Histopathology of Seed-Borne Infections - Applied Research Center ...

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Location of Fungal Hyphae in Seeds 1375.5.4.1.5 CercosporaCercospora species cause serious diseases of Arachis hypogaea, Glycine max, andBeta vulgaris. Cercospora kekuchii and C. sojina cause purple seed stain and seeddiscoloration of soybean, respectively. Ilyas et al. (1975) found hyphae of C. kekuchiiconfined to the seed coat, but Singh and Sinclair (1985, 1986) observed theiroccurrence in the seed coat, endosperm, and embryo. Singh and Sinclair (1985),using symptomatic seeds with gray to brown discoloration of the seed coat as wellas cotyledons (collected from uninoculated and artificially inoculated plants byC. sojina), found that the pathogen colonized the seed coat tissues (Figure 5.16A),the space between the seed coat and embryo, and, rarely, the hypocotyl-radicle regionof the embryo. Abundant hyphae occurred in the hilar region including tracheid bar(Figure 5.16B).Rastogi, Singh, and Singh (1998c) found hyphae of C. traversiana in the seedcoat and tissues of the hilar region in moderately infected seeds of Trigonella foenumgraecum.Abundant hyphae occurred in the seed coat, endosperm, and embryo inseverely infected seeds. Singh (1991) has reported the presence of conidia ofC. personata in the shells of groundnut, but there is no histopathological evidencefor this.5.5.4.1.6 BotrytisBotrytis anthophila, which causes anther mold of Trifolium pratense (red clover),reduces pollen fertility and also seed formation. Bondarzew (1914) and Silow (1933)reported systemic infection of plants. The infection originated from intraseminalmycelium, particularly present in the hourglass cells of the seed coat. Using seedsincubated on agar for 3 to 5 days, Bennum (1972) observed predominantly intercellularand rarely intracellular mycelium in the seed coat and hilar region — remnantsof funiculus, tracheid bar, and aerenchyma (stellate parenchyma) — but not in theembryo.Botrytis fabae occurs in the seed coat, cotyledons, and embryonal axis in infectedseeds of Vicia faba. Hyphae are present in the seed coat of all the infected seeds,but these occur in 40% of cotyledons and 20% of embryonic axes (Harrison, 1978).Van der Spek (1965) has reported Botrytis cinerea in the cells of seed coat in flax.5.5.4.1.7 PyriculariaPyricularia oryzae causes the most destructive and widely distributed blast diseasein rice. Chung and Lee (1983) have reported infection of P. oryzae within the tissuesof the glumes, rachilla, pedicel, palea, lemma, and pericarp. In heavily infectedseeds, the mycelium penetrates the aleurone layer and peripheral layers of theendosperm. The affected layers of endosperm turn dark brown. The embryos arefree of infection. Earlier, Suzuki (1930, 1934) had reported that seeds from earsartificially inoculated before, during, and after the flowering period, carried thefungal hyphae in the endosperm and embryo.The seeds of Eleusine coracona infected by Pyricularia grisea are asymptomaticand symptomatic (discolored). The discolored seeds exhibited two to three timeshigher infection than the asymptomatic seeds. Pericarp of all the infected seeds had
138 Histopathology of Seed-Borne InfectionspalhgctbpcABscendembCDendembFEFIGURE 5.16 Distribution of fungal mycelium of Cercospora sojina and Macrophominaphaseolina in seeds of Glycine max (A, B) and Sesamum indicum (C to F), respectively. A, Tsseed showing hyphae and hyphal aggregations (arrows) in palisade layer, hourglass cells, andin parenchyma. B, Enlarged region of hilar tracheids showing hyphae. C, Ts seed showingmicrosclerotia in seed coat and endosperm. D, E, Whole-mount preparations of seed coat andendosperm respectively, having thick, knotty, and branched mycelium and microsclerotia.F, Ts part of seed with mycelium in endosperm and its spread to the embryo. (Abbreviations:emb, embryo; end, endosperm; hgc, hourglass cells; pal, palisade cells; pc, parenchymatouscells; sc, seed coat; tb, tracheid bar.) (A, B, From Singh, T. and Sinclair, J.B. 1985. Phytopathology,75, 185–189. With permission; C to F, Singh, T. and Singh, D. 1979. In RecentResearch in Plant Science. Bir, S.S., Ed. Kalyani Publishers, New Delhi.)
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Histopathology ofSeed-Borne Infecti
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PrefaceThe book deals with only one
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The AuthorsDalbir Singh, Ph.D., for
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ContentsChapter 1 Introduction ....
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4.3.2 Routes for Infection from Ova
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8.4 Survival in Seed ..............
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2 Histopathology of Seed-Borne Infe
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4 Histopathology of Seed-Borne Infe
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2Reproductive Structuresand Seed Fo
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Reproductive Structures and Seed Fo
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14 Histopathology of Seed-Borne Inf
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3Structure of SeedsThe seed habit i
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Structure of Seeds 49(1971) of usin
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Structure of Seeds 51is found in as
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Structure of Seeds 53dry seed of Ly
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Structure of Seeds 553.3.2 SEED COA
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Structure of Seeds 57Endosperm: One
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Structure of Seeds 59scendembepsmuA
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Structure of Seeds 61Endosperm: Sca
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Structure of Seeds 63Chalaza simple
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Structure of Seeds 65stystypmerA Bc
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Structure of Seeds 67epsent endCADB
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Structure of Seeds 69perhscendembpe
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Structure of Seeds 71eposgepi′epo
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Structure of Seeds 73(Zea and Sorgh
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Structure of Seeds 75Baker, D.M. an
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Structure of Seeds 77Maheshwari Dev
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Structure of Seeds 79Vries, M.A. de
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188 Histopathology of Seed-Borne In
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7Seed Infection by VirusesViruses a
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Seed Infection by Viruses 201TABLE
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Seed Infection by Viruses 205Unlike
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Seed Infection by Viruses 2073. The
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Seed Infection by Viruses 209Wilcox
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Seed Infection by Viruses 213floret
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Seed Infection by Viruses 215ptowvv
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Seed Infection by Viruses 2177.4.2
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Seed Infection by Viruses 219seed(s
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Seed Infection by Viruses 221AMV fo
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Seed Infection by Viruses 223REFERE
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Seed Infection by Viruses 225Hunter
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Seed Infection by Viruses 227Wolf,
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