Histopathology of longleaf pine needles infected by Ploioderma hedgcockii (Dearn.) Darker

Abstract

The histopathology of Ploioderma hedgcockii on longleaf pine needles was examined. Abnormal host tissue was confined to the visible lesion and to tissues external to the endodermis where collapse ot niesophyll cells was the predominant abnormality. Resin ducts exhibited necrosis and dissolution of epithelial cells. 1 Hypnae, intra-and intercellular, were frequent to profuse in intercellular spaces resulting from mesophyll cell collapse. Hyphae were external to the endodermis and appeared limited to the symptomatic tissue by an intercellular matrix at the lesion boundaries. Hysterotheca were subepidermal and appeared seated on the hypodermis. Asci appeared to contain four "two-stage" ascospores. The presence of a toxin was not indicated in the host/ pathogen relationship.

Histopathology of Pinus taeda needles infected by Ploioderma lethale

“…Microscopically, Pinus taeda needle tissue affected by P. lethale exhibited anatomical abnormalities similar to reports for other Southern pine needle‐cast pathogens ( J EWELL 1983 , 1990a, b, 1994). The collapse of mesophyll cells resulting in the typical ‘lattice‐like’ appearance of these cells was again the prominent anatomical abnormality exhibited in P. lethale ‐affected needle tissue.…”

“…2A,B). Cell abnormalities usually associated with the presence of needle‐cast pathogen hyphae were not observed in the colonized noncollapsed mesophyll cells ( H ARTIG 1874 ; J EWELL 1983 , 1990a, b, 1993a, 1994, 1998).…”

A review of Pinaceae resistance mechanisms against needle and shoot pathogens with a focus on the Dothistroma–Pinus interaction

“…The matrix may provide a physical barrier in needle tissue to prevent the pathogen from advancing into healthy tissue. Jewell (1990) reported similar observations in P. hedgcockii-infected P. palustris needles; however, no hypertrophy or hyperplasia was observed, nor invasion of the endodermis. In both cases, hyphae grew extensively in diseased tissue, but were not observed in or beyond the matrix into healthy tissue.…”

“…White pine blister rust P. strobus Woo et al (2001) D. septosporum Dothistroma needle blight P. radiata Franich et al (1977) Defences acting post-penetration Jewell (1990) This study reviews the current knowledge of resistance mechanisms that may play a role in the Dothistroma-Pinus pathogen-host system. In section 'Resistance mechanisms involved in the Dothistroma-Pinus system and other similar pathogen-host interactions', the mechanisms shown to be involved in the defence of Pinaceae against needle and shoot pathogens are discussed.…”

“…laricio needles infected with L. sulcigena and in P. palustris needles infected with Ploioderma hedgcockii (Dearn.) Darker (Williamson et al 1976;Jewell 1990). Williamson et al (1976) reported that prior to hypertrophy and hyperplasia of cells at the host-parasite interface in L. sulcigena-infected P. nigra ssp.…”