Cytological Analysis in the Microsporogenesis of Ramie, Boehmeria nivea Gaud. (Urticaceae) and the Effect of Colchicine on the Chiasma Frequency.

Abstract

Boehmeria nivea Gaud., the popular ramie (or China grass) is a perennial, wind-pollinated, monoecious plant with small diclinous flowers (Rabechault 1951). It is well known for its long and resistent extra-xylary (secondary phloem) textile fibers (Fahn 1975). Ramie has also been exploited as a forage during the winter when the plants grow slowly and are not so good for fiber extraction (Benatti Jr. 1988). The species is native from the temperate asiatic regions and comprises many varieties with asexual propagation by rhizomes. Chromosome numbers was first established as 2n=28 by Krause (1930, cited by Krause 1931, for B. nivea and B. biloba and this number was later confirmed by Medwedewa (1934), even though they did not mention in which variety they worked.Studies on polyploidy induction in ramie with colchicine were done by some researchers as Chi and Lai (1964) and Dong et al. (1988) with the purpose of plant fiber improvement. However, there are few cytological informations from this kind of study related to microsporogenesis, to chromosome behavior or degrees of pollen fertility.So, the present work deals with microsporogenesis analysis in some plants of one ramie variety which were treated with colchicine solution, but without chromosome duplication. Materials and methods Materials and colchicine treatmentSeeds of Boehmeria nivea var. 'Miyasaky' were soaked in 0.1 % colchicine solution for 24 hr, then washed in distilled water, placed in Petri dishes with moist filter paper until germination. Germinated seeds were transferred to Petri dishes with filter paper soaked in 0.1 % colchicine solution for 18 hr. After this, seeds and radicules were carefully washed in distilled water and placed in other 214 Neiva Izabel Pierozzi and Romeu Benatti Jr.Cytologia 63

First Report of Cytomixis and Meiotic Abnormalities in <i>Nepeta govaniana</i> from Solang Valley, Kullu District, Himachal Pradesh

“…However, the two accessions scored from high altitudinal regions around Dhundhi and Solang Village showed the phenomenon of cytomixis and associated meiotic abnormalities resulting in abnormal sporads and heterogeneously sized fertile pollen grains. The frequency of cytomixis involving chromatin transfer was much higher during the early stages of meiosis I than meiosis II, which has also been reported in a number of cases (De and Sharma 1983, Consolaro and Pagliarini 1995, de Souza and Pagliarini 1997, Pierozzi and Benatti 1998.…”

Cytomixis Induced Meiotic Irregularities and Pollen Malformation in Clematis graveolens Lindley from the Cold Deserts of Kinnaur District of Himachal Pradesh (India)

“…All the individuals of 3 morphovariants detected presently uniformly existed at diploid level. Throughout the meiotic course, the phenomenon of cytomixis has been observed but its occurrence is more frequent during meiosis-I as has also been noticed earlier by other researchers (De and Sharma 1983, Consolaro and Pagliarni 1995, Pierozzi and Benatti 1998. The nature of chromatin transfer in the PMCs is either partial or complete.…”

Cytomixis during Microsporogenesis in Some Populations of <i>Croton bonplandianum</i> of North India

“…Actual chromosome/chromatid transfer was greater in PMCs at the first meiotic division and here too at metaphase-1 than the PMCs at the second meiotic division. More frequent occurrence of cytomixis during meiosis-I as compared to meiosis-II has been recorded by earlier researchers also (Cheng et al 1980, Mantu and Sharma 1983, Consolaro and Pagliarini 1995, Pierozzi and Benatti 1998, Lattoo et al 2006, Singhal and Kumar 2008, Kumar et al 2010. The amount of chromatin transfer varied from a small part to the entire complement thus making the donor cell empty (Fig.…”