Cytological study the genusArenariaL. (Caryophyllaceae)

Abstract

-Karyotype and meiotic studies were performed in 16 populations of seven Arenaria species growing in Iran. All the species studied showed 2n = 2x = 22 chromosome number supporting the earlier report on A. persica, A. insignis and A. gypsophiloides while the chromosome numbers of A. polycnemifolia, A. zargariana, A. szowitsii and A. minutissima are new to science. The chromosomes were mainly metacentric and submetacentric. The species studied differed signifi cantly in total size of the chromosomes, size of the short arms and the long arms, indicating the role of quantitative genomic changes in the Arenaria species diversifi cation. They also differed in their karyotype formulae indicating the occurrence of structural changes in their chromosomes. Meiotic analysis showed quadrivalent formation in Moorchegan population of A. persica and Kandovan population of A. insignis possibly 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. Cytomixis led to the formation of unreduced pollen grains in Mishoodagh population of A. gypsophiloides var. glabra, while B-chromosomes were observed in A. insignis and A. polycnemifolia species.

Meiotic Studies in 14 Species of the Nepeta L. (Lamiaceae) From Cold Desert Regions of Lahaul-Spiti and Adjoining Areas of Northwest-Himalaya, India

“…Low pollen viability and heterogenous size of pollens in one of the population of N. discolor Royle ex Benth. from the Koksar population (PUN54163) reflects the role of meiotic abnormalities especially laggards, bridges stickiness of chromosomes and cytomixis as suggested by Singhal et al (2008) and Fatemeh et al (2010). However, the influence of environmental factors (Jones andNewell 1948, Kurtz andLiverman 1958), nutrition (Bell 1959), ploidy (Gould 1957, Kapadia andGould 1964) and geographical variation (Cain and Cain 1944) on pollen size and fertility in flowering plants should not be underestimated.…”

Studies on Male Meiosis and Microsporogenesis in <i>Rumex dentatus</i> L., an Important Medicinal Plant of North Western Himalaya

“…Such genetic differences have earlier been reported in different plant species by Baptista-Giacomelli et al (2000). According to Fadaei et al (2010), Saggoo and Farooq (2011), Kumar et al (2012) and Jeelani et al (2012Jeelani et al ( , 2014Jeelani et al ( , 2015, and cytomixis results in the production of unreduced gametes in several angiosperms or leads to the production of aneuploid plants. The formation of unreduced gametes is of evolutionary significance in a way that it can lead to the production of plants with higher ploidy level through polyploidization (Villeux 1985).…”

“…Chromatin stickiness involving few bivalents or whole complement was seen from prophase-I to metaphase-I. Cytomixis and chromatin stickiness are considered to be the result of genetic factors (Fadaei et al 2010) and environmental factors (Nirmala and Rao 1996) as well as genomic-environmental interaction (Baptista-Giacomelli et al 2000) and seems to be equally applicable to the presently investigated populations. There seems to be a positive correlation between the pollen and stomatal size with the level of ploidy.…”

Consequences of colchicine induced intermeiocyte connections inHelianthus annuus

“…However, other environmental and physiological processes also alter cytomixis (Bellucci et al 2003;Boldrinia and Pagliarini 2006;Lattoo et al 2006). Fatemah et al (2010) predicted the probable cause of cytomixis to be persistence of plasmodesmata during meiosis. Cell wall dissolution between the adjacent cells may also lead to cytoplasmic connections (Falistocco et al 1995).…”