The Molecular Basis of Shoot Responses of Maize Seedlings to Trichoderma harzianum T22 Inoculation of the Root: A Proteomic Approach  

Abstract

Trichoderma spp. are effective biocontrol agents for several soil-borne plant pathogens, and some are also known for their abilities to enhance systemic resistance to plant diseases and overall plant growth. Root colonization with Trichoderma harzianum Rifai strain 22 (T22) induces large changes in the proteome of shoots of maize (Zea mays) seedlings, even though T22 is present only on roots. We chose a proteomic approach to analyze those changes and identify pathways and genes that are involved in these processes. We used two-dimensional gel electrophoresis to identify proteins that are differentially expressed in response to colonization of maize plants with T22. Up-or down-regulated spots were subjected to tryptic digestion followed by identification using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry and nanospray ion-trap tandem mass spectrometry. We identified 91 out of 114 up-regulated and 30 out of 50 down-regulated proteins in the shoots. Classification of these revealed that a large portion of the up-regulated proteins are involved in carbohydrate metabolism and some were photosynthesis or stress related. Increased photosynthesis should have resulted in increased starch accumulation in seedlings and did indeed occur. In addition, numerous proteins induced in response to Trichoderma were those involved in stress and defense responses. Other processes that were up-regulated were amino acid metabolism, cell wall metabolism, and genetic information processing. Conversely, while the proteins involved in the pathways noted above were generally up-regulated, proteins involved in other processes such as secondary metabolism and protein biosynthesis were generally not affected. Up-regulation of carbohydrate metabolism and resistance responses may correspond to the enhanced growth response and induced resistance, respectively, conferred by the Trichoderma inoculation.

Potential of Trichoderma spp. as Biological Control Agents Against Bakanae Pathogen (Fusarium fujikuroi) in Rice

“…Lytic enzymes of Trichoderma such as cellulases, chitinases, glucanase and proteases are partially induced before direct contact with the host (Foreman et al, 2003). Besides, Trichoderma interaction with plant roots creates a sensitized state in the plant allowing it to respond more efficiently to subsequent pathogenic attack (Shoresh and Harman, 2008). Sharma (2011) demonstrated Trichoderma spp.…”

Functional analysis of non-ribosomal peptide synthetases (NRPSs) in Trichoderma virens reveals a polyketide synthase (PKS)/NRPS hybrid enzyme involved in the induced systemic resistance response in maize

“…During PGPR-mediated induced systemic resistance (ISR), the plants are 'sensitized/primed' (no major metabolic changes occur prior to challenge inoculation by a pathogen) in response to the presence of the bacteria in the root zone (van Wees et al, 1999). In contrast, root colonization by Trichoderma per se induces both priming effects and transcriptomic/metabolic changes in plants, including the triggering of defence response genes encoding enzymes such as phenylalanine ammonia lyase (pal), hydroperoxide lyase (hpl) and allene oxide synthase (aos) (Shoresh & Harman, 2008;Djonović et al, 2007;Vargas et al, 2008;Viterbo et al, 2005;Shoresh et al, 2010;Mastouri et al, 2010). PGPR and Trichoderma-mediated ISR, is different from pathogentriggered systemic acquired resistance (SAR), but both ISR and SAR require NPR1 (non-expressor of pathogenesisrelated genes; Van der Ent et al, 2008).…”

Comparative study of Trichoderma gene expression in interactions with tomato plants using high-density oligonucleotide microarrays

“…(Carpenter et al, 2005;Liu & Yang, 2005;Scherm et al, 2009;Vizcaíno et al, 2006Vizcaíno et al, , 2007. Several researchers have explored the responses of plants to the presence of a root-colonizing Trichoderma strain (Alfano et al, 2007;Marra et al, 2006;Segarra et al, 2007;Shoresh & Harman, 2008), but the fungal component of this association has been less studied. Macroarray analyses have been applied to study the gene expression of four species of Trichoderma during their interaction with cacao seedlings (Bailey et al, 2006), and of Trichoderma harzianum during the early colonization of tomato roots (Chacó n et al, 2007), although one limitation to such studies has been the low number of genes tested.…”