Premium
Salicylic acid activates poplar defense against the biotrophic rust fungus Melampsora larici‐populina via increased biosynthesis of catechin and proanthocyanidins
Author(s) -
Ullah Chhana,
Tsai ChungJui,
Unsicker Sybille B.,
Xue Liangjiao,
Reichelt Michael,
Gershenzon Jonathan,
Hammerbacher Almuth
Publication year - 2019
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.15396
Subject(s) - jasmonic acid , salicylic acid , phenylpropanoid , rust (programming language) , biology , abscisic acid , plant defense against herbivory , biosynthesis , defence mechanisms , botany , jasmonate , biochemistry , gene , arabidopsis , computer science , mutant , programming language
Summary Poplar trees synthesize flavan‐3‐ols (catechin and proanthocyanidins) as a defense against foliar rust fungi, but the regulation of this defense response is poorly understood. Here, we investigated the role of hormones in regulating flavan‐3‐ol accumulation in poplar during rust infection. We profiled levels of defense hormones, signaling genes, and flavan‐3‐ol metabolites in black poplar leaves at different stages of rust infection. Hormone levels were manipulated by external sprays, genetic engineering, and drought to reveal their role in rust fungal defenses. Levels of salicylic acid ( SA ), jasmonic acid, and abscisic acid increased in rust‐infected leaves and activated downstream signaling, with SA levels correlating closely with those of flavan‐3‐ols. Pretreatment with the SA analog benzothiadiazole increased flavan‐3‐ol accumulation by activating the MYB – bHLH – WD 40 complex and reduced rust proliferation. Furthermore, transgenic poplar lines overproducing SA exhibited higher amounts of flavan‐3‐ols constitutively via the same transcriptional activation mechanism. These findings suggest a strong association among SA , flavan‐3‐ol biosynthesis, and rust resistance in poplars. Abscisic acid also promoted poplar defense against rust infection, but likely through stomatal immunity independent of flavan‐3‐ols. Jasmonic acid did not confer any apparent defense responses to the fungal pathogen. We conclude that SA activates flavan‐3‐ol biosynthesis in poplar against rust infection.