Cytogenetic variability and new chromosome number reports in Silene L. species (Sect. Lasiostemones, Caryophyllaceae)

Karyotype and meiotic studies were performed in 19 populations of five Silene species of the section Lasiostemones Boiss., growing in Iran. The species of S. longipetala, S. tenella, S. claviformis and S. Marschallii possessed 2n = 2x = 24 chromosome number, while S. propinqua populations were diploid and tetraploid with two different base number of x = 10 and 12 (2n = 4x = 40). The results obtained support the earlier report on S. Marschallii while the chromosome number of S. longipetala, S. tenella, S. claviformis and S. propinqua are new to science. The chromosomes were mainly metacentric and sub-metacentric. The species studied differed significantly in total size of the chromosomes, size of the short arms and the long arms, indicating the role of quantitative genomic changes in the Silene species diversification. They also differ in their karyotypic formulae indicating the occurrence of structural changes in their chromosomes. The Silene species were placed in 1A, 2A and 1B classes of Stebbins karyotype symmetry which are considered relatively primitive in this system. PCA ordination of the Silene species indicated karyotypic distinctness of the species studied. Meiotic analysis showed that Arak population of S. Marschalii forms quadrivalents due to the occurrence of heterozygote translocation between two pairs of chromosomes which in turn may increase the amount of genetic variability in the next generation. Unreduced pollen grains were formed in populations of S. Marschalii due to multipolar cell formation, while B-chromosomes were observed in some of the species studied

Correlation between geography and cytogenetic diversity in Pomegranate (Punica granatum L.) cultivars in Iran

Pomegranate (Punica granatum L.) is an important horticultural plant with several cultivated forms planted in different regions of Iran. Due to its economic importance, studies have been carried out to illustrate the genetic diversity at the chromosomal and molecular levels in different pomegranate cultivars growing in this region. This study analyzed chromosome pairing and B-chromosomes of 21 pomegranate cultivars and tried to investigate the effects of geographical parameters like altitude and longitude as well as elevation and the mean annual rainfall on cytogenetic diversity of these taxa. An ANOVA test revealed the presence of a significant difference for chiasmata and chromosome pairing among the cultivars, indicating their genetic differences. A positive significant correlation was observed between total chiasma frequency and terminal chiasmata, intercalary chiasmata and the mean number of quadrivalents. A significant positive correlation was observed between annual rainfall and the mean number of rod bivalents, while a significant negative correlation was found for the number of ring bivalents. Altitude did not show any correlation with the cytogenetic characters studied, but showed a significant negative correlation with the number of univalents. Longitude showed significant positive correlation with the number of ring bivalents and a negative correlation with the number of univalents and intercalary chiasmata. PCA analysis showed that both geographical and cytological features contribute greatly in the diversity observed in the pomegranate cultivars. The occurrence of multipolar cells and unreduced pollen grains were observed in some of the cultivars

Correlation between geography and cytogenetic diversity in Pomegranate (Punica granatum L.) cultivars in Iran Correlação entre a distribuição geográfica e diversidade citogenética de cultivares de romã (Punica granatum L.) no Irã

Pomegranate (Punica granatum L.) is an important horticultural plant with several cultivated forms planted in different regions of Iran. Due to its economic importance, studies have been carried out to illustrate the genetic diversity at the chromosomal and molecular levels in different pomegranate cultivars growing in this region. This study analyzed chromosome pairing and B-chromosomes of 21 pomegranate cultivars and tried to investigate the effects of geographical parameters like altitude and longitude as well as elevation and the mean annual rainfall on cytogenetic diversity of these taxa. An ANOVA test revealed the presence of a significant difference for chiasmata and chromosome pairing among the cultivars, indicating their genetic differences. A positive significant correlation was observed between total chiasma frequency and terminal chiasmata, intercalary chiasmata and the mean number of quadrivalents. A significant positive correlation was observed between annual rainfall and the mean number of rod bivalents, while a significant negative correlation was found for the number of ring bivalents. Altitude did not show any correlation with the cytogenetic characters studied, but showed a significant negative correlation with the number of univalents. Longitude showed significant positive correlation with the number of ring bivalents and a negative correlation with the number of univalents and intercalary chiasmata. PCA analysis showed that both geographical and cytological features contribute greatly in the diversity observed in the pomegranate cultivars. The occurrence of multipolar cells and unreduced pollen grains were observed in some of the cultivars.A romã (Punica granatum L.) é uma planta hortícola importante com diversas formas de cultura plantadas em diferentes regiões do Irã. Devido à sua importância econômica, alguns estudos genéticos têm sido realizados para ilustrar a diversidade genética em ambos os níveis cromossômico e molecular em diferentes cultivares de romã que crescem neste país. O presente estudo considera as análises de pareamento cromossômico e cromossomo-B em 21 cultivares de romã e tenta investigar os efeitos dos parâmetros geográficos, como altitude e longitude, bem como a elevação e a queda de chuva média anual sobre a diversidade citogenética destes cultivares. O teste ANOVA revelou a presença de uma diferença significativa para quiasmas e emparelhamento de cromossomos entre as cultivares, indicando a sua diversidade genética. A correlação positiva e significativa foi observada entre o freqüência total de quiamas de quiasmas terminais, quiasmas intercalares e o número médio de quadrivalentes. Uma correlação positiva foi observada entre a queda da chuva anual e o número médio de bivalentes haste, com correlação negativa significativa com o número de bivalentes anel. A altitude não mostrou qualquer correlação com caracteres citogenéticos estudados, enquanto a altitude apresentou correlação negativa significativa com o número de monovalentes. A longitude mostrou correlação positiva e significativa com o número de bivalentes anel e correlação negativa com o número de univalentes e chismata intercalares. A análise de PCA mostrou que tanto as características geográficas quanto citológicos podem contribuir grandemente na diversidade observada nas cultivares de romã. A ocorrência de células multipolares e grãos de pólen não reduzidos foram observados em alguns dos cultivares