For example, though Andrade-Linares Protein Tyrosine Kinase inhibitor et al. (2011) did not measure antioxidant or reactive oxygen species production they reported a potential negative, life stage response of the host to FK228 ic50 endophyte colonization. In their study three dark septate endophyte species colonizing tomato (Lycopersicum esculentum) successfully decreased the negative effects of the fungal pathogen Verticillium dahlia but only when the pathogen was presented in low doses. At higher pathogen doses the endophyte effect on host biomass loss was not significantly different from controls. The same study found no significant difference

in terms of reproductive output between E + and E- plants except at the earliest harvest date. Fruit number and biomass at first harvest were significantly higher in E + versus E- hosts. Thus positive impacts on host vegetative growth and reproductive output appear to be life stage dependent, but whether they extend to increased host lifetime fitness has not been determined. Shoot and whole plant endophytes

Several studies on various host species and their shoot associated fungal endophytes support increased host stress tolerance due to increased antioxidant production in E + hosts (Table 1) compared to E- hosts. A comparison of cellular level reactive oxygen species scavenging activity in Phyllosticta colonized versus E- Guazuma tomentosa revealed significantly higher scavenging activity in the former (Srinivasan E7080 in vivo et al. 2010). Neotyphodium–endophyte colonized grasses showed significantly higher glutamine synthetase and total amino acid activity (Lyons et al. 1990) in response to nutrient treatments which positively correlated with host biomass. In response to temperature, ID-8 drought, and salt stress, E + hosts produced significantly more biomass than their E- counterparts (Redman et al. 2001 and 2002; Márquez et al. 2007; Rodriguez et al. 2008; Redman et al. 2011). Regardless of plant host or fungal endophyte genera, symbiosis resulted in increased plant biomass production

and/or survival in response to all three stress treatments and the mechanism appeared to be increased antioxidant activity leading to higher reactive oxygen species scavenging rates and lower reactive oxygen species accumulation in E + host tissues (Rodriguez et al. 2008). This leads to the general conclusion that habitat-specific stress tolerance can be effectively conferred via symbiotic interactions with fungal endophytes from diverse genera (Rodriguez et al. 2008). Additional studies reported a virus present in the endophyte Curvularia protuberata was needed for the endophyte to confer heat tolerance (Márquez et al. 2007). Both a monocot and dicot colonized by the virus-endophyte combination were able to successfully tolerate root zone temperatures of up to 65°C.