Department of Botany
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Item MORPHOLOGY, ANATOMY AND MYCORRHIZAE IN SUBTERRANEAN PARTS OF ZEUXINE GRACILIS (ORCHIDACEAE)(University of Murcia, Spain-Anales de Biologia, 2011-12-14) Muthukumar T; Uma E; Karthikeyan A; Sathiyadash K; Jaison S; Priyadharsini P; Ishworani C; Muniappan VZeuxine gracilis (Berda) Bl., is an endemic, terrestrial green orchid whose morphology, anatomy and mycorrhizal status is unknown. So we investigated: (a) root and rhizome anatomy; (b) root hair characteristics and mycorrhizal colonization patterns in Z. gracilis plants collected from Western Ghats region of southern India. The prominent anatomical characters in the roots were: absence of velamen, spiranthosomes, and the presence of single layered exodermis and nine arched protoxylem. The rhizome had an uniseriate epidermis, abundant spiranthosomes in the inner cortical cells, a distinct endodermis with casparian strips and biseriate vascular bundles. The presence of fungi both in the roots and rhizomes was revealed. The entry of fungi was chiefly through root hairs and through epidermis in the rhizome. Fungi formed pelotons and monilioid cells in the root cortex. Additionally, arbuscular mycorrhizal (AM) fungi characterized by the presence of aseptate hyphae, vesicles and spores were present occasionally in roots. The lack of arbuscules in Z. gracilis indicated the AM to be non functional.Item ROOT MORPHOLOGY AND MYCOTROPHY OF DISPERIS NEILGHERRENSIS (ORCHIDACEAE) FROM WESTERN GHATS, SOUTHERN INDIA(Anales de Biología, 2013-11-13) Muthukumar T; Uma E; Pandey R RWe examined the root morphology and mycotrophy of Disperis neilgherrensis Wight., growing in the Western Ghats of south India for the first time. The root system was sparse consisting of white to off white, 0.28 ± 0.11 mm thick roots arising from short brown rhizome. The roots were covered by root hairs (19.2 ± 1.5 per mm of root) 161.80 ± 12.68 µm long and 4.55 ± 1.17 µm thick. Root cortical cells contained fungal structures typical for orchid mycorrhizal (OM) and arbuscular mycorrhizal (AM) types. In contrast, rhizomes contained only OM fungal structures. The OM colonization was characterized by both lightly and darkly staining pelotons with regularly septate hyphae of varied diameters. Intracellular aseptate hyphal coils, arbusculate coils and intracellular vesicles characterized AM colonization. The percentage of length with OM colonization was 56.51% for roots and 73.64% for rhizomes, whereas the root length with AM fungal colonization was 30.23%. The AM type in D. neilgherrensis corresponds to the Paris-type.Item MORPHOLOGY, ANATOMY AND MYCORRHIZAE IN SUBTERRANEAN PARTS OF ZEUXINE GRACILIS (ORCHIDACEAE)(Anales de Biología, 2011-12-14) Muthukumar T; Uma E; Karthikeyan A; Sathiyadash K; Sarah Jaison; Priyadharsini P; Ishworani C; Muniappan VZeuxine gracilis (Berda) Bl., is an endemic, terrestrial green orchid whose morphology, anatomy and mycorrhizal status is unknown. So we investigated: (a) root and rhizome anatomy; (b) root hair characteristics and mycorrhizal colonization patterns in Z. gracilis plants collected from Western Ghats region of southern India. The prominent anatomical characters in the roots were: absence of velamen, spiranthosomes, and the presence of single layered exodermis and nine arched protoxylem. The rhizome had an uniseriate epidermis, abundant spiranthosomes in the inner cortical cells, a distinct endodermis with casparian strips and biseriate vascular bundles. The presence of fungi both in the roots and rhizomes was revealed. The entry of fungi was chiefly through root hairs and through epidermis in the rhizome. Fungi formed pelotons and monilioid cells in the root cortex. Additionally, arbuscular mycorrhizal (AM) fungi characterized by the presence of aseptate hyphae, vesicles and spores were present occasionally in roots. The lack of arbuscules in Z. gracilis indicated the AM to be non functional