PHYSIOLOGICAL AND TRANSCRIPTOMIC CHANGES IN Brassica napus COTYLEDONS TREATED WITH SIRODESMIN PL PHYTOTOXIN

ELLIOTT, CANDACE; ROMERO FERNANDO MATÍAS; IDNURM, ALEXANDER; MAIALE, SANTIAGO JAVIER; GARRIZ, ANDRES; ROSSI FRANCO RUBÉN; POMBO. MARINA; ROSLI, HERNAN; RUIZ, OSCAR

Congreso; XXXIII Argentinian meeting of Plant Physiology; 2021

Brassicanapus (colza,canola) is the second-largest oilseed crop produced worldwide.  Hemibiotrophic fungus Leptosphaeria maculans, is a devastating pathogen that causesblackleg disease in this plant species. Yield reduction and importanteconomical losses are associated to infected plants because of a restriction inwater and nutrient transport through the stem. It has been demonstrated thatSirodesmin PL is the major component of phytotoxic extracts produced by L. maculans and mutantisolates, unable to produce Sirodesmin PL, are less virulent on stems of B. napus.Nevertheless, the toxicity-mediating mechanisms are yet far from beingunderstood. Here, we present results from global transcriptomic andphysiological studies after treatment of B. napus cotyledons with Sirodesmin PL. GeneOntology term enrichment of differentially expressed genes (DEGs) indicatedthat this toxin induced genes associated to different plant defense responsessuch as those involved in hormonal pathways, ROS accumulation and callosedeposition. We also found that Sirodesmin PL suppressed genes associated tophotosynthesis. In agreement with this, we corroborated that the wholephotosynthetic activity was negatively affected by the treatment. Parametersassociated with chlorophyll fluorescence and number of chloroplasts per cellwere significantly lower in the spongy and palisade parenchyma of leavestreated with Sirodesmin PL. This study makes a significant contribution to understandingthe molecular responses of B. napus toSirodesmin PL, which could promote the development of effective strategiesin L. maculans-resistancebreeding programs.