Persistent occurrence of meiotic abnormalities in a new hexaploid cytotype of <Emphasis Type="Italic">Thalictrum foetidum</Emphasis> from Indian cold deserts |
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Authors: | Vijay Kumar Singhal Pawan Kumar Rana Puneet Kumar Dalvir Kaur |
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Institution: | (1) Department of Plant Pathology, The Ohio State University, Wooster, OH 44691, USA; |
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Abstract: | Thalictrum foetidum L. (Ranunculaceae), a morphologically variable and widely distributed species of temperate and alpine Himalayas is worked
out cytologically for the first time from India. Earlier studies from outside India were restricted to chromosome counts and
karyotypic analysis. We studied the male meiosis, microsporogenesis and pollen viability in the wild accessions from the cold
deserts of Lahaul-Spiti, Kinnaur and Pangi Valley of Himachal Pradesh. Present cytomorphological surveys in the species record
the existence of two distinct morphotypes involving plant size; colour and size of leaf/leaflet; dentation of leaflet lobes;
and degree of leaf pubescence. All the accessions in the two morphovariants share the same meiotic chromosome number (n = 21) and adds a new intraspecific hexaploid cytotype. The accessions show the phenomenon of cytomixis involving transfer
of chromatin material among proximate pollen mother cells (PMCs) and associated meiotic abnormalities like, out of plate bivalents,
interchromosomal connections, and laggards, bridges and micronuclei at anaphases/telophases. Microsporogenesis results into
abnormal sporads (tetrads with micronuclei, dyads, triads and polyads). The products of such sporads resulted into some pollen
sterility and pollen grains of heterogeneous sizes. The persistent occurrence of phenomenon of cytomixis and associated meiotic
abnormalities and consequently pollen sterility and pollen grains of heterogeneous sizes in the hexaploid cytotype of T. foetidum seems to be under some genetic factors associated with the genome. |
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