Department of Botany

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Author: search.filters.author.Uma ESubject: search.filters.subject.Arbuscular mycorrhizal fungi

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    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 V
    Zeuxine 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.
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    ROLE OF ORGANIC AMENDMENTS ON ARBUSCULAR MYCORRHIZAL FORMATION AND FUNCTION
    (Nova Science Publishers, 2011) Jaison S; Uma E; Muthukumar T
    The last two decades have seen a renewed interest in organic farming and amelioration of soils affected by conventional agriculture. Different types of organic substances like farmyard manures, green manures, composts, sludges and effluents are added to the soil to enhance fertility. These organic amendments influence soil microbial populations and function. Arbuscular mycorrhizal (AM) fungi are an integral component of most agricultural and natural systems, and provide a range of benefit to the host plant. The prime benefit of AM fungi to plants include improved nutrition especially phosphorus (P) and nitrogen (N) in nutrient stressed soils. Other non-nutritional benefits include improved water relations, enhanced resistance to soil-borne pathogens, improved drought resistance, heavy metal tolerance and soil structure. As most crop and horticultural plants are mycorrhizal any factors that influence AM fungi affects plant growth and productivity. Organic amendments improve plant mycorrhization, AM fungal spore numbers and their diversity. However, certain organic sources rich in certain chemicals like phenols inhibit mycorrhization. The effect of organic amendments on AM fungi depends on the composition of the organic sources.
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    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 V
    Zeuxine 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