Cytochemical localization and ultrastructure of Aspergillus flavus in cottonseed

Aspergillus flavus: the major producer of aflatoxin

“…The fungus does not appear to enter through the stigma, but rather enters from nectaries or other natural openings below the ovary and then moves upward into the developing boll (Klich and Chmielewski, 1 985; Klich et al ., 1984, 1986). Ultrastructural evidence indicates that the fungus may be entering the seeds via the vascular tissue (Huizar et al ., 1990). Early season bolls and those under water stress (water potentials between –1.6 and –1.9 MPa) at anthesis are more susceptible to infection than later season bolls or those under more or less stress at anthesis (Klich, 1987, 1990).…”

Development of a GFP-Expressing Aspergillus flavus Strain to Study Fungal Invasion, Colonization, and Resistance in Cottonseed

“…After analyzing cotton plants inoculated at cotyledonary leaf scars, unopened flower buds, and involucral nectaries or the peduncle of newly opened flowers for aflatoxin contamination in cotton bolls, Klich and her colleagues [6][7][8] concluded that the fungus might gain entry through the vascular bundles, primarily through xylem vessels. Hamsa and Ayres [9] observed that hyphal invasion in stored cottonseeds proceeded via chalaza, micropyle, and cracks that developed in the seed coat during ginning.…”

“…Hamsa and Ayres [9] observed that hyphal invasion in stored cottonseeds proceeded via chalaza, micropyle, and cracks that developed in the seed coat during ginning. Likewise, after microscopic analyses of contaminated cottonseeds, Lee et al [10] and Huizar et al [8] hypothesized that the fungus may enter through nonlignified layers of the seed coat. However, clear evidence regarding entry of the fungus and the infection process during pre-or post-harvest phases of contamination has not been available from these studies.…”