A critical analysis of phosphatidic acid mediated resistance response in Sinapis alba against Alternaria brassicicola.

The enhanced expression of PLD genes and the quantitative increase in the level of phosphatidic acid (PA) in resistant Sinapis alba compared to the downregulated or unchanged expression of the PLD genes and decreased PA level in susceptible Brassica juncea when challenged with Alternaria brassicicola , indicated a positive relationship between PA-mediated signalling and resistance against this necrotrophic pathogen. Furthermore, spraying PA onto the susceptible species B. juncea increased resistance and enhanced expression of ABA-responsive genes, which was comparable to the expression of these genes in S. alba when challenged with A. brassicicola . • The enhanced expression of several PLD genes in resistant S. alba was observed compared to B. juncea upon challenge with A. brassicicola . • An increase in the PA level in S. alba compared to B. juncea following interaction with the pathogen. • Leaves of B. juncea incubated on PA-soaked filter paper did not show resistance. • Spraying B. juncea leaves with PA led to resistance as well as to the enhanced expression of ABA-responsive genes. • A temporal increase in the PA level is associated with increased resistance against A. brassicicola . [ABSTRACT FROM AUTHOR]