L-PROLINE CATABOLISM ALONG DEVELOPMENT OF THEHYPERSENSITIVERESPONSE

CECCHINI NM; MARIELA INES MONTEOLIVA; NOTA MF; BLANCO F; HOLUIGUE L; ÁLVAREZ ME

Congreso; - SAIB - 43 Annual Meeting XLIII Reunión Anual rd Argentine Society for Biochemistry and Molecular Biology Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2007

Although plants accumulate L-proline (Pro) in response to severalabiotic stresses, external Pro supply results toxic and this toxicity isapparently mediated by accumulation of reactive oxygen species(ROS). Pro catabolism takes place in mitochondria involving twoconsecutive steps catalyzed by ProDH and P5CDH. We haveobserved that Pro catabolism is altered intissues developing the Hypersensitive Response (HR) triggered byavirulent races of . Induction of andrepression of occur in these tissues. We here evaluated ifand genes are regulated by SA/JA/ROS andanalyzed the requirement of ProDH for HR development.We foundthat , a salt- and ROS-sensitive gene which down regulatestrough a natural siRNA, was activated inHR. SA and JA stimulate similar , andtranscriptional changes than those induced by the avirulentpathogen. To analyze if ProDH affects ROS generation,siRNA lines were constructed. ROS induced by the avirulentpathogen or by external Pro treatment were diminished in thesetransgenic plants. Our results suggest that ProDH-mediated Prodegradation may affect HR development by modulating ROSgeneration.