CHARACTERIZATION OF A PLANT DEFENSE SUPPRESSOR SECRETED BY Colletotrichum acutatum M11

TOMAS GRAU, RODRIGO HERNÀN; REQUENA SERRA, F. J.; DIAZ-RICCI, J. C.

Tafi del Valle

Encuentro; XXXIV ANNUAL SCIENTIFIC MEETING; 2017

The activation of the defense response in plants is accompanied by several physiological changes that provide them with the capacity to resist pathogen attacks. Among those, the accumulation of reactive oxygen species, cell wall reinforcement, and the induction of pathogenesis-related proteins can be mentioned. AsES is an extracellular subtilisin-like protein that provides strawberry plants with protection against several pathogens. However, when plants were treated simultaneously with AsES and the supernatant of the virulent fungi Colletotrichum acutatum M11 (SN-M11), they acquired the disease, suggesting that a suppressive defense effect occurred. In this work we investigated the biochemical and molecular events involved in the suppression of the defense response. Accordingly, plants were treated with a) AsES, b) SN-M11, c) AsES + SN-M11 and d) H2O. Soluble (SPC) and cell wall-bound phenolic compounds (BPC) were quantified and RNA extraction was performed in order to evaluate gene expression of FaPR1 (Pathogenesis related protein 1), FaCHI23 (Chalcone isomerase 23), FaPRX27 (Peroxidase27) and FaCAT (catalase) at 24, 48, 72 and 144 hours post treatment (hpt) by qPCR. Results showed that plants treated with AsES + SN-M11 exhibited lower expression levels of FaPR1 (72 hpt), FaCHI23 (72 hpt), FaPRX27 (72 and 144 hpt) and less accumulation of SPC and BPC with respect to AsES-treated plants, whereas FaCAT showed a similar behavior at 24 and 144 hpt. These results confirm that SN-M11 suppresses the biochemical and molecular events induced by AsES.