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Fruit ripening is characterized by processes that modify texture and flavor but also by a dramatic increase in susceptibility to necrotrophic pathogens, such as Botrytis cinerea. Disassembly of the major structural polysaccharides of the cell wall (CW) is a significant process associated with ripening and contributes to fruit softening. In tomato, polygalacturonase (PG) and expansin (Exp) are among the CW proteins that cooperatively participate in ripening-associated ON disassembly. To determine whether endogenous CW disassembly influences the ripening-regulated increase in necrotropic pathogen susceptibility, B. cinerea susceptibility was assessed in transgenic fruit with suppressed polygalacturonase (LePG) and expansin (LeExp1) expression. Suppression of either LePG or LeExp1 alone did not reduce susceptibility but simultaneous suppression of both dramatically reduced the susceptibility of ripening fruit to B. cinerea, as measured by fungal biomass accumulation and by macerating lesion development. These results demonstrate that altering endogenous plant CW disassembly during ripening influences the course of infection by B. cinerea, perhaps by changing the structure or the accessibility of CW substrates to pathogen CW-degrading enzymes. Recognition of the role of ripening-associated CW metabolism in postharvest pathogen susceptibility may be useful in the design and development of strategies to limit pathogen losses during fruit storage, handling, and distribution. expansin | polygalacturonase | tomato | plant pathogen

Research concerning microtiter immunospore trapping device is presented. The use of this device for detection and immunoquantification of Mycosphaerella brassicicola ascospores and Botrytis cinerea conidia is discussed.

The mycelium of Anguillospora longissima grown on the decomposing leaf material is diagnosed both in vitro and in vivo by immunofluorescence, enzyme-linked immunosorbent assay and immunoenzymatic staining processes using the monoclonal antibody AL-HH8c. At any age and culture conditions of the mycelial, the AL-HH8c identifying antigens are obtained.

Examines the efficacy of immunomonitoring air-borne fungal plant pathogens. Containment of Mycosphaerella brassicicola of pseudothecia; Time of release of the ascospores; Integration of immunofluorescence test with monoclonal antibody for accurate detection of ascospores.

Immunoelectron microscopy using the anti-pectin monoclonal antibody JIM 7 confirmed earlier observations that pectin degradation is a primary event in the process of host cell wall breakdown during the development of chocolate spot disease (causal agent: Botrytis fabae (Sard.)) of broad bean. Close examination of infected and non-infected Vicia faba L.. leaves indicated a loss of JIM 7-labeling, and therefore, methyl-esterified pectin, from swollen walls of infected and contiguous epidermal cells. Modified mesophyll walls also possessed less methyl-esterified pectin than healthy walls. Enzymes which attack methyl-esterified pectin appeared to he most active in regions of host tissue close to sites of fungal infection. Ultrastructural studies using the enzyme, cellobiohydrolase conjugated to gold (CBH1-Au) revealed that the cellulose microfibrils of outer epidermal walls of non-infected V. faba leaf tissue were heavily masked by other components of the plant cell wall. Such material was most probably pectin because the cellulose microfibrils of swollen epidermal and modified mesophyll walls of infected host tissue were heavily labelled with CBH1-Au. These results were confirmed by double-labeling studies using JIM 7 and CBH1-Au. At early stages of the infection process, limited cellulose degradation was observed in infected leaf tissue. Double-labelling experiments using the monoclonal antibody BC-KH4 directed against Botrytis matrices and a marker for the plant cell wall (JIM 7 or CBH1-Au) confirmed previous observations that the fungal matrices extended through modified host walls and degenerate cytoplasm. It is suggested that the wall-modifying action of the pectin-degrading enzymes produced during the infection process might facilitate pervasion of matrix material associated with the infection process might facilitate pervasion of matrix material associated with the infection hyphae through host cell walls. ossible role(s) of such matrix material during the post-penetration rocesses of the V. faba-B. fabae relationship are discussed. [ABSTRACT FROM AUTHOR]