Induction of trehalose in spores of the biocontrol agent Trichoderma harzianum

Abstract

Spores of the biocontrol agent Trichoderma harzianum P1 produced in liquid media and harvested in the stationary sporulation stage SSS (after 60 h), had higher viability after slow (>4´) and fast drying (>12´) than their counterparts harvested in the exponential sporulation stage, ESS (after 30 h). The trehalose content of SSS spores was almost 20´higher than that of ESS spores (0.16 vs. 3.4 mg/100 mg, respectively). Heat shock (40°C´90 min) effectively increased the trehalose content 2.5´with respect to untreated SSS spores. The trehalose content achieved in heat-treated SSS spores was almost 60% higher than the maximum reached by holding the spores under water-stress at 97% relative humidity prior to drying. List of symbolsAw Water activity ( RH/100). SSS Stationary sporulation stage ESS Exponential sporulation stage SD Slow drying FD Fast drying SDC(24) Slow drying with conditioning at Aw 0.97 for 24 hours. SDC(48) Slow drying with conditioning at Aw 0.97 for 48 hours. SDC(72) Slow drying with conditioning at Aw 0.97 for 72 hours. FDC(0) Fast drying without conditioning at Aw 0.97. FDC(24) Fast drying with conditioning at Aw 0.97 for 24 hours. FDC(48) Fast drying with conditioning at Aw 0.97 for 48 hours. FDC(72) Fast drying with conditioning at Aw 0.97 for 72 hours. RH Relative humidity (%).

Selection of high temperature and salinity tolerant Trichoderma isolates with antagonistic activity against Sclerotium rolfsii

“…Studies have shown that mannose constitutes 10–15% of dry weight of filamentous fungi and aids in abiotic stress tolerance (Ruijter et al 2003 ). Our results were in accordance with the observation of Pedreschi et al 1997 , who observed the increased accumulation of trehalose in conidia of Trichoderma harzianum P1 on heat shock at 40°C for 90 min. The role of trehalose in fungal survival and as stabilizing agent of cell structures and cellular proteins under heat stress conditions was well investigated (Fillinger et al 2001 ; Ruijter et al 2003 ).…”

“…In the present investigation, high temperature and salinity tolerant Trichoderma strains were isolated from natural soils and their biocontrol efficacy was evaluated. The study also focused on the biochemical estimation of stress protectants and polyols that are known to confer stress tolerance in fungi and plants (Pennycooke et al 2004 ; Ruijter et al 2003 ; Fillinger et al 2001 ; Pedreschi et al 1997 ). As studies have reported the effect of culture age on high temperature tolerance of fungi (Arif Mahmud and Ohmasa 2008 ), measures were taken to identify the optimum culture age of the stress-tolerant isolates identified in the study.…”

Biochemical characteristics ofTrichoderma atrovirideassociated with conidium fitness for biological control

“…For example, high concentrations of linoleic acid (18:2 c9, 12) have been related to increased membrane sensitivity to peroxidation and cellular senescence (May & McCay, 1968;Mowri et al, 1984), while the percentage of unsaturated fatty acid content of Trichoderma conidia in the present study, and also in that of Agosin et al (1997), was not found to be correlated with long term stability. In general, most of the tested conidia contained similar amounts of linoleic acid and also high levels of unsaturation, at least for conidia produced from the growth treatments of 20°C-Dex (60% unsaturation) or 30°C (59% unsaturation).…”

“…Induction of trehalose was not solely correlated to heat shock (as has been demonstrated by Pedreschi et al, 1997) or external trehalose addition (as has been demonstrated by Kets & de Bonts, 1994;Kets et al, 1996;Pedreschi et al, 1997;Bonaterra et al, 2005). Elevated levels were also recorded for some other conidia, such as those from the C:N 160:1 and pH 7.5 production treatments (Table 2).…”

“…Levels of intracellular accumulation of trehalose have also been attributed to the survival and degree of stress resistance (Hottiger et al, 1987;Hounsa et al, 1998). Accumulation of trehalose has been suggested to be induced by stress and does not normally increase in fungal conidia under steady-state culture conditions (Pedreschi et al, 1997). Furthermore, it has been proposed that synthesis of trehalose depends on the presence of mannitol as one of the most common polyols in microorganisms, so that a mixture of trehalose and mannitol is reported to be needed for stress tolerance (Dijksterhuis & de Vries, 2006).…”