Browsing by Author "Muthukumar T"

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ARBUSCULAR MYCORRHIZAL (AM) AND DARK SEPTATE ENDOPHYTE (DSE) FUNGAL ASSOCIATION IN LYCOPHYTES AND FERNS OF THE KOLLI HILLS, EASTERN GHATS, SOUTHERN INDIA
(American Fern Journal, 2014) Muthuraja R; Muthukumar T; Sathiyadash K; Uma E; Priyadharsini P
We examined the extent and type of arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in three lycophyte and 44 fern species collected from three different sites in the Kolli Hills, Eastern Ghats, southern India. Of the 47 plant taxa (belonging to 21 families and 33 genera) examined, 46 had AM fungal and 33 had DSE fungal associations. But, fungal structures were absent in the aquatic fern Azolla pinnata (Azollaceae). This is the first report of AM and DSE fungal status for 16 and 28 species, respectively. Among terrestrial lycophytes and ferns, 26 species had dual association of both AM and DSE fungi, whereas 11 species had only AM fungal association. Vittaria elongata from epiphytic habitats had dual association of AM and DSE fungi. Likewise, Cheilanthes tenuifolia (saxicolous or terrestrial), Cheilanthes opposita, Lepisorus nudus, Pyrrosia lanceolata (terrestrial or epiphytic), and Asplenium lanceolatum (saxicolous or epiphytic) examined from different sites or habitats also had dual association of AM and DSE fungi. Seventy two percent of the mycorrhizal lycophytes and ferns had intermediate-type AM and 15 percent had both Paris- and intermediate-types at different sites. Significant variations in AM fungal structures were evident in 16 ferns occurring in two or more sites. Nine AM fungal spore morphotypes belonging to Acaulospora, Funneliformis, Glomus, Gigaspora, and Sclerocystis were found to be associated with lycophytes and ferns
ARBUSCULAR MYCORRHIZAL AND DARK SEPTATE ENDOPHYTE FUNGAL ASSOCIATIONS IN FERNS AND LYCOPHYTES OF PALNI HILLS, WESTERN GHATS, SOUTHERN INDIA
(Brazilian Journal of Botany, 2014) Muthukumar T; Sathiyaraj G; Priyadharsini P; Uma E; Sathiyadash K
WWe assessed the arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal associations in 57 ferns and 3 lycophytes (belonging to 15 families in 39 genera) of different life forms (epiphytic, saxicolous and terricolous) occurring in Palni Hills of Western Ghats. Fungal symbiosis was absent in all the three lycophytes examined. Fifty-five of the 57 ferns (91.66 %) examined had AM and 37 (64.91 %) had DSE fungal association. This is the first report on AM and DSE fungal association for 22 and 30 species, respectively. In addition, AM morphology was evaluated for the first time in 34 species. Sixty-five percentage of the mycorrhizal ferns had intermediate- type AM and 19.30 % had typical Paris-type AM morphology. Both Paris- and intermediate-type AM morphologies were observed in 10.53 % of ferns. The root length colonized by AM and DSE fungal structures significantly varied among species, and a significant negative relation existed between the root length colonized by AM and DSE fungi.
ARBUSCULAR MYCORRHIZAL AND DARK SEPTATE ENDOPHYTE FUNGAL ASSOCIATIONS IN SOUTH INDIAN GRASSES
(Symbiosis, 2010-10-21) Sathiyadash K; Muthukumar T; Uma E
We examined arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungal association in 50 south Indian grasses from four different sites. AM fungal diversity was also compared among the different sites. Forty-four of the 50 grasses examined had AM association and dual association with DSE fungi occurred in 25 grasses. We report for the first time AM and DSE fungal status in 23 and 27 grasses respectively. Arum-type AM morphology was the dominant occurring in 21 grasses with typical Paris-type colonization occurring in 6 grasses. AM morphology is reported for the first time in 35 grasses. Over the different sites, spore density in the soil ranged from 5–22 per 100 g air-dried soil. Spores of 11 AM fungal taxa were isolated from the soil samples of grasses of which nine belonged to Glomus, one to Acaulospora and one to Scutellospora. No significant relationship existed between AM fungal colonization and spore numbers. Species richness was high in site II and Glomus aggregatum, Glomus viscosum and Glomus mosseae were most frequent species at different sites. Overall species diversity indices (Simpson index, Shannon-Weaver index, species equitability index) differed significantly between sites
ARBUSCULAR MYCORRHIZAL FUNGAL ASSOCIATIONS IN ZINGIBERACEAE AND COSTACEAE
(The Postgraduate & Research Department of Botany, St. Thomas College, Kozhencherry, Kerala, India, 2009-10-28) Uma E; Sathiyadash K; Muniappan V; Sarah jaison; Muthukumar T
We provide information on the AM fungi incidence exclusively in Zingiberaceae and Costaceae, which will provide an opportunity to extend our knowledge on the AM association in these plant families
ARBUSCULAR MYCORRHIZAL FUNGAL STRAINS AND SOIL TYPE INFLUENCE GROWTH, NODULATION, AND NUTRIENT UPTAKE OF CASUARINA EQUISETIFOLIA
(Springer, 2013) Muthukumar T; Uma E; Priyadharsini P
The effects of arbuscular mycorrhizal (AM) fungal species and strains on seedling growth and uptake of nutrients were determined for Casuarina equisetifolia under nursery conditions. Seedlings of C. equisetifolia were inoculated individually with four strains each of Acaulospora scrobiculata and Glomus aggregatum in two soil types (alfisol and vertisol). Seedling height, root collar diameter, nodulation, dry weights, nutrient contents, nutrient uptake efficiencies, mycorrhizal inoculation effect (MIE), and seedling quality were determined at harvest. Seedlings inoculated with different AM fungal strains invariably had significantly higher plant growth, and nutrient parameters measured. Nevertheless, the response was higher for seedlings inoculated with strains of G. aggregatum compared to those inoculated with strains of A. scrobiculata. The mycorrhizal response as measured by MIE was significantly affected by soil types. These results suggest the importance of selecting a specific AM fungal strain suited for a soil type in forest nurseries for the production of high-quality seedlings.
ARBUSCULAR MYCORRHIZAL MORPHOLOGY IN SPOROPHYTE OF PSILOTUM NUDUM
(Phytomorphology: An International Journal of Plant Morphology, Scientific Publishers, 2009) Muthukumar T; Sathiyadash K; Uma E; Muniappan V
The mycorrhizal structures of the sporophyte of Psilotum nudum were studied by light microscopy. Further, the nature of the fungal associate was characterized through trap-culture technique. The fungal entry into the rhizome was mainly through the rhizoids with occasional direct entry through the epidermis. The fungal colonization resembling the Paristype of mycorrhiza was restricted to the cortex with the rhizome tip and the stele free of any colonization. The transversing hyphae formed coils in the host cells with intracellular vesicles, but arbuscules were absent. Single hyphae arising from the coils penetrated the neighbouring cells with a hyphal constriction at the host cell wall region. Intact and collapsed hyphal coils were found in different cells and no recolonization of the host cells was observed. Arbuscular mycorrhizal fungal spores belonging to Acaulospora scrobiculata, Glomus aggregatum and Glomus geosporum were isolated from the trap cultures and also from the soil in which P. nudum occurred
ASYMBIOTIC SEED GERMINATION, MYCORRHIZATION AND SEEDLING DEVELOPMENT OF ACAMPAE PRAEMORSA (ROXB.) BLATT. & MC CANN, A COMMON SOUTH INDIAN ORCHID
(Elsevier- Asian Pacific Journal of Reproduction, 2013-06-20) Sathiyadash K; Muthukumar T; Bala Murugan S; Sathishkumar R; Uma E; Jaison S; Priyadharsini P
To develop conservation strategies for orchid species. Methods Seeds of Acampae praemorsa (Roxb.) Blatt. Mc Cann ( A. praemorsa ) were obtained from mature pods collected from Velliangiri hills and germinated on Murashige and Skoog (MS) medium supplemented with various concentration of Benzylaminopurine (BAP). Results Maximum seed germination (85%) was observed on MS media supplemented with 2 mg/L BAP. Seed germination percentage increased with increasing concentrations of BAP (0.5 mg/L to 2 mg/L), but 3 mg/L of BAP inhibited seed germination. Variations observed were significantly ( P ex vitro conditions. Conclusions In present study all the mycorrhizal seedlings survived, because orchid mycorrhizal fungi enhance growth of orchid plantlets and present study gives an effective protocol for seed germination and plantlet regeneration from immature seeds which can be used for establishing A. praemorsa populations in Velliangiri Hills and elsewhere.
CHROMIUM ACCUMULATION IN PLANTS OF THERAPEUTIC VALUE GROWING NATURALLY ON TANNERY POLLUTANT CONTAMINATED AND NON-CONTAMINATED SOILS
(Springer- Biological Trace Element Research, 2016-05-25) Jaison S; Muthukumar T
Herbal preparations used to treat human ailments globally can be contaminated with various heavy metals (HMs) originating from the raw materials or from the manufacturing processes. Therefore, we assessed 22 medicinal plants growing naturally on tannery pollutant contaminated (Site-C) and non-contaminated (Site-NC) sites for their ability to accumulate chromium (Cr). The Cr contents in soil and various plant parts were estimated using an atomic absorption spectrophotometer. Translocation and bioconcentration factors were calculated. The soil at Site-C had 27-fold higher concentration of total Cr than at Site-NC. Chromium accumulation is reported for the first time in 50 % of the medicinal plants examined and varied significantly among the sites. Shoots of Ricinus communis and Amaranthus viridis had maximum concentrations of Cr at Site-C, whereas in Site-NC, none of the plants had Cr accumulation >30 ppm. Ricinus communis, Amaranthus viridis, and Amaranthus spinosus had translocation factor (TF) greater than the one in the Site-C and Lantana camara had TF >1 in Site-NC. The bioconcentration factor (BCF) was >1 only for Ricinus communis at both the sites. The majority of the medicinal plants at Site-NC had Cr content exceeding the permissible limit of 2 ppm suggested for herbal raw material. The results of the study clearly emphasize the need for screening plants of therapeutic value for the presence of HMs even when collected from non-contaminated soils. Moreover, proportional allocation of Cr in different plant parts provided an insight on the safety of these parts when specifically used in herbal preparations.
COMPARATIVE ROOT MORPHOLOGICAL ANATOMY OF ZINGIBERACEAE. SYSTEMATICS AND BIODIVERSITY
(Systematics and Biodiversity, 2014-02-10) Uma E; Muthukumar T
The root anatomy and morphology of 23 species of Zingiberaceae from three tribes and eight genera were examined. Roots were sectioned, with a microtome or freehand, and examined using a variety of staining techniques. The anatomical characters of roots were thoroughly studied and analysed laying emphasis on 21 qualitative and 16 quantitative characters. Statistical tools such as UPGMA Cluster analysis, PCoA and PCA were used to elucidate species boundaries. The prominent anatomical characters in the roots were as follows: all the gingers examined had a piliferous epidermis, followed by an exodermis which contained one or more layers of compact, suberized cells. The cortex had two regions (outer and inner layers) with intercellular air spaces that were radially extended, either linear (Curcuma spp. and Kaempferia galanga), tetrangular (Zingiber officinale), or triangular. The uniseriate endodermis had U-shaped thickening at maturity. Stele included a thin-walled, uniseriate pericycle and polyarch vascular tissues. Phloem strands in Alpinia, Curcuma, Hedychium and Zingiber often extended radially inwards, forming phloem islands. The peripheral ground tissues of stele were mostly fibrous and occasionally parenchymatous. The medulla commonly occupied the centre of the stele. Tuberous roots of Globba, Hedychium and Kaempferia had a wide, starch-filled cortex with stele diameter similar to non-tuberous roots. Oil cells were found in Alpinia spp. and members of the tribe Zingibereae. Starch grains were also found in the parenchymatous cortex and medulla in Hedychium. The perforation plates of the tracheary elements were scalariform to simple. Anatomical characters of the roots in Zingiberaceae could not only help in the identification of the plant species but also in authenticating plant materials used in medicine. A phylogenetic analysis of anatomical characters provided information regarding the closely allied species and could be further confirmed by molecular techniques.
INFLUENCE OF ORGANIC POLLUTANTS ON ARBUSCULAR MYCORRHIZAL FUNGI
(Nova Science Publisher, 2010) Uma E; Jaison S; Muthukumar T
The numerous benefits contributed by arbuscular mycorrhizal (AM) fungi has lead to recognition of their benefits in sustainable agriculture and various natural environmental processes. Application of anthropogenic and other compounds intentionally in the form of pesticides, fungicides, fertilizers or unintentionally like polycyclic aromatic hydrocarbons (PAH) which affect soil fungi have shown varying effects on AM association. Not all organic pollutants are detrimental to AM fungi. Some fungicides such as Fludioxonil have a stimulatory effect on mycorrhizal formation and function. Rapid decrease in the metabolic activity of AM fungi, a decline in arbuscule production, which is the main site of nutrient exchange between the host plant and the fungus, reduction in the total root length colonized and slow colonization rates are the negative effects shown by certain fungicides. Pesticides generally inhibit AM colonization and spore numbers. Slow release mineral fertilizers though benefit AM fungi, their excessive use can result in suppression of the AM fungi. Certain PAH especially anthracene reduce the development of extra radical mycelium, sporulation, root colonization and spore germination. Different AM fungal species show differential sensitivity even within a particular class of organic pollutant. Caution should also be exercised while irrigating soils with effluents as these could affect AM fungi. A reduction in our dependency on conventional agricultural practices especially organic pesticides by using AM fungi as a biological tool which is possible only by maintaining low levels of organic pollutants in the soil. Minimal use of organic pollutants especially pesticides would enable the maintenance of a healthy AM fungal populations essential for sustainable plant production systems.
INVITRO ASYMBIOTIC SEED GERMINATION, MYCORRHIZATION AND SEEDLING DEVELOPMENT OF ACAMPAE PRAEMORSA (ROXB.) BLATT. & MC CANN, A COMMON SOUTH INDIAN ORCHID
(Asian Pacific Journal of Reproduction, 2013-06-20) Sathiyadash K; Muthukumar T; Bala Murugan S; Sathishkumar R; Uma E; Jaison S; Priyadharsini P
Objective: To develope a conservation strategies for orchid species. Methods: Seeds of Acampae praemorsa (Roxb.) Blatt. Mc Cann (A. praemorsa) were obtained from mature pods collected from Velliangiri hills and germinated on Murashige and Skoog (MS) medium supplemented with various concentration of Benzylaminopurine (BAP). Results: Maximum seed germination (85%) was observed on MS media supplemented with 2 mg/L BAP. Seed germination percentage increased with increasing concentrations of BAP (0.5 mg/L to 2 mg/L), but 3 mg/L of BAP inhibited seed germination. Variations observed were significantly (P<0.01) different for concentrations of growth regulators, days and their interactions. The embryos in the seeds swelled prior to germination. Fifty days after inoculation, well developed greenish porotocorm like bodies (PLBs) were formed and by 80th day, 85% (maximum) of the PLBs were observed in MS supplemented with 2 mg/L BAP. Eighty days after seed sowing, the germination rate decreased and the PLBs were transformed into first and second leaf stages in media supplemented with Naphthaleneacetic acid (NAA). Maximum seedling numbers (84%) were observed in MS medium supplemented with 1 mg/L NAA at 110th day. After 110 days, the seedlings were transferred to 0.6 g/L MS medium containing activated charcoal and similar concentration of growth regulators for root induction. After rooting, the seedlings were transferred to ex vitro conditions. Conclusions: In present study all the mycorrhizal seedlings survived, because orchid mycorrhizal fungi enhance growth of orchid plantlets and present study gives an effective protocol for seed germination and plantlet regeneration from immature seeds which can be used for establishing A. praemorsa populations in Velliangiri Hills and elsewhere.
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.
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
MORPHOLOGY, ANATOMY AND MYCOTROPHY OF PSEUDOBULB ANDSUBTERRANEAN ORGANS IN EULOPHIA EPIDENDRAEA AND MALAXIS ACUMINATA (EPIDENDROIDEAE, ORCHIDACEAE)
(Flora, 2015-10-03) Uma E; Rajendran R; Muthukumar T
The pseudobulbs and subterranean organs (roots and rhizomes) of Eulophia epidendraea, and Malaxis acuminata in subfamily Epidendroideae (Orchidaceae) were investigated to determine morphology,anatomy and mycorrhizal occurrence. The examined sections showed the following common anatomi-cal characteristics. The pseudobulbs had a uniseriate epidermis. The assimilatory cells were scattered inthe form of mucilage/water storage cells in the ground tissue. The vascular bundles were collateral andembedded in the ground tissue. Raphides occurred as idioblasts. Rhizomes had an uniseriate epidermis,parenchymatous ground tissue differentiated into outer and inner zones with polygonal intercellularspaces. Vascular bundles scattered, collateral and discontinuous form in both the taxa. Aeration cellswere present in roots and rhizomes of M. acuminata. The transverse section of E. epidendraea roots hadmulti-layered velamen with spiral thickening followed by uniseriate exodermis with passage cells that had webbed tilosomes. The parenchymatous cortex contained raphides and water storage cells. Vascular bundles were 11–15 arched. Roots of M. acuminata had an uniseriate velamen, exodermis, parenchyma-tous cortex, endodermis and pericycle. The vascular bundles were radially arranged, and 11–12 arched.The xylem and phloem were embedded in sclerenchymatous tissue. The entry of the mycorrhizal fungiwas chiefly through root hairs in roots and epidermis in rhizomes of M. acuminata, and in E. epidendraea.Fungi formed pelotons in both the taxa and microsclerotia and monilioid cells in the root cortex of E.epidendraea. Additionally, Glomus- type vesicles were occasionally present in the roots of M. acuminata.Description of characteristics arising from this investigation may provide additional morphological andanatomical means of identification.
MYCORRHIZAL AND DARK SEPTATE FUNGAL ASSOCIATIONS IN GINGERS AND SPIRAL GINGERS
(Botany, 2010-05-05) Uma E; Muthukumar T; Sathiyadash K; Muniappan V
Associations of arbuscular mycorrhizal (AM) and dark septate endophyte (DSE) fungi with 38 ginger species (Zingiberaceae) and two spiral gingers (Costaceae) were investigated. All species were mycorrhizal, and the status of 35 gingers and one spiral ginger has been investigated for the first time. The extent of AM colonization and the root length colonized by AM structures varied significantly among species. AM structures were also observed in non-root portions such as scale leaves. Arbuscular mycorrhizae were of either Aram-type or intermediate- type; AM-type is reported for the first time in 37 species. Spores of 16 morphotypes belonging to 4 genera (Glomus, Acaulospora, Scutellospora, Racocetra) were identified from the rhizosphere soil. DSE colonization was found in 22 gingers and 2 spiral gingers. Twenty-two plant species are reported as hosts of DSE fungi for the first time. The extent of total AM and DSE colonization was not correlated
THE MYCORRHIZAL STATUS OF SOUTH INDIAN EPIPHYTIC ORCHIDS
(The Postgraduate & Research Department of Botany, St. Thomas College, Kozhencherry, Kerala, India, 2009-10-28) Sathiyadash K; Uma E; Muniappan V; Sarah jaison; Muthukumar T
The study is to screen certain orchid species growing naturally in southern India for their mycorrhizal status and to assess the role of root morphology in determining the mycorrhizal status of orchids
OCCURRENCE OF FOLIICOLOUS PARASITIC ALGA CEPHALEUROS VIRESCENS ON CULTIVATED ORNAMENTAL PLANTS IN SOUTHERN INDIA
(Botanica Lithuanica, 2014) Muthukumar T; Uma E; Priyadharsini P
The algal leaf spot, caused by Cephaleuros virescens Kunze, has been reported in a wide range of plant species from the tropical and subtropical areas worldwide. Investigations on the presence of algal infection mostly involved wild plants and plantation crops of economic interest. Nevertheless, limited studies have examined cultivated ornamental plants for the presence of C. virescens. During the summer and monsoon seasons of 2011 we examined ten leaves of five plants belonging to 86 ornamental plant taxa in 38 families growing in home gardens in Coimbatore, Tamil Nadu, India for the algal presence. Nine of the 86 plant taxa were found to host the algae C. virescens. Although majority of the investigated species are considered as typical hosts of C. virescens, its infection was found only in nine plant species. Although the incidence of the algal leaf spot disease was in general low, there was significant variation in the frequency of occurrence of the algal lesions and the lesion size among the investigated plant taxa and seasons. On plants of five species (Alpinia purpurata, Ficus benjamina, Ficus elastica “Variegata”, Michelia champaca, Polyalthia longifolia), C. virescens was found during both seasons, while infections on the remaining four species (Aglaonema commutatum, Dieffenbachia maculata, Eucalyptus globulus, Syngonium podophyllum) were observed only during the monsoon. The susceptibility of different plant species in a genus and varieties of a species varied suggesting the host influence on the development of infections in addition to variation attributed to the local environmental conditions.
ROLE OF ARBUSCULAR MYCORRHIZAL FUNGI IN ALLEVIATION OF ACIDITY STRESS IN PLANT GROWTH
(Springer- NewYork, 2014) Muthukumar T; Priyadharsini P; Uma E; Jaison S; Pandey R R
Soil acidity is a major constraint for crop production worldwide as nearly half of the potential arable lands are acidic. Plant productivity in acid soils is limited by toxic levels of aluminum (Al), manganese (Mn), and iron (Fe) as well as deficiencies of plant available nutrients, especially phosphorus (P). Plants have developed several morphological, biochemical, and physiological adaptations against acidity stress. Among these, symbiosis with arbuscular mycorrhizal (AM) fungi is a strategy plants have evolved to survive and thrive in acid soils. The AM symbiosis increases plant growth in acid soils through enhanced uptake of nutrients. A reduction in Al and Mn phytotoxicities also occurs in response to AM symbiosis through a number of mechanisms such as binding of the toxic ions by the fungal hyphae, vesicles or auxiliary cells, exudation of organic acids, phosphatases, and production of glomalin. However, like plants, AM fungal species and ecotypes also vary to a great extent in their tolerance and ability to impart plant growth benefits in acid soils. It is, therefore, essential to identify suitable AM fungi that could confer tolerance and render maximum benefits to crops in acid soils.
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.
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 R
We 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.