title: Environmental Growth Conditions ofTrichodermaspp. Affects Indole Acetic Acid Derivatives, Volatile Organic Compounds, and Plant Growth Promotion.
abstract: Trichodermaspecies are soil-borne filamentous fungi widely utilized for their many plant health benefits, such as conferring improved growth, disease resistance and abiotic stress tolerance to their hosts. ManyTrichodermaspecies are able to produce the auxin phytohormone indole-3-acetic acid (IAA), and its production has been suggested to promote root growth. Here we show that the production of IAA is strain dependent and diverse external stimuli are associated with its production. Inin vitroassays,Arabidopsisprimary root length was negatively affected by the interaction with someTrichodermastrains. In soil experiments, a continuum effect on plant growth was shown and this was also strain dependent. In plate assays, some strains ofTrichodermaspp. inhibited the expression of the auxin reporter gene DR5 inArabidopsisprimary roots but not secondary roots. WhenTrichodermaspp. andA. thalianawere physically separated, enhancement of both shoot and root biomass, increased root production and chlorophyll content were observed, which strongly suggested that volatile production by the fungus influenced the parameters analyzed.TrichodermastrainsT. virensGv29.8,T. atrovirideIMI206040,T. sp. "atroviride B"LU132, andT. asperellumLU1370 were demonstrated to promote plant growth through volatile production. However, contrasting differences were observed with LU1370 which had a negative effect on plant growth in soil but a positive effect in plate assays. Altogether our results suggest that the mechanisms and molecules involved in plant growth promotion byTrichodermaspp. are multivariable and are affected by the environmental conditions.
authors.affiliation: Bio-Protection Research Centre, Lincoln University Lincoln, New Zealand.
authors.forename: Maria F
authors.initials: MF
authors.lastname: Nieto-Jacobo
authors.affiliation: Bio-Protection Research Centre, Lincoln University Lincoln, New Zealand.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Steyaert
authors.affiliation: Bio-Protection Research Centre, Lincoln UniversityLincoln, New Zealand; Institute for Scientific and Technological Research of San Luis PotosiSan Luis Potosí, Mexico.
authors.forename: Fatima B
authors.initials: FB
authors.lastname: Salazar-Badillo
authors.affiliation: Bio-Protection Research Centre, Lincoln University Lincoln, New Zealand.
authors.forename: Dianne Vi
authors.initials: DV
authors.lastname: Nguyen
authors.affiliation: Bio-Protection Research Centre, Lincoln University Lincoln, New Zealand.
authors.forename: Michael
authors.initials: M
authors.lastname: Rostás
authors.affiliation: Bio-Protection Research Centre, Lincoln University Lincoln, New Zealand.
authors.forename: Mark
authors.initials: M
authors.lastname: Braithwaite
authors.affiliation: Bio-Protection Research Centre, Lincoln UniversityLincoln, New Zealand; Department of Phytopathology, Federal University of LavrasLavras, Brazil.
authors.forename: Jorge T
authors.initials: JT
authors.lastname: De Souza
authors.affiliation: Institute for Scientific and Technological Research of San Luis Potosi San Luis Potosí, Mexico.
authors.forename: Juan F
authors.initials: JF
authors.lastname: Jimenez-Bremont
authors.affiliation: School of Plant Sciences, University of Arizona Tucson, AZ, USA.
authors.forename: Mana
authors.initials: M
authors.lastname: Ohkura
authors.affiliation: Scion Rotorua, New Zealand.
authors.forename: Alison
authors.initials: A
authors.lastname: Stewart
authors.affiliation: Bio-Protection Research Centre, Lincoln University Lincoln, New Zealand.
authors.forename: Artemio
authors.initials: A
authors.lastname: Mendoza-Mendoza
keywords: 3-indole-acetic acid; 6-PP; Trichoderma; auxins; plant growth promotion; volatile organic compounds