked genes expression in female Cannabis flower (Drug cultivar) are similar to the one in the diocious hemp. That been said…,
There are several excellent recent reviews of sex determination of diocious plant and cannabis genus. I would suggest:
Boys and Girls Come Out to Play: The Molecular Biology of Dioecious Plants, Charles Ainsworth, Ann Bot (2000) 86 (2): 211-221.
The regulation of sex determining gene as you refer to is similar to the regulation observed in Silene latifolio. However, Cannabis show a different type of regulation:
The increased length of the Y chromosome in hemp (Yamada 1943 cited by Sakamoto et al. 1995) suggests some similarity with the sex chromosomes of Silene latifolia (Sakamoto et al. 1998; Fig. 2.5). In this latter species, males have XY and females XX sex chromosomes (Dellaporta and Calderon-Urrea 1993). The structure of the Y chromosome is characterized by a non-pairing region including sex-determining loci and a pairing, pseudoautosomal, region which undergoes recombination with the X chromosome during meiosis. The non-pairing region of the Y chromosome contains female suppressing, male promoting and male fertility regions (Westergaard 1953 cited by Di Stilio et al. 1998; Charlesworth 2002). The sex determinism in Silene is based on an Y-active system, with dominant male factors and female suppressing factors mapping to the Y chromosome (Dellaporta and Calderon-Urrea 1993). In contrast, in hemp, the sex determinism is based on a X-to-autosomes system. In addition, the genetic basis of sex determinism in Silene is strong and shows little evidence for lability or environmental effects (Ainsworth 2000), while hemp displays a high plasticity of sexual phenotype.
Here is a good PhD thesis on the subject:
QUANTITATIVE APPROACH OF THE GENETIC DETERMINISM OF SEX EXPRESSION IN MONOECIOUS HEMP (CANNABIS SATIVA L.), AND ITS RELATIONSHIP WITH FLOWERING PHENOLOGY AND STEM AND SEED YIELDS
The sex determinism in dioecious hemp would be based on an X-to autosomes equilibrium and not on a Y-active mechanism (Westergaard 1958; Ainsworth 2000). This assumption agrees with the experiences carried out on polyploid hemp individuals (Warmke and Davidson 1944).
The X-to-autosomes system of sex determination is based on the ratio of the number of X chromosomes to the ploidy level. This system can explain why hemp polyploid individuals with XXY and XXXY formulae are female or female-hermaphrodite, and XY, XXYY and XYY individuals are male (Warmke and Davidson 1944).
The Y chromosomes are not necessary for the production of male flowers; moreover, the pollen can mature and be viable in the absence of Y chromosome.
The diversity of intersexual forms, the bipotency of sexually predetermined plants and the occurrence of fertile male flowers on female plants of dioecious hemp suggested that the sex in hemp would be determined by the activity of genes that are located not only on the sex chromosomes but also on the autosomes (Grisko 1937 cited by Truta et al., 2007; Sengbusch, 1952 cited by Westergaard, 1958; Rath, 1968 cited by Truta et al., 2007; Migail, 1986 cited by Mandolino and Ranalli, 2002). Grişko (1937 cited by Truta et al. 2007) considers that the determinants of phenotype and those of sexualisation are independent since female plants are able to produce male flowers under given environmental conditions. The ability to reverse the sex determination mechanism by hormonal treatment suggested that sex determination genes could regulate alternative programs of sexuality through a signal transduction mechanism that modifies endogenous hormonal levels (Dellaporta and Calderon-Urrea 1993).
Markers, referred to as MADC, for male-associated DNA sequence in C. sativa:
Hybridization of DNA from male and female plants by southern blotting analysis revealed either the absence of no sex-linked polymorphism (Mandolino et al. 1999), either multiple bands among which only few are male-specific (Sakamoto et al. 2000; Torjek et al. 2002; Sakamoto et al. 2005). Similarly, the in situ hybridization of chromosomes with the MADC3 and MADC4 sequences produced signals dispersed on all chromosomes and thus not specific of the Y chromosome. Thus multiple sequences encoding retrotransposable elements should exist ubiquitously in the genome of C. sativa (Sakamoto et al. 2005). This appears in agreement with the view of Clark et al. (1993), who observed no major difference in the distribution of repeated DNA sequences between X, Y and autosomes in Rumex acetosa, a dioecious species with heteromorphic sex chromosomes. According to Charlesworth (2002), the abundances in repeated DNA in plants bearing sex chromosomes would be mostly similar on both sex chromosomes and autosomes.