Ploidy and sex expression in monoecious hop (Humulus lupulus)

Botany ◽  
2012 ◽  
Vol 90 (7) ◽  
pp. 617-626 ◽  
Author(s):  
Suzana Skof ◽  
Andreja Cerenak ◽  
Jernej Jakse ◽  
Borut Bohanec ◽  
Branka Javornik

Humulus lupulus L. is a dioecious perennial plant, cultivated for its female inflorescences. Spontaneously arising monoecious hop plants, carrying male and female flower types on a specific plant, occasionally occur in the progeny of certain hop crosses. We assessed the ploidy of 58 monoecious plants, progenies of various crosses of diploid parents, to provide additional data on hop monoeciousy. Flow cytometric analysis revealed that a high percentage (41.4%) were triploid. An inheritance analysis of parental alleles using six codominant SSR markers demonstrated a primarily paternal origin (84.2%) of unreduced gametes as the cause of triploidy in monoecious plants. All triploids had predominantly male flowers with a few female cones; this phenotype was found only within this ploidy group. All other monoecious plants were diploid, except for one genotype with the highest nuclear DNA content, which showed an aneuploidic number of chromosomes (21). Male hops showed the lowest nuclear DNA amount, as measured by DAPI and propidium iodide fluorochromes. The estimated AT frequency placed hop among species with a high AT content, which was slightly higher in male than in female plants (63.0% vs. 62.5%). The results are discussed in relation to the occurance of ploidy and sex expression in monoecious hop.

1999 ◽  
Vol 98 (8) ◽  
pp. 1344-1350 ◽  
Author(s):  
M. A. Lysák ◽  
M. Dolez˘elová ◽  
J. P. Horry ◽  
R. Swennen ◽  
J. Dolez˘el

2011 ◽  
Vol 83 (3) ◽  
pp. 993-1006 ◽  
Author(s):  
Patrícia M.O. Pierre ◽  
Saulo M. Sousa ◽  
Lisete C. Davide ◽  
Marco A. Machado ◽  
Lyderson F. Viccini

Cytogenetic analyses, of pollen viability, nuclear DNA content and RAPD markers were employed to study three chemotypes of Lippia alba (Mill.) (Verbenaceae) in order to understand the genetic variation among them. Different ploidy levels and mixoploid individuals were observed. This work comprises the first report of different chromosome numbers (cytotypes) in L. alba. The chromosome numbers of La2-carvone and La3-linalool chemotypes suggested that they are polyploids. Flow cytometric analysis showed an increase of nuclear DNA content that was not directly proportional to ploidy level variation. A cluster analysis based on RAPD markers revealed that La3-linalool shares genetic markers with La1-citral and La2-carvone. The analysis showed that the majority of genetic variation of La3-linalool could be a consequence of ixoploidy. ur data indicates that sexual reproduction aong those three chemotypes is unlikely and suggests the beginning of reproductive isolation. The results demonstrated that chromosome analysis, nuclear DNA content estimation and RAPD markers constitute excellent tools for detecting genetic variation among L. alba chemotypes.


Genome ◽  
2004 ◽  
Vol 47 (6) ◽  
pp. 1053-1060 ◽  
Author(s):  
Juan C Herrera ◽  
Marie C Combes ◽  
Hernando Cortina ◽  
Philippe Lashermes

Factors controlling gene introgression into cultivated arabica coffee (Coffea arabica L.) were investigated. Interspecific triploid hybrid plants between the tetraploid species C. arabica (2n = 44) and a diploid species (2n = 22), either Coffea canephora or Coffea eugenioides, were backcrossed to C. arabica (male parent). Flow cytometric analysis of the nuclear DNA content revealed that most of the BC1 individuals derived from triploid hybrids involving C. eugenioides were tetraploid or nearly tetraploid. Among the gametes produced by the interspecific triploid hybrids, those possessing approximately 22 chromosomes appeared strongly favored. The amount of introgression in BC1 individuals (21 and 43 for the BC1 progenies involving C. canephora and C. eugenioides, respectively) was estimated using species-specific microsatellite markers. A large number of introgressed markers was observed in all BC1 individuals. Nevertheless, while the frequency of introgressed markers seemed as expected, assuming random chromosome segregation and diploid gamete formation, in the BC1 derived from triploid hybrids involving C. canephora, this frequency appeared significantly lower in the BC1 derived from triploid hybrids involving C. eugenioides. Furthermore, the comparison of reciprocal progenies between C. arabica and triploid interspecific hybrids (C. arabica × C. canephora) used as male or female parent revealed a very strong effect of the backcross direction.Key words: irregular meiosis, coffee, reciprocal crosses, molecular marker, triploid hybrids.


Genome ◽  
1990 ◽  
Vol 33 (5) ◽  
pp. 659-662 ◽  
Author(s):  
H. L. Porter ◽  
A. Lane Rayburn

The B-chromosome and C-band numbers were determined in 12 Arizona Indian maize populations. These populations were originally collected from altitudes ranging from 100 to 5300 ft (1 ft = 0.3048 m). In addition, the total nuclear DNA amounts of these populations have been observed to vary by as much as 20%. The number of B-chromosomes was not significantly correlated with altitude, C-band number, or nuclear DNA amount. C-band number was significantly correlated with both altitude and genome size. It does not appear that the amount of C-band variation can account for the large nuclear DNA variation observed in these accessions. Additional A-chromosomal DNA sequences may be involved in the nuclear DNA content variation that exists among these accessions.Key words: heterochromatin, DNA content, evolution, repeated DNA.


1979 ◽  
Vol 27 (1) ◽  
pp. 520-521 ◽  
Author(s):  
E Sprenger ◽  
S Witte

Flow cytometric analysis of cytologic samples from four different organs shows that nuclear DNA content of malignant cell populations depends to a large extent on organ of origin of the tumor. This fact must be considered in planning screening systems.


1995 ◽  
Vol 24 (1) ◽  
pp. 44-47 ◽  
Author(s):  
Tohru Saito ◽  
Tomomi Yamashita ◽  
Ken-ichi Notani ◽  
Hiroshi Fukuda ◽  
Shigetaka Mizuno ◽  
...  

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 580e-580
Author(s):  
Rodomiro Ortiz ◽  
D.E. Costich ◽  
T.P. Meagher ◽  
N. Vorsa

DNA flow cytometry was used to determine nuclear DNA content in diploid blueberry species, and 3x, 4x, 5x, and 6x ploidy levels. Relative fluorescence intensity of stained nuclei measured by flow cytometry was a function of the number of chromosome sets (X): Y = 3.7X – 2.3 (r2 = 95.1%). DNA flow cytometry should be useful for ploidy level determination in the seedling stage. A significant linear relationship was established between nuclear DNA content and number of chromosomes (x); DNA (pg) = 0.52 x1 (r2 = 99.8%). Based on this equation the haploid genome DNA amount (1C) was calculated as 0.62 ± 0.08 pg, with an approximate haploid genome size of 602 Mbp/1C. The results indicate that conventional polyploid evolution occured in the section Cyanococcus, genus Vaccinium: the increase in DNA was concurrent with increase in chromosome number. DNA content differences among 2x species were correlated with Nei's genetic distance estimates based on 20 isozyme markers. Most of the variation was among species (49%), with 26% between populations within species, and 25% within populations.


HortScience ◽  
2005 ◽  
Vol 40 (6) ◽  
pp. 1763-1767 ◽  
Author(s):  
Ekaterina Papadopoulou ◽  
Rebecca Grumet

The Cucurbitaceae family is noted for a diversity of sex expression phenotypes. Typically, a phase of male flowers precedes either female or bisexual flower production. Sex determination of individual flowers is regulated by a combination of genetic, environmental, and hormonal factors. Ethylene, auxins, and gibberellins have all been shown to influence flower sex expression in cucurbits. Ethylene, which promotes femaleness, plays a predominant role. In this study, we tested whether brassinosteroids (BR), a more recently identified class of plant hormones, also influences cucurbit sex expression. Applied epi-brassinolide (epi-BL) caused a significant decrease in time of appearance of the first female flower on monoecious cucumber plants, and increased total female flowers on the main stem. Increasing concentrations had a stronger effect. Of the three species tested, cucumber, melon and zucchini, cucumber was the most responsive to BR. Application of epi-BL also caused an increase in ethylene production by cucumber and zucchini seedlings, suggesting that the BR effect may be mediated by ethylene. To investigate the possible relationship between BR and ethylene on sex expression, we identified the concentration of ethephon (5 ppm) that caused an increase in ethylene production comparable to that induced by 10 μm epi-BL (approximately two-fold). Treatment with 5 ppm ethephon was sufficient to increase femaleness of cucumber plants, but not zucchini plants, suggesting that the difference in response to epi-BL treatment may reflect differences in sensitivity to ethylene. Collectively, our results indicate that application of brassinosteroids to cucumber cause earlier and increased female flower production, and that the effects may be mediated, at least in part, by brassinosteroid-induced production of ethylene.


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