Salicylic acid receptors activate jasmonic acid signalling through a non-canonical pathway to promote effector-triggered immunity.

It is an apparent conundrum how plants evolved effector-triggered immunity (ETI), involving programmed cell death (PCD), as a major defence mechanism against biotrophic pathogens, because ETI-associated PCD could leave them vulnerable to necrotrophic pathogens that thrive on dead host cells. Interestingly, during ETI, the normally antagonistic defence hormones, salicylic acid (SA) and jasmonic acid (JA) associated with defence against biotrophs and necrotrophs respectively, both accumulate to high levels. In this study, we made the surprising finding that JA is a positive regulator of RPS2-mediated ETI. Early induction of JA-responsive genes and de novo JA synthesis following SA accumulation is activated through the SA receptors NPR3 and NPR4, instead of the JA receptor COI1. We provide evidence that NPR3 and NPR4 may mediate this effect by promoting degradation of the JA transcriptional repressor JAZs. This unique interplay between SA and JA offers a possible explanation of how plants can mount defence against a biotrophic pathogen without becoming vulnerable to necrotrophic pathogens

Ethyl 7-(4-bromo­phen­yl)-5-trifluoro­methyl-4,7-dihydro­tetra­zolo[1,5-a]pyrimidine-6-carboxyl­ate

In the title compound, C14H11BrF3N5O2, the pyrimidine ring adopts a flattened envelope conformation with sp 3-hybridized carbon as the flap [deviation = 0.177 (3) Å]. The dihedral angle between tetra­zole and bromo­phenyl rings is 84.3 (1)°. In the crystal, mol­ecules are linked into centrosymmetric dimers by pairs of N—H⋯N hydrogen bonds

{2,2′-[1,1′-(Ethyl­enedioxy­dinitrilo)diethyl­idyne]di-1-naphtholato}copper(II)

The title complex, [Cu(C26H22N2O4)], is isostructural with its Ni analogue. All intramolecular distances and angles are very similar for the two structures, whereas the packing of the molecules, including C—H⋯O and C—H⋯π interactions, are slightly different

5′-Amino-2-oxo-2′,3′-dihydro­spiro­[indoline-3,7′-thieno[3,2-b]pyran]-6′-carbonitrile 1′,1′-dioxide

In the title compound, C15H11N3O4S, the dihedral angle between the mean planes of the dihydro­indol-2-one (r.m.s. deviation = 0.015 Å) and dihydro­thieno[3,2-b]pyran (r.m.s. deviation = 0.011 Å) ring systems is 89.53 (3)°. The crytal packing is consolidated by inter­molecular N—H⋯O and N—H⋯N hydrogen bonds, which link the mol­ecules into a two-dimensional network into sheets lying parallel to (100)

2,2′-[1,1′-(Octane-1,8-diyldioxy­dinitrilo)diethyl­idyne]diphenol

The title compound, C24H32N2O4, has a crystallographic inversion centre at the mid-point of the central C—C bond. At each end of the mol­ecule, intra­molecular O—H⋯N hydrogen bonds generate six-membered S(6) ring motifs. The crystal structure is stabilized by pairs of weak inter­molecular C—H⋯O hydrogen bonds that link neighbouring mol­ecules into R 2 2(40) ring motifs, which in turn form infinite one-dimensional supra­molecular ribbon structures

4-({4-[1-(Methoxy­imino)eth­yl]anilino}(phen­yl)methyl­ene)-3-methyl-2-phenyl-1H-pyrazol-5(4H)-one

In the title compound, C26H24N4O2, the dihedral angles between the central pyrazole ring and the other three benzene rings are 40.02 (3), 77.51 (5) and 55.72 (3)°. A strong intra­molecular N—H⋯O hydrogen bond forms a six-membered ring with an S(6) motif. In the crystal structure, a weak inter­molecular C—H⋯N inter­action with graph-set motif R 2 2(8) and C—H⋯O hydrogen bonds link each mol­ecule to three others, forming an infinite two-dimensional supra­molecular structure

A cytoplasmic Cu-Zn superoxide dismutase SOD1 contributes to hyphal growth and virulence of Fusarium graminearum

AbstractSuperoxide dismutases (SODs) are scavengers of superoxide radicals, one of the main reactive oxygen species (ROS) in the cell. SOD-based ROS scavenging system constitutes the frontline defense against intra- and extracellular ROS, but the roles of SODs in the important cereal pathogen Fusarium graminearum are not very clear. There are five SOD genes in F. graminearum genome, encoding cytoplasmic Cu-Zn SOD1 and MnSOD3, mitochondrial MnSOD2 and FeSOD4, and extracellular CuSOD5. Previous studies reported that the expression of SOD1 increased during infection of wheat coleoptiles and florets. In this work we showed that the recombinant SOD1 protein had the superoxide dismutase activity in vitro, and that the SOD1-mRFP fusion protein localized in the cytoplasm of F. graminearum. The Δsod1 mutants had slightly reduced hyphal growth and markedly increased sensitivity to the intracellular ROS generator menadione. The conidial germination under extracellular oxidative stress was significantly delayed in the mutants. Wheat floret infection assay showed that the Δsod1 mutants had a reduced pathogenicity. Furthermore, the Δsod1 mutants had a significant reduction in production of deoxynivalenol mycotoxin. Our results indicate that the cytoplasmic Cu-Zn SOD1 affects fungal growth probably depending on detoxification of intracellular superoxide radicals, and that SOD1-mediated deoxynivalenol production contributes to the virulence of F. graminearum in wheat head infection