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      Induction and evaluation of colchitetraploids of two species of Tinospora Miers, 1851

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          Abstract

          Autotetraploidy, both natural and/or induced, has potential for genetic improvement of various crop species including that of medicinal importance. Tinospora cordifolia (Willdenow, 1806) Miers, 1851 ex Hooker et Thomson, 1855 and T. sinensis (Loureiro, 1790) Merrill, 1934 are two diploid species, which are dioecious, deciduous and climbing shrubs with high medicinal importance. Among the three methods used for induction of polyploidy by colchicine treatment, it was cotton swab method which successfully induced the polyploidy in both species. The morphological and cytogenetical features of the synthetic tetraploids were compared with their diploid counterparts. The tetraploids were morphologically distinct from diploid plants. They exhibited larger organs, such as stem, leaves, inflorescence, fruits, flowers and seeds. The tetraploids were characterized by the presence of low quadrivalent frequency and high bivalent average. Unequal distribution of chromosomes at anaphase I was found in 60% cells. The present study provides important information on the superiority of autotetraploids as compared to diploid counterparts in both species.

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          Most cited references 35

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          Stomatal size in fossil plants: evidence for polyploidy in majority of angiosperms.

           J Masterson (1994)
          Three published estimates of the frequency of polyploidy in angiosperms (30 to 35 percent, 47 percent, and 70 to 80 percent) were tested by estimating the genome size of extinct woody angiosperms with the use of fossil guard cell size as a proxy for cellular DNA content. The inferred chromosome numbers of these extinct species suggest that seven to nine is the primitive haploid chromosome number of angiosperms and that most angiosperms (approximately 70 percent) have polyploidy in their history.
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            The polyploidy revolution then…and now: Stebbins revisited.

            Polyploidy has long been considered a major force in plant evolution. G. Ledyard Stebbins, Jr., an architect of the Modern Synthesis, elegantly addressed a broad range of topics, from genes to chromosomes to deep phylogeny, but some of his most lasting insights came in the study of polyploidy. Here, we review the immense impact of his work on polyploidy over more than 60 years, from his entrance into this fledgling field in the 1920s until the end of his career. Stebbins and his contemporaries developed a model of polyploid evolution that persisted for nearly half a century. As new perspectives emerged in the 1980s and new genetic tools for addressing key aspects of polyploidy have become available, a new paradigm of polyploidy has replaced much of the Stebbinsian framework. We review that paradigm shift and emphasize those areas in which the ideas of Stebbins continue to propel the field forward, as well as those areas in which the field was held back; we also note new directions that plant geneticists and evolutionists are now exploring in polyploidy research. Perhaps the most important conclusion from recent and ongoing studies of polyploidy is that, following Levin and others, polyploidy may propel a population into a new adaptive sphere given the myriad changes that accompany genome doubling. © 2014 Botanical Society of America, Inc.
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              The polyploidy and its key role in plant breeding.

              This article provides an up-to-date review concerning from basic issues of polyploidy to aspects regarding the relevance and role of both natural and artificial polyploids in plant breeding programs. Polyploidy is a major force in the evolution of both wild and cultivated plants. Polyploid organisms often exhibit increased vigor and, in some cases, outperform their diploid relatives in several aspects. This remarkable superiority of polyploids has been the target of many plant breeders in the last century, who have induced polyploidy and/or used natural polyploids in many ways to obtain increasingly improved plant cultivars. Some of the most important consequences of polyploidy for plant breeding are the increment in plant organs ("gigas" effect), buffering of deleterious mutations, increased heterozygosity, and heterosis (hybrid vigor). Regarding such features as tools, cultivars have been generated with higher yield levels, improving the product quality and increasing the tolerance to both biotic and abiotic stresses. In some cases, when the crossing between two species is not possible because of differences in ploidy level, polyploids can be used as a bridge for gene transferring between them. In addition, polyploidy often results in reduced fertility due to meiotic errors, allowing the production of seedless varieties. On the other hand, the genome doubling in a newly formed sterile hybrid allows the restoration of its fertility. Based on these aspects, the present review initially concerns the origin, frequency and classification of the polyploids, progressing to show the revolution promoted by the discovery of natural polyploids and polyploidization induction in the breeding program status of distinct crops.
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                Author and article information

                Contributors
                Journal
                Comp Cytogenet
                Comp Cytogenet
                8
                urn:lsid:arphahub.com:pub:A71ED5FC-60ED-5DA3-AC8E-F6D2BB5B3573
                urn:lsid:zoobank.org:pub:C8FA3ADA-5585-4F26-9215-A520EE683979
                Comparative Cytogenetics
                Pensoft Publishers
                1993-0771
                1993-078X
                2020
                20 May 2020
                : 14
                : 2
                : 211-229
                Affiliations
                [1 ] Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, 201313, India Amity University Noida India
                [2 ] Department of Botany, Hansraj College, University of Delhi, Delhi, 110007, India University of Delhi Delhi India
                [3 ] Department of Biotechnology & Bioinformatics, North Eastern Hill University, Shillong, Meghalaya, 793022, India North Eastern Hill University Shillong India
                [4 ] ICAR- Indian Grassland and Fodder Research Institute, Jhansi, Uttar Pradesh, 284003, India ICAR- Indian Grassland and Fodder Research Institute Jhansi India
                Author notes
                Corresponding author: Soom Nath Raina ( soomr@ 123456yahoo.com )

                Academic editor: E. Mikhailova

                Article
                33394
                10.3897/CompCytogen.v14i2.33394
                7253504
                Rakesh Kr Thakur, Vijay Rani Rajpal, Satyawada Rama Rao, Apekshita Singh, Lata Joshi, Pankaj Kaushal, Soom Nath Raina

                This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                Funding
                Natioanl Medicinal Plants Board, Ministry of Ayush, Government of India
                Categories
                Research Article
                Ranunculales
                Cellular & Organismal genetics
                Asia

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