Abstract
Trichoderma hamatum strain GD12 is unique in that it can promote plant growth, activate biocontrol against pre- and post-emergence soil pathogens and can induce systemic resistance to foliar pathogens. This study extends previous work in lettuce to demonstrate that GD12 can confer beneficial agronomic traits to other plants, providing examples of plant growth promotion in the model dicot, Arabidopsis thaliana and induced foliar resistance to Magnaporthe oryzae in the model monocot rice. We further characterize the lettuce-T. hamatum interaction to show that bran extracts from GD12 and an N-acetyl-β-D-glucosamindase-deficient mutant differentially promote growth in a concentration dependent manner, and these differences correlate with differences in the small molecule secretome. We show that GD12 mycoparasitises a range of isolates of the pre-emergence soil pathogen Sclerotinia sclerotiorum and that this interaction induces a further increase in plant growth promotion above that conferred by GD12. To understand the genetic potential encoded by T. hamatum GD12 and to facilitate its use as a model beneficial organism to study plant growth promotion, induced systemic resistance and mycoparasitism we present de novo genome sequence data. We compare GD12 with other published Trichoderma genomes and show that T. hamatum GD12 contains unique genomic regions with the potential to encode novel bioactive metabolites that may contribute to GD12's agrochemically important traits.
Highlights
With the global population estimated to reach 9 billion by 2050, current plant breeding approaches alone will not support the increased demand for food
To demonstrate the broad utility of GD12 as an experimental system we extend previous work to show (i) GD12 induced PGP of Arabidopsis thaliana, (ii) GD12 mycoparasitized isolates of the pre-emergent soil pathogen, Sclerotinia sclerotiorum and this antagonistic interaction resulted in further enhanced lettuce PGP, (iii) PGP of lettuce by sterile bran extracts from GD12 which is further enhanced by extracts from the GD12 N-acetyl-β-D-glucosaminidase deficiency mutant, (iv) clear differences in GD12 and the N-acetyl-βD-glucosaminidase deficient mutant secretome fingerprint which may account for the difference in biocontrol and PGP and (v) induction of induced systemic resistance in rice to rice blast by both GD12 and the N-acetyl-β-D-glucosaminidase deficiency
Here we extend our initial characterization of T. hamatum strain GD12 (Ryder et al, 2012) to examine further beneficial agronomic traits of GD12
Summary
With the global population estimated to reach 9 billion by 2050, current plant breeding approaches alone will not support the increased demand for food. Hazard-based criteria for assessing pesticides could lead to a range of agrochemicals being withdrawn from European markets, leading to the potential loss of the only effective fungicide groups against major crop diseases. These challenges have lead to research into alternative sustainable agricultural strategies, with a strong focus on exploiting beneficial organisms. Members of the fungal genus Trichoderma have the potential for reducing existing dependence on the use of environmentally damaging and unsustainable chemicals required for disease control and fertilizers (Fantke et al, 2012), by providing an opportunity to sustainably improve crop productivity while reducing the likelihood of development of fungicide resistant pathogens
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