Five translocation heterozygotes were induced by using gamma rays in Pisum sativum. The induced translocations showed a ring or chain of 4 chromosomes and 5 bivalents in most of the PMCs at diakinesis/metaphase I. Translocation heterozygotes predominantly showed an adjacent type of orientation as compared to alternate orientations of the centromeres which is reflected in the pollen stainability and pollen fertility of the plants. The translocation heterozygotes established could be used for gene mapping and the production of trisomics. They would have altered karyo-types useful for other experimental studies on Pisum sativum. Pisum sativum L. (2n=14) commonly known as pea, of the family Fabaceae is an important le-gume grown and consumed extensively worldwide. As a rich source of protein, carbohydrates, and vitamins, pea is important in human nutrition. Consumed mostly as green peas, total production worldwide is around 8.3 million tons (FAO 2008). Pea is the fourth leading legume in terms of world consumption and the second most important legume after the common bean (Phaseouls vul-garis L.) in India with a total annual production of 3,029.40 tons (NHB 2010). Identification of agriculture via mass use of chemical fertilizers has dramatically reduced natural soil fertility potential, while legumes have a unique ability to assimilate atmospheric nitrogen in symbiosis with soil bacteria. In addition, pea is one of the best models to study triple symbiosis (legumes-arbuscular mico-rhizal fungi-nodule bacteria). Mutations are heritable changes in all living organisms, whether occurring spontaneously or induced artificially. Spontaneous mutations occur in nature in all organisms without mans interference. In induced mutations, however, man interferes with plants and animals by artificially inducing in them mutations by various mutagens like chemical mutagens and irradiations. Studies on the effects of ionizing radiations and their utility in inducing chromosome mutations have been a topic of immense interest for cytologists. Mutation techniques have proven useful in obtaining novel traits and creating genetic variability. Gamma irradiation as a mutagen can induce useful as well as harmful mutations in plants. In the present study, for the genetic improvement of pea, induced mutations through gamma rays were attempted and 5 translocation heterozygotes have been isolated as a result. Translocation heterozy-gotes are characterized by the occurrence of new morphological chromosomal units out of segments of non-homologous chromosomes. Recently, Sybenga et al. (2012) have found that trisomy greatly enhances interstitial crossing-over in a translocation heterozygote of Secale. The aim of the present study was to induce translocation and if possible produce a genetic map of the P. sativum, as has been done for Vicia faba (Rieger and Michaelis 1962, Schubert et al. 1982, 1991). Karyotype reconstruction either natural or induced is of great importance to plant breeders and geneticists (Schubert et al. 1991). Here, we present a...

Summary Seeds of Lens culinaris Medik (Lentil) were irradiated with various doses of gamma rays, (viz. 5 kR, 10 kR, 15 kR, 20 kR, 25 kR and 30 kR) and some seeds were also treated with different concentrations (0.1, 0.2, 0.3, and 0.4%) of Ethyl Methane Sulphonate (EMS) for 6 and 12 h in separate experiments. Two plants, one translocation heterozygote and one inversion heterozygote, were isolated from the population raised from 10 kR gamma ray-irradiated seeds and 0.2% EMStreated seeds, respectively. The mutant plants displayed various types of chromosomal configurations at diakinesis/metaphase I, and anaphase/telophase I/II in meiosis. The translocation heterozygote exhibited the formation of ring/chain of four and six chromosomes in a majority of the PMCs at diakinesis/metaphase-I, and the inversion heterozygote was characterized by the presence of bridge and fragments at anaphase/telophase I/II because of various numbers and positions of crossovers in the inversion loop. Pollen fertility declined to 38% in the translocation heterozygote and 27.33% in the inversion heterozygote as compared to 96% in the control.

SummaryPolyploidy was induced by colchicine in Allium cepa L. Five plants of Allium cepa (AC1-AC5) were isolated from the 0.2% colchicine treated inflorescences. The meiotic stages were analyzed in treated buds. Various cytological features like chromosomal associations (quadrivalents, bivalents and univalents), chiasmata frequency and terminalization coefficient were recorded at diakinesis/metaphase-I. Anaphase/telophase-I/II were studied in all the cholchitetraploids. In all these plants, the anaphase/telophase-I were abnormal showing unequal distribution, laggards, micronuclei and multipolar at telophase-II. Pollen mitosis was studied in these plants. The chromosomes (n=16) were found at metaphase. Pollen fertility was low (40.9 to 56.9%) in all colchitetraploids.Key words Induced colchitetraploid, Allium cepa L., Pollen fertility, Colchicine, Chromosome.The importance of polyploid plants in agriculture is well known. Colchicine has been largely used to alter ploidy level frequencies in cell populations to obtain tetraploid plants, starting with diploid material. In fact, polyploid plants usually have larger and thicker leaves, stems or roots, and also flowers, fruits and seeds, and then, a greater yield (Gao et al. 1996).The genus Allium consists of 700 species in the world (Friesen et al. 2005). Allium cepa L. is one of the most important plant species which was cultivated thousands of years ago as an edible plant (Jamila et al. 2009). Its chromosome number is low (2n=16), and it has a relatively large size and is susceptible to cytological manipulations (Mercykutty and Stephen 1980). The present investigation was planned to induce polyploidy in Allium cepa by colchicine treatment and identify the ploidy level by counting the chromosome number. Materials and methods Colchicine treatmentYoung inflorescences were treated with 0.2% colchicine solution for 6, 12, 18, or 24 h also by using the cotton swab method . After treatment inflorescences were thoroughly washed with water. Study of meiosisFor meiotic studies, young flower buds of appropriate size were collected between 10 to 11 AM and fixed in freshly prepared Carnoy s fluid (absolute alcohol and acetic acid in 3 : 1 ratio). Anthers were separated, teased in a drop of 2% iron acetocarmine on a clean slide and squashed under a cover glass. Pollen mother cells (PMCs) were analyzed for suitable stages of meiosis. Temporary slides were analyzed for different stages of meiosis like diakinesis, metaphase-I, anaphase-I, telophase-I and -II. Chromosomal associations, chiasmata frequency, distribution of chromosomes and other features were recorded. Chiasma frequency was calculated according to Ward (1979).