Trisomics are aneuploids, carrying an extra chromosome to the normal somatic complement. The nature of this additional chromosome determines its types; normal in primary, isochromosome in secondary, and translocated in tertiary or interchange types. The extra chromosome causes meiotic irregularities manifested by its abnormal associations at metaphase I and unequal separation of chromosomes, laggard and bridge formation at anaphase I. This leads to the formation of unbalanced gametes (n+. 1) in trisomic individuals. Poor viability and vigor of n+. 1 gametes severely reduce the transmission rate of trisomics through the disturbances in prezygotic, zygotic, and postzygotic stages. Since the trisomics carry an extra chromosome, the modified segregation ratios have immense significance in comprehensive genome mapping using both classical and molecular markers. © 2013 Elsevier Inc. All rights reserved.

D TALUKDAR

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Brenner's Encyclopedia of Genetics: Second Edition

Prominent primary aneuploid stocks namely seven primary trisomics, seven primary tetrasomics, and six double trisomic types were earlier developed in grass pea (Lathyrus sativus L.), a hardy legume. Despite distinct morphological features, identity and nature of their extra chromosome(s) were elusive, hampering assignment of desirable breeding traits into specific linkage groups. The present study aims to analyze the banding pattern and to reveal the identity of extra chromosome(s) involved in these 20 aneuploid types in grass pea. Conventional orcein banding was first done using the root-tip squash technique in all aneuploids along with disomic (2n = 2x = 14) parent, and karyomorphological features were noted. Chromosomes were classified following the total length of individual chromosomes and arranged in order of decreasing sizes, keeping their centromeres in a straight line. DNA-base specific chromomycin A3 (CMA) and 4,6'diamidino-2-phenylindole (DAPI) banding pattern were finally employed to convincingly distinguish the chromosomes from each other. Molecular banding and idiograms revealed unique CMA and DAPI banding pattern in each of the seven chromosome pairs and identified extra chromosome(s) involved in aneuploidy. Fluorescence banding also showed differential CMA-specific GC-rich repeat region and DAPI-specific AT-rich repeat regions in chromosomes with the longest chromosome bearing GC-rich nucleolar organizing region. No polymorphism within homologous pairs was found. The result confirmed the primary nature of present aneuploids and identified the additional chromosome(s) in aneuploids. Based on the extra chromosome(s) involved, new designation of grass pea aneuploids has now been proposed. The results have immense significance in location of desired traits or mutations on specific linkage groups of grass pea.

Fulltext

Caryologia

RETRACTED: Karyotype analysis and identification of extra chromosomes in primary aneuploid stocks of grass pea (Lathyrus sativus L.) by fluorescence chromosome banding(Retracted article. See vol. 70, pg. 92, 2017)

Response of four improved grass pea (Lathyrus sativus L.) genotypes to arsenic was tested in pot experiment using 30 mg As l-1 up to 60 days of growth after commencement of treatment (DAC). Arsenic exposure significantly reduced growth and seed yield potential of vars B1 and BioL-212, but no such effect was observed in bold-seeded mutant and pod indehiscent mutant lines. Results revealed normal leaf photosynthesis and antioxidant metabolism at 20 DAC in both varieties. However, high superoxide dismutase activity coupled with low ascorbate redox and declining ascorbate peroxidase level led to abnormal rise in H2O2 content at reproductive stages (40 and 60 DAC), consequently, resulting in significantly enhanced arsenic-induced oxidative damage and physiological impediment in both varieties. By contrast, H2O2 level in both the mutants was remarkably modulated at reproductive stage (40 DAC) in a highly controlled manner by balanced action of antioxidant defense. This favored normal photosynthesis and ensured good grain yield even under prolonged arsenic exposure by effectively preventing oxidative damage to membrane in both the mutants. Native PAGE analysis revealed that enzyme isoforms were involved in the regulation of foliar H2O2 metabolism, the level of which was found extremely critical in determining arsenic tolerance of grass pea genotypes. © 2013 NAAS (National Academy of Agricultural Sciences).

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