Department of Botany

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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.
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.
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

Department of Botany

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