The beneficial endophyte Trichoderma hamatum isolate DIS 219b promotes growth and delays the onset of the drought response in Theobroma cacao

Abstract

Theobroma cacao (cacao) is cultivated in tropical climates and is exposed to drought stress. The impact of the endophytic fungus Trichoderma hamatum isolate DIS 219b on cacao's response to drought was studied. Colonization by DIS 219b delayed drought-induced changes in stomatal conductance, net photosynthesis, and green fluorescence emissions. The altered expression of 19 expressed sequence tags (ESTs) (seven in leaves and 17 in roots with some overlap) by drought was detected using quantitative real-time reverse transcription PCR. Roots tended to respond earlier to drought than leaves, with the drought-induced changes in expression of seven ESTs being observed after 7 d of withholding water. Changes in gene expression in leaves were not observed until after 10 d of withholding water. DIS 219b colonization delayed the drought-altered expression of all seven ESTs responsive to drought in leaves by ≥3 d, but had less influence on the expression pattern of the drought-responsive ESTs in roots. DIS 219b colonization had minimal direct influence on the expression of drought-responsive ESTs in 32-d-old seedlings. By contrast, DIS 219b colonization of 9-d-old seedlings altered expression of drought-responsive ESTs, sometimes in patterns opposite of that observed in response to drought. Drought induced an increase in the concentration of many amino acids in cacao leaves, while DIS 219b colonization caused a decrease in aspartic acid and glutamic acid concentrations and an increase in alanine and γ-aminobutyric acid concentrations. With or without exposure to drought conditions, colonization by DIS 219b promoted seedling growth, the most consistent effects being an increase in root fresh weight, root dry weight, and root water content. Colonized seedlings were slower to wilt in response to drought as measured by a decrease in the leaf angle drop. The primary direct effect of DIS 219b colonization was promotion of root growth, regardless of water status, and an increase in water content which it is proposed caused a delay in many aspects of the drought response of cacao.

Unraveling Trichoderma species in the attine ant environment: description of three new taxa

“…Several other studies with leaf-cutting ants (Atta and Acromyrmex) suggested that Trichoderma fungi are associated with the plant substrate foraged by workers (Barbosa 2004;Rodrigues et al 2008Rodrigues et al , 2009Rodrigues et al , 2011 Samuels et al 2006;Bae et al 2009;Chaverri et al 2011;Druzhinina et al 2012;Bailey and Melnick 2013). Regarding T. viride, this species was considered to be restricted to the north hemisphere and found in soil, trunks and decaying wood, with only two strains reported in the tropics, isolated as endophytes of Theobroma gileri (Ecuador) and Theobroma cacao (Brazil) (Lieckfeldt et al 1999;Jaklitsch et al 2006;Samuels et al 2006).…”

“…Trichoderma is cosmopolitan , occurring on various substrates in different parts of the world, including: (i) soil; (ii) decaying wood; (iii) on edible mushrooms and (iv) as endophytes in plants Hanada et al 2008;Bae et al 2009;Chaverri et al 2011;Druzhinina et al 2012;Bailey and Melnick 2013;. Due to the diversity of substrates collected by attine ants, their colonies represent potential resources for the discovery of new Trichoderma species.…”

Trichoderma gamsii affected herbivore feeding behaviour on Arabidopsis thaliana by modifying the leaf metabolome and phytohormones

“…have beneficial effects on plants. For instance, there are commercial agricultural products containing T. atroviride, T. harzianum and T. hamatum (Ha, 2010) that promote plant growth (Chang et al ., 1986; Gravel et al ., 2007; Contreras‐Cornejo et al ., 2009), reduce the severity of plant diseases (Naseby et al ., 2000; Nawrocka and Malolepsza, 2013) and enhance tolerance to abiotic stresses (Bae et al ., 2009; Montero‐Barrientos et al ., 2010; Dixit et al ., 2011; Contreras‐Cornejo et al ., 2014). In addition, Trichoderma sp.…”

Novel Endophytic Trichoderma spp. Isolated from Healthy Coffea arabica Roots are Capable of Controlling Coffee Tracheomycosis

“…Several epiphytic and endophytic Trichoderma species and strains are already being well studied and further recommended as potential biological control agents against phytophatogenic fungi such as Phytophthora capsici in hot pepper [52], Moniliophthora roreri, M. fide, M. perniciosa, and Phytophthora species in cacao trees [43,53]. Trichoderma strains being studied for their potential to control cacao diseases and ameliorate damage caused by abiotic stresses also have an ability to alter cacao gene expression during colonization [43].…”