Role of Salicylic Acid and Components of the Phenylpropanoid Pathway in Basal and Cultivar-Related Resistance of Oilseed Rape (Brassica napus) to Verticillium longisporum
Zheng, Xiaorong ; Koopmann, Birger ; von Tiedemann, Andreas
Citable Link (URL):http://resolver.sub.uni-goettingen.de/purl?gs-1/16657
Journal Article (Published version)
First published (peer reviewed)
Plants 2019; 8(11): Art. 491
Abstract
Enhanced resistance is a key strategy of controlling ‘Verticillium stem striping’ in Brassica
napus caused by the soil-borne vascular pathogen Verticillium longisporum. The present study analyses
the role of a broad range of components in the phenylpropanoid and salicylic acid (SA) pathways
in basal and cultivar-related resistance of B. napus towards V. longisporum. A remarkable increase
of susceptibility to V. longisporum in SA-deficient transgenic NahG plants indicated an essential role
of SA in basal resistance of B. napus to V. longisporum. Accordingly, elevated SA levels were also
found in a resistant and not in a susceptible cultivar during early asymptomatic stages of infection
(7 dpi), which was associated with increased expression of PR1 and PR2. In later symptomatic
stages (14 or 21 dpi), SA responses did not di er anymore between cultivars varying in resistance.
In parallel, starting at 7 dpi, an overall increase in phenylpropanoid syntheses developed in the
resistant cultivar, including the activity of some key enzymes, phenylalanine ammonium lyase (PAL),
cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POX) and the expression of key genes,
PAL4, CCoAMT, CCR, POX. As a consequence, a remarkable increase in the levels of phenolic acids
(t-cinnamic acid, p-coumaric acid, ca eic acid, ferulic acid, sinapic acid) occurred associated with
cultivar resistance. A principal component analysis including all 27 traits studied indicated that
component 1 related to SA synthesis (PR1, PR2, POX, level of free SA) and component 2 related to
lignin synthesis (level of free ferulic acid, free p-coumaric acid, conjugated t-cinnamic acid) were the
strongest factors to determine cultivar-related resistance. This study provides evidence that both SA
and phenolic acid synthesis are important in cultivar-related resistance, however, with di erential
roles during asymptomatic and symptomatic stages of infection.
Sponsor:
Open-Access-Publikationsfonds 2019