Biology & Biotechnology Virtual Seminar: Dr. Juan Carlos Diaz Ricci
“Fungal pathogens exerting agonistic and antagonistic effects on the innate immunity of strawberry plants"
Prof. Dr. Juan Carlos Diaz Ricci
Principal researcher and director of the Superior institute of biological Sciences (INSIBIO) at the National Scientific and Technological Research Council (CONICET), Argentina
Tuesday, March 14th @ 12pm
Meeting ID: 922 8097 6769
Abstract: Plants are continuously subjected to the attack of pathogens and can survive because they have evolved specialized defense mechanisms to cope with the intruders. The investigation of the mechanisms by mean of which plants can activate the innate immunity constitutes the main objective of the research I am conducting at INSIBIO. When plants get in contact with microorganisms a multitude of molecules of different nature participate in the interactions, and depending on whether the plant recognizes, or not, a particular molecule will react letting the intruder to affect it, or mount a defense strategy to repel it. The molecules involved in the onset of a defense response are called “elicitor”. Numerous types of elicitors have been reported including proteins, peptides, glycoproteins, lipids, and oligosaccharides which were isolated from bacteria, fungi, and oomycetes. In our laboratory we have isolated and characterized a 34 kDa (286 aa) protein that was obtained from the isolate SS71 of the fungus Acremonium strictum, called AsES (as for A. strictum Elicitor Subtilisin), and exhibiting the capacity to induce the innate immunity in strawberry plants. The protein AsES proved to be successful in controlling Colletotrichum acutatum, and Botrytis cinerea, the etiological agents of the strawberry anthracnose and gray mold diseases, respectively. Strawberry plants treated with AsES exhibit the increase of many biochemical, physiological and molecular defense markers, namely: intracellular oxidative burst (e.g. H2O2 and O2.-), calcium influx, salicylic acid accumulation, ethylene production, callose and lignin deposition, and the upregulation of genes involved in the onset of the defense response (e.g. FaPR1, FaPAL1-6, FaCHI2.1, FaICS1, FaACS1-4, FaACO1-2, FaERS1-2, FaETR1-2, FaEIN2,4, FaCTR1, FaPDF1.2, FaCAT, FaCDPK7, FaCML39). However, the activation of the innate immunity mediated by AsES can be seriously jeopardized if pathogens exerting a defense suppression effect are present in the crop area. In our lab we have demonstrated that a virulent isolate of the pathogen C. acutatum (M11) suppresses the defense response activated by AsES. Further studies showed that the isolate M11 produces a small molecule (< 1 kDa) that is secreted to the medium causing the suppression of the oxidative burst, and most of the biochemical, physiological and molecular markers associated to the defense response mentioned. This outcome casts a great deal of concern on the use of bioproduct to protect plants against diseases or as growth enhancers.