Gigaspora albida

WHOLE SPORES

COLOR: Opaque white to pale yellow (0/0/15/0) with pale green tint (5/0/20/0)

SHAPE: Globose to subglobose.

SIZE DISTRIBUTION: 220-360 µm, mean = 290 µm (n = 96).

SUBCELLULAR STRUCTURE OF SPORES

SPORE WALL: Formed by three layers (C1, C2 and C3 in the photos). C1 and C2 are adherent and of equal thickness in juvenile spores, with the laminated layer thickening as the spore wall differentiates. Layer 3 (C3) differentiates as requirement to the germ tube formation (Bentivenga & Morton 1995).

C1: An outer permanent rigid layer, hyaline (0-0-10-0), smooth, with 1.0-2.0 µm thick (mean 1,7 µm). This layer is firmly attached to C2.

C2: A layer consisting of sublayers (or laminae), cream yellowish (0/10/80/0); 5-18 µm (mean 12 µm). Sublayers of this layer are semi-plastic and they vary in thickness in mature spores (7 to 14 µm). This layer reacts in Melzer’s reagente turning dark red-brown (20-80-100-0); Melzer’s reaction seems not to be uniform and some areas reacts more than others within the same spore, resulting in dark circular areas in some spores.

C3: A germinal layer, very thin (1-2 µm thick), with many folds and firmly attached to C2. Numerous “warts” or “papillae” are formed in this layer previously to spore germination. These warts tend to be concentrated in regions near the suspensor cell.

SUBTENDING HYPHA

WIDTH OF SPOROGENOUS CELL: 31-55 µm (mean = 42 µm).

SPOROGENOUS CELL WALL: Possible formed by two layers (C1 and C2) which are continuous with layers 1 and 2 of the spore wall. However, only laminated layer 2 is easily discernible at the compound microscope.

C2: Pale yellow (0/10/80/0) and concolour with C2 of the spore wall, 2-4 µm thick near the spore and then thinning (0.5 µm) beyond the sporogenous cell.

SEPTUM: Subtending hypha that originates the sporogenous cell regularly septated. Septa were observed in the subtending hypha up to 200 µm from the spore base.

OCCLUSION: Closure by a plug concolorous with the laminated C2 of the spore wall.

Comparison with Original Description

Color:

Description: Dull white with a light greenish-yellow.

SCT200A: Dull white to pale yellow with pale green tint

Form:

Description: Mostly spherical, occasionally ellipsoidal

SCT200A: Globose to subglobose

Size:

Description: 143-330 (-350 µm). Mean 265 µm

SCT200A: 220-360 µm, mean = 290 µm

Spore Wall: C1

Description: Thin, smooth, 1-2 µm thick

SCT200A: Thin, smooth, 1-2 µm (mean 7 µm)

Spore Wall: C2

Description: Usually 2 or 3 but occasionally 4-5 “inner walls” . Description brings only the total thickness of the spore wall and it does not inform the thickness of C2.

SCT200A: Varying considerably in thickness (5-18 µm; mean = 12 µm).

Spore Wall: C3

Description: Not informed

SCT200A: Thin, with warts, 1-2 µm.

Sporogenous Cell

Description: Hialine to yellow, (24-) 36 (-50) µm.

SCT200A: Pale yellow, 31-55 µm, mean = 42 µm

Taxonomic History

Manuscript: Schenck, N.C. and G.S. Smith (1982). Additional new and unreported species of Mycorrhizal fungi (Endogonaceae) from Florida. Mycologia 77(4):566-574.

Etymology: Latin (albida = whitish) referring to the spore color.

Type: spores from pot cultures with Paspalum notatum established with soil from soybean rhizosphere on the Agronomy Farm, Univ. of Florida, Gainesville. Type OSC No. 40.250; Isotype FH, FLAS No. F5579.

Biogeography

Gigaspora albida is a cosmopolitan species, detected in all continents, except Antarctica and Europe, present in 11 countries, occurring in tropical, subtropical, temperate regions and with one record from the boreal region. Gigaspora albida was detected in several ecosystems like sand dunes (Stürmer & Bellei 1994) and agroecosystems (Hetrick et al. 1984), and in biomes like Deserts (Dhillion et al. 1995), Temperate Grasslands (Bentivenga & Hetrick 1992), Temperate Forests (Johnson et al. 1991), Tropical and Subtropical Savannas (Uhlmann et al. 2004), Xeromorphic Forests (Yano Melo et al. 2003).

The map below shows countries (in red) where Gigaspora albida was detected.

References:

Bentivenga, S.P. and B.A.D. Hetrick (1992). The effect of prairie management practices on mycorrhizal symbiosis. Mycologia, 84:522-527.

Bentivenga, S.P. and J. B. Morton (1995). A monograph of the genus Gigaspora, incorporating developmental patterns of morphological characters. Mycologia 87: 720-732.

Dhillion, S.S., P.E. Vidiella, L.E. Aquilera, C.F. Friese, E. De Leon, J.J. Armesto and J.C. Zak (1995). Mycorrhizal plants and fungi in the fog-free pacific coastal desert of Chile. Mycorrhiza 5:381-386.

Hetrick, B.A.D.; J.A. Hetrick and J. Bloom (1984). Interactions of mycorrhizal infection, phosphorus level, and moisture stress in growth of field corn. Can. J. Bot., 62:2267-2271.

Johnson, N.C.; D.R. Zak; D. Tilman and F.L. Pfleger (1991). Dynamics of vesicular-arbuscular mycorrhizae during old field succession. Oecologia, 86:349-358.

Schenck, N.C. and G.S. Smith (1982). Additional new and unreported species of Mycorrhizal fungi (Endogonaceae) from Florida. Mycologia 77(4):566-574.

Uhlmann, E., C. Gorke, A. Petersen and F. Oberwinkle (2004). Arbuscular mycorrhizae from semiarid regions of Namibia. Can J Bot 82:645-653.

Yano-Melo, A.M., S.F.B. Trufem and L.C. Maia (2003). Arbuscular mycorrhizal fungi in salinized and surrounded areas at the São Francisco Submedium Valley, Brazil. Hoehnea, 30:79-87.

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