Classical and augmentative biological control against ... - IOBC-WPRS

Ruocco et al.
A fundamental part of the Trichoderma antifungal capability consists in the production and
secretion of a great variety of extracellular cell wall degrading enzymes (CWDEs), including
endochitinases, β-N-acetylhexosaminidase (N-acetyl-β-D-glucosaminidase), chitin-1,4-β-chitobiosidases,
proteases, endo- and exo-β-1,3-glucanases, endo β-1,6-glucanases, lipases, xylanases,
mananases, pectinases, pectin lyases, amylases, phospholipases, RNAses, DNAses, etc. (Benitez et
al. 2004; Lorito et al. 1998). The chitinolytic and glucanolytic enzymes are especially valuable for
their CWDE activity on fungal plant pathogens, hydrolyzing polymers not present in plant tissues
(Woo et al. 1999). Each of these classes of enzymes contains diverse sets of proteins with distinct
enzymatic activities. Some have been purified, characterized and their encoding genes cloned (Ait-
Lahsen et al. 2001; de la Cruz et al. 1992; 1995a; 1995b; Garcia et al. 1994; Limon et al. 1995;
Lora et al. 1995; Lorito et al. 1993,. 1994b; Montero et al. 2007; Peterbauer et al. 1996; Suarez et
al. 2004; Viterbo et al. 2001, 2002). Once purified, many Trichoderma enzymes have shown to
have strong antifungal activity against a wide variety of phytopathogens, and they are capable of
hydrolyzing not only the tender young hyphal tips of the target fungal host, but they are also able to
degrade the hard, resistant conservation structures such as sclerozi.
Trichoderma spp. have been widely studied, and are presently marketed as biopesticides,
biofertilizers and soil amendments, due to their ability to protect plants, enhance vegetative growth
and contain pathogen populations under numerous agricultural conditions (Harman 2000, 2004;
Vinale et al. 2008b). The commercial success of products containing these fungal antagonists can
be attributed to the large volume of viable propagules that can be produced rapidly and readily on
numerous substrates at a low cost in diverse fermentation systems. The living microorganisms,
conserved as spores, can be incorporated into various formulations, liquid, granules or powder etc.,
and stored for months without losing their efficacy (Jin et al. 1996). To date more than 50 different
Trichoderma-based preparations are commercialized and used to protect or increase the
productivity of numerous horticultural and ornamental crops (Table 13; Lorito et al. 2006).
The case Trichoderma: mode of application, persistence on the target and new
formulations.
Effectiveness under controlled conditions (even under field conditions) does not necessarily
guarantee that the organism will perform successfully; proper formulation is a prime condition for
meeting market requirements. For instance an efficient biocontrol agent of soilborne and airborne
pathogens must first and foremost protect the young seedling against detrimental attack by infective
inoculum. Therefore some factors may be considered:
(a) soil ecosystem factors such as moisture, pH, structure, and temperature;
(b) root colonization capacity;
(c) reasonable shelf life;
(d) efficiency of application of the biocontrol agent in terms of its specific habitat and target
(Spiegel and Chet 1998)
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