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NotificationsNotify me of updates to VARIABLE SIZED POLLEN GRAINS DUE TO IMPAIRED MALE MEIOSIS IN THE COLD DESERT PLANTS OF NORTH WEST HIMALAYAS (INDIA) pp. 101-126
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VARIABLE SIZED POLLEN GRAINS DUE TO IMPAIRED MALE MEIOSIS IN THE COLD DESERT PLANTS OF NORTH WEST HIMALAYAS (INDIA) pp. 101-126 $100.00
Authors:  (Vijay Kumar Singhal, Puneet Kumar, Department of Botany, Punjabi University, Patiala, Punjab, India)
Abstract:
The cold deserts in Western Himalayas spread over approx. 74,809 Km2, cover Leh and Kargil districts of Ladakh in Jammu & Kashmir, Uttarkashi in Uttarakhand and Lahaul- Spiti along with some parts of Chamba and Kinnaur districts of Himachal Pradesh. These cold deserts consist of rugged mountains, snow clad peaks, bare rocks, steep sandy slopes with rock gravels, low capacity of soil to retain moisture, and have oppressive and inhospitable conditions which include freezing temperature, dry arid weather, high velocity winds and low precipitation. As a consequence of such harsh climatic conditions prevailing in these regions, plants tend to become prostrate, thick, bushy, hardy, mat forming and spiny with long roots and small succulent or woolly leaves. Majority of these plants are perennials and survive through underground parts. Further, the plants of the area are exposed to high incidence of UV rays and are under considerable pressure of human intervention and natural disasters which include agriculture, heavy grazing, snow avalanches, windstorms, landslides and increasing entry of tourists and transport vehicles. As a consequence of such stresses, the plants of the area are expected to show considerable amount of irregularities during male meiosis and in pollen grains. Keeping above assumptions in mind the work on cytomorphological diversity in the plants of Lahaul-Spiti, a part of the Western Himalayan cold deserts, was undertaken. During the course of study spanning 5 years (2005-2009) we have come across several species which depict various irregularities during male meiosis resulting into the formation of variable sized apparently fertile/ stained pollen grains and considerable amount of pollen sterility. These heterogeneous sized pollen grains and pollen malformation are reported mainly in species depicting the phenomenon of cytomixis involving chromatin transfer among proximate pollen mother cells (PMCs) viz., (Anemone rivularis, 2n=16; Aquilegia fragrans, 2n=16; Astragalus bicuspis, 2n=16; A. frigidus, 2n=16; A. himalayanus, 2n=16; A. rhizanthus, 2n=16; Caltha palustris, 2n=32; Clematis grata, 2n=16; C. orientalis var. acutifolia, 2n=32; Geranium pratense, 2n=56; Hedysarum astragaloides, 2n=14; Meconopsis aculeata, 2n=56; Medicago falcata, 2n=16; M. sativa, 2n=32; Melilotus officinalis; 2n=16, Parnassia laxmanii, 2n=18; Pleurospermum candollii, 2n=22; P. govanianum, 2n=18; Potentilla atrisanguinea var. atrisanguinea, 2n=84; P. atrisanguinea var. argyrophylla, 2n=84; P. cuneifolia, 2n=28; P. fruticosa var. rigida, 2n=14; Ranunculus hirtellus, 2n=32; R. laetus, 2n=28; Rosularia alpestris, 2n=28; Silene vulgaris, 2n=24; Thalictrum foetidum, 2n=42; Trifolium pratense, 2n=14; T. repens, 2n=16 and Trigonella emodii, 2n=16). The resultant PMCs after partial or complete chromatin transfer in these species depict hyper-, hypoploid and anucleated nature which give rise to apparently fertile diploid (2n), haploid (n), and aneuploid, and sterile or micro pollen grains. Such variable sized fertile and sterile pollen grains are also resulted in species depicting irregular synapsis (Dianthus angulatus, 2n=30; Ranunculus laetus, 2n=28; Rosularia alpestris, 2n=28), spindle irregularities (Potentilla atrisanguinea var. argyrophylla, 2n=84; Ranunculus hirtellus, 2n=32; R. laetus, 2n=28; Rosularia alpestris, 2n=28), triploids (Chrysanthemum pyrethroides, 2n=27; Heracleum brunonis, 2n=33), pentaploids (Agrimonia eupatoria, 2n=70) and polyploids with irregular meiotic course (Chrysanthemum pyrethroides, 4x; Clematis orientalis var. acutifolia, 4x; Potentilla atrisanguinea var. atrisanguinea 12x; P. atrisanguinea var. argyrophylla, 12x; Ranunculus hirtellus, 4x; R. laetus, 4x). Double sized pollen grains referred as ‗2n pollen grains resulted as a result of either direct fusion of two pollen grains (Caltha palustris, Potentilla atrisanguinea var. argyrophylla) or are the end products of fused PMCs (syncytes) as is the case in Meconopsis aculeata and Clematis orientalis var. acutifolia are also recorded. Though cytological status of such variable sized fertile pollen grains could not be ascertained presently, they can play an important role in the origin of intraspecific polyploids, aneuploids and taxa with B-chromosomes. 


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VARIABLE SIZED POLLEN GRAINS DUE TO IMPAIRED MALE MEIOSIS IN THE COLD DESERT PLANTS OF NORTH WEST HIMALAYAS (INDIA) pp. 101-126