Role of pectin methylesterases and their inhibitors during Eucalyptus grandis infection by Puccinia psidii, eucalyptus rust causaul agent

Abstract

The objective of the present project is the analyzing of the pectin methylesterases (PMEs) expression by Puccinia psidii Winter, causal agent of eucalyptus rust, during the infection process of Eucalyptus grandis. In contrast, the host response will also be investigated by analyzing the expression of the pectin methyl esteraseinhibitors (PMEI). Plants of E. grandis clone S4, susceptible to the pathogen, and R3, resistant to the pathogen will be inoculated with spores of the P. psidii , isolate MF-1.. The sampling will be conducted at different times: zero hours after inoculation (h.a.i) (control), 6 h.a.i (appressorium formation), 12 h.a.i (pathogen penetration), 24 h.a.i (haustorium formation), 72 h.a.i (formation of secondary hyphae) and 144 h.a.i (sporulation fungus) during the infection process for obtaining mRNA from the plant and fungus. Specific primers to the genes of pectin methylesterases of the fungus and pectin methyl esterase inhibitors of the planta will be designed and the analysis of expression of these genes is performed by RT-qPCR. Pectinases, in particular PME, are essential for understanding the mechanism of pathogenicity, since they are the primary enzymes that act in the degradation of cell wall polymer found in the cell, allowing the colonization of the host. The plants, in response to defense, express PME inhibitors. Despite the importance of these enzymes, little is known about this system during the E.grandis-P.psidii interaction. Thus, the study of pectinase PMEs expressed by the fungus to infect the plant and expression of inhibitors PMEI synthesized by plants as a defense will collaborate with the better understanding of the mechanisms related to pathogenicity and host response for the development of new control strategies.