Chromosome number and modal karyotype in a polysomatic endangered orchid, Bulbophyllum auricomum Lindl., the Royal Flower of Myanmar |
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Authors: | Myo Ma Ma Than Amita Pal Sumita Jha |
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Institution: | 1. Centre of Advanced Study, Department of Botany, University of Calcutta, 35, Ballygunge Circular Road, Kolkata, 700 019, India 3. Mingalardon Orchid Garden, Yangon, Myanmar 2. Division of Plant Biology, Bose Institute, P1/12 CIT Scheme VIIM, Kolkata, 700 054, India
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Abstract: | A detailed account is presented of attendant polysomatic variation in planta and elucidation of the modal karyotype in the difficult-to-study endangered orchid Bulbophyllum auricomum, known as the Royal Flower of Myanmar. The somatic chromosome number of B. auricomum (2n?=?38) is reported for the first time. Polysomaty was prevalent in all seed-derived plants studied except two (SC34 and SC42). It was noted that in addition to normal diploid cells occurring in different frequencies (60% in SC21 to 89% in SC22, SC35), root tip cells also showed chromosome numbers <38 (in 0?C37% metaphases) and >38 (in 0?C33% metaphases). The chromosomes of B. auricomum are very small (0.7?C2.7???m) in size. The karyotype of diploid B. auricomum showed 34 chromosomes with primary constriction (14?M?+?16?m?+?4sm) and 4 chromosomes with secondary constrictions (sm:sm). Of the 50 plants analyzed, 2 (SC34 and SC42) were polyploid, showing 70 and 62 chromosomes in the root tip cells. The polyploidization in seed-derived plants clearly indicates the heterogeneous nature of orchid seed stock. Early detection of polyploidization in in vitro?Cpropagated B. auricomum is valuable for conservation of this native endangered orchid species. On the other hand, the clonally propagated plants retained the chromosomal status of parent plants. This protocol could be exploited to protect this native endangered orchid species from natural extinction. |
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