Determination of ploidy and nuclear DNA content in populations of Atriplex halimus (Chenopodiaceae) (original) (raw)
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Determination of Ploidy Level and Nuclear DNA Content in Tunisian Populations of Atriplex halimus L
Genetic Resources and Crop Evolution, 2006
15 Atriplex halimus L. (Chenopodiaceae) (Saltbush) is a perennial species used as a fodder shrub for livestock 16 in arid and semi-arid areas, particularly in North Africa. The aim of this work was to determine whether 17 differences in ploidy level and/or nuclear DNA content exist among populations from widely-separated 18 sites in Tunisia. We determined nuclear DNA content and chromosome numbers for populations of 19 A. halimus from seven different locations (Gabes, Medenine, Tataouine, Monastir, Tunis, Sidi Bouzid, 20 Kairouan). The chromosome counts showed that all the Tunisian populations, plus a population from 21 Eraclea (Italy), were tetraploid (2n = 4x = 36) whereas a population from Cala Tarida (Spain) was 22 diploid (2n = 2x = 18). With respect to nuclear DNA, the 2C DNA content of population Cala Tarida 23 was estimated to be 2.41 pg. There was no significant difference among the tetraploid populations (or 24 among plants within populations), whose 2C DNA content ranged from 4.92 to 4.97 pg.
Caryologia, 2008
Atriplex halimus L. is a perennial native shrub of the Mediterranean Basin with an excellent tolerance to drought and salinity. The aim of this work was to estimate nuclear DNA content in populations of A. halimus L. by flow cytometry, an efficient method to estimate ploidy levels and to determine nuclear DNA content in plants. Flow cytometry is a technique which permits rapid estimation of nuclear DNA content. Because of its speed, precision and convenience, this method of analysis of nuclear DNA content finds an enormous number of applications which cover basic research, breeding and production. The results obtained indicate that the technique might greatly simplify the analysis of plant genomes at the molecular level.
Chromosome numbers in Tunisian populations of Atriplex halimus L. (Chenopodiaceae)
2006
Atriplex halimus L. (Chenopodiaceae) can be divided in two subspecies: the diploid halimus (2n = 2x = 18) and the tetraploid schwainfurthii (2n = 4x = 36). This was based on differences in morphology, with respect to habit, size, leaf shape and fruit morphology. Chromosome numbers for 5 populations of A. halimus L. from Tunisia (Gabès, Kairouan, Monastir, Sidi Bouzid,
Plant Systematics and Evolution, 1999
Somatic chromosome numbers have been determined for the following Cerastium taxa: C. eriophorum (2n = 36), C. alpinum (2n = 72), C. transsylvanicum (2n = 108), C. arcticum (2n= 108), C. latifolium (2n=36), C. carinthiacum (2n = 36), C. banaticum (2n -36), C. arvense subsp, glandulosum (2n= 36), C. arvense subsp, arvense (2n --72) and C. fontanum (2n = 144). Karyotypes of three diploid species (C. eriophorum, C. banaticum and C. latifolium), belonging to three different taxonomic groups, were analysed and found to be similar. The relative nuclear DNA contents of all taxa were determined by flow cytometry and, for five species, also by Feulgen cytophotometry. The values obtained by the two methods are similar. A comparison of nuclear DNA contents among diploids shows that values differ significantly between different taxonomic groups, and are correlated with average chromosome size. Within closely related polyploid groups nuclear DNA amounts increase from 2x-to 4x-and 6x taxa as 1 : 1.4 : 2.4 in the C. alpinum complex, whereas DNA amounts are doubled comparing 2x-and 4x-subspecies in the C. arvense complex.
Caryologia, 2007
Atriplex halimus L. (Chenopodiaceae) can be divided in two subspecies: the diploid halimus (2n=2x=18) and the tetraploid schweinfurthii (2n=4x=36). This was based on differences in morphology, with respect to habit, size, leaf shape and fruit morphology. Atriplex halimus L. is a perennial shrub used as a fodder in the arid and semiarid parts of North Africa and the Middle East. A. halimus is dominant in the semi-arid and sub-humid areas while A. schweinfurthii is more common in arid areas. Natural populations of A. halimus L. exhibit large levels of plant morphological and physiological variability. However, little is known about the morphological variability of its fruits. We located and sampled ten populations of Atriplex halimus L. in Tunisia to assess their fruit diversity. Fruit shape, size, length, width, and weight, measured on samples collected from all ten populations, were highly variable suggested a height phenotypic variability in the natural populations of Atriplex halimus L. In another hand, chromosome numbers for five populations of Atriplex halimus L. from Tunisia were determined. Although the Tunisian populations originated from widely-separated sites of contrasting climatic conditions, the chromosome counts showed that all of them were tetraploid (2n = 4x = 36).
Male-Specific DNA in the Dioecious Species Atriplex garrettii (Chenopodiaceae
American Journal of Botany, 1998
The mechanism of sex determination in dioecious species of the genus Atriplex (Chenopodiaceae) has not been determined. This paper reports the discovery of a male-specific DNA fragment in the diploid dioecious species A. garrettii. DNA samples extracted individually from ten male and ten female plants were bulked by sex. Random amplified polymorphic DNA (RAPD) fragments were generated in the two bulks in order to identify markers that were polymorphic between male and female plants. A total of 158 decamer primers were tested. A 2075 base-pair (bp) male-specific DNA fragment generated with the OPAF-14 primer was identified. The fragment was cloned and partially sequenced and 24-mer primers that exclusively amplified this fragment were constructed. When 124 male plants, 126 female plants, and one hermaphroditic plant were tested individually, the male-specific 2075-bp DNA fragment was present in the hermaphrodite and all but one of the male plants, and was absent in all female plants. A smaller DNA fragment (ϳ1800 bp) that was homologous to the 2075bp fragment was amplified from the single male plant that lacked the 2075-bp fragment. Cytogenetic analysis revealed no apparent heteromorphic sex chromosomes. These observations suggest that sex determination in A. garrettii is genetic, with no evidence of heteromorphic sex chromosomes.
New chromosome numbers for plant taxa endemic to the Balearic Islands
Folia Geobotanica, 2006
Mitotic chromosome numbers are reported from 25 vascular plant taxa, endemic to the Balearic Islands that are poorly known cytogenetically. The chromosome numbers ofAnthyllis vulneraria subsp.balearica (2n=12),Cymbalaria fragilis (2n=56), andPolygonum romanum subsp.balearicum (2n=40) were determined for the first time. A new chromosome number was found in several populations ofAnthyllis hystrix (2n=70) suggesting that this species is decaploid, in contrast to an earlier work reporting a higher ploidy level (2n=12x=84). The new chromosome number 2n=32 was reported inHypericum hircinum subsp.cambessedesii. It is suggested that the previous count (2n=40) could be explained by the presence of anomalous pentaploid cells in some tissues, contrating with the presence of a regular tetraploid complement (2n=32). Cytogenetic observations suggest thatSibthorpia africana has a diploid chromosome complement of 2n=18, with 0–2 accessory chromosomes. Accessory chromosomes are also reported forPhlomis italica, being the first record of B chromosomes in this genus. Chromosomal instability was found inGalium crespianum andG. friedichii species, with three numbers 2n=44, 55 and 66. Two cytotypes differing in ploidy level were documented within single plants. It is suggested that both species share a regular complement of 2n=44 and that the past hybridization events and formation of regenerating roots from the typical rootstock ofG. crespianum andG. friedrichii could be involved in the genesis of chromosome variants through partial endopolyploidy and concomitant somatic segregation.
Plant Systematics and Evolution, 2012
The genome size of 265 plants and the GC content of 126 plants from 63 populations of the Cyanus triumfetti and Cyanus montanus groups, collected across the Carpathians, Pannonia, Bohemian Massif, and Western and Dinaric Alps were determined by PI and DAPI flow cytometry. Variation of the nuclear DNA content among homoploid species, and intraspecific and interpopulation variation were confirmed in simultaneous analyses. The 2C-value at the diploid level (the C. triumfetti group) varied from 2.53 for Cyanus dominii subsp. sokolensis to 3.06 pg for C. triumfetti s.s. (1.21-fold range). At the tetraploid level (the C. montanus group), the 2C-value varied from 5.19 for Cyanus mollis to 5.84 pg for C. montanus (1.13-fold range). High intraspecific and interpopulation variation in the amount of nuclear DNA in the C. triumfetti group correlates with the extensive morphological variation found in this group. Significant between-species differences in genome size indicate that this attribute may be used as a supportive taxonomic marker for both of the groups studied. The GC content varied by 2.93 %, from 39.46 % for ''Cyanus axillaris'' to 40.61 % for Cyanus adscendens; this character is of no value for taxonomic purposes. Genome size of the studied populations is significantly higher in southern parts of the distribution area and at higher elevations. Plants with smaller genomes tend to occur in dry areas at low altitudes with high diurnal and annual temperature oscillations. The GC content of the populations studied is significantly correlated with longitude, increasing from east to west; and plants with GC-rich genomes are concentrated in the coldest areas with low minimum temperatures. Keywords Base composition Á Cyanus triumfetti group Á Environmental conditions Á Flow cytometry Á Homoploid species Á Taxonomy Electronic supplementary material The online version of this article (