Brassica pathogenesis-related PR1 genes, cloning, characterization, and relationship with resistance to blackleg fungus Leptosphaeria maculans

Abstract

Induced synthesis of pathogenesis-related (PR) proteins is one aspect of defense mechanisms in p ants. Induction of PR proteins and other defense proteins might be an important component in defending against 'Leptosphaeria maculans' in 'Brassica' ssp. In this work, two ' PR1' cDNAs, 'Ypr1.1' and 'Ypr1.2', have been cloned from 'B'. napus cv. Glacier. Similarity and phylogenetic analyses showed that the two cDNAs are similar and closely phylogenetically related, but the two PR1 proteins have different predicted pl's. ' Brassica PR1' is strongly inducible in incompatible 'Brassica-L '. 'maculans' interactions but weakly inducible in compatible interactions. Salicylic acid (SA) can also induce 'PR1' expression in 'B. napus' cv. Glacier. However, no significant induction by wounding and heat shock has been detected. In addition, no significant constitutive expression of 'PR1' has been detected in healthy cotyledons, young leaves, mature leaves, flowers, and young siliques. PR1-transgenic Westar plants grow and develop normally. However, no significant effect of overexpression of 'PR1' on resistance to blackleg disease was observed.