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

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Physiogenic or Nonpathogenic Seed Disorders 2499.1 MINERAL NUTRIENT DEFICIENCYThe deficiency in soil of a number of major or micronutrients leads to the developmentof visible symptoms in seeds (Table 9.1). The symptoms may be exomorphic,caused externally, e.g., yellow berry of wheat, tapering seeds in cucumber, anddistorted seeds of Vicia faba due to the deficiency of nitrogen, potassium, and zinc,respectively, or endomorphic (internal), mostly seen on the adaxial surface of cotyledons,namely marsh spot of peas and beans, and hollow heart in groundnut causedby the deficiency of manganese and boron, respectively. The use of the term hollowheart for the disorder in groundnut is a misnomer since this term is widely used foran anomaly caused in peas due to low atmospheric humidity at the time of thematurity of the crop. Detailed histopathological information is available only on peaseeds showing marsh spot.9.1.1 MARSH SPOT IN PEASMarsh spot is characterized by discolored brown areas in the center of the adaxialface of the cotyledons (Figure 9.1A, affected cotyledons [right] and normal [left]).The disorder was first described by Mansholt in 1894 and later observed in theNetherlands (De Bruijn, 1933), Britain (Lacey, 1934), and Finland (Jamalainen,1936). It is common in peas grown in Romney Marsh, England, and in newlyreclaimed sea silt soils of the Netherlands (Noble, 1960). Singh (1974) detectedmarsh spot in seeds of smooth seeded cultivars, namely Diktron, Marrow (theNetherlands) and Feltham First (Scotland). Manganese deficiency in soil is shownto be the cause of this disorder (De Bruijn, 1933; Löhnis, 1936; Pethybridge, 1936;Heintze, 1938, 1956; Cuddy, 1959), and manganese sulphate as a measure of controlwas established by these authors.Wallace (1951) has figured brown lesion on adaxial surface of cotyledons, similarto marsh spot, in broad bean, harricot bean and runner bean. He also attributes thisdisorder to manganese deficiency of soil.9.1.1.1 HistologyAnatomically the asymptomatic cotyledons consist of parenchyma cells, which, apartfrom the epidermis, are all polygonal (Figure 9.1B). None of the mesophyll layersare of the palisade type. Air spaces occur throughout the mesophyll (Figure 9.1B,C). The size and shape of the nuclei show great variations depending upon the sizeof the cell and the amount of the starch grains. The nuclei are hypertrophied, havingdiffused and granular intranuclear contents. An organized nucleus is rarely seen. Thecells contain abundant simple starch grains (Figure 9.1B, C).The affected cotyledons on the adaxial side reveal that the subhypodermal layers,three to four cells deep, show more serious symptoms of derangement. The cellsand intercellular space are enlarged and the cell contents stained deeply with safranin.The cell walls become broad with granular material beneath. The cell contents,including starch grains, show corrosion and secretion of glistening dark brown oilydroplets, which accumulate in intercellular air space (Figure 9.1D, E).
250 Histopathology of Seed-Borne InfectionsABCDEFIGURE 9.1 Photographs of normal and marsh spot-affected cotyledons of pea. A, Cotyledonsshowing adaxial surface from water-soaked split seeds of cultivar Koroza (Holland) —normal (left) and marsh spot affected (right). B to E, Histology of normal and marsh spotaffectedcotyledons of cultivar Feltham First (Scotland). B, Ts part of normal cotyledon fromadaxial side, showing clear air spaces and cells packed with reserve food contents. C, Aportion from B magnified. D, E, Ts parts of marsh spot-affected cotyledon showing accumulationof pigmented material in air spaces (arrows) and depletion of cell contents. (FromSingh, D. 1974. Seed Sci. Technol. 2: 443–456. With permission.)
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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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TABLE 5.6Location of Mycelium of St
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Page 214 and 215: 7Seed Infection by VirusesViruses a
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Page 222 and 223: Seed Infection by Viruses 2073. The
Page 224 and 225: Seed Infection by Viruses 209Wilcox
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Page 230 and 231: Seed Infection by Viruses 215ptowvv
Page 232 and 233: Seed Infection by Viruses 2177.4.2
Page 234 and 235: Seed Infection by Viruses 219seed(s
Page 236 and 237: Seed Infection by Viruses 221AMV fo
Page 238 and 239: Seed Infection by Viruses 223REFERE
Page 240 and 241: Seed Infection by Viruses 225Hunter
Page 242: Seed Infection by Viruses 227Wolf,
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