The glaucous appearance of wheat and barley plants, that is the light bluish-grey look of flag leaf, stem, and spike surfaces, results from deposition of cuticular β-diketone wax on their surfaces; this phenotype is associated with high yield, especially under drought conditions. Despite extensive genetic and biochemical characterization, the molecular genetic basis underlying the biosynthesis of β-diketones remains unclear. Here we discovered that the wheat W1 locus contains a metabolic gene cluster mediating β-diketone biosynthesis. The cluster comprises genes encoding proteins of several families including type-III polyketide synthases, hydrolases, and cytochrome P450s related to known fatty acid hydroxylases. The cluster region was identified in both genetic and physical maps of glaucous and glossy tetraploid wheat, demonstrating entirely different haplotypes in these accessions. Complementary evidence obtained through gene silencing in planta and heterologous expression in bacteria supports a model for a β-diketone biosynthesis pathway involving members of these three protein families. Mutations in homologous genes were identified in the barley eceriferum mutants defective in β-diketone biosynthesis, demonstrating a gene cluster also in the β-diketone biosynthesis Cer-cqu locus in barley. Hence, our findings open new opportunities to breed major cereal crops for surface features that impact yield and stress response.

Salmonella profits from immunometabolism: Extensive metabolic rewiring occurs in various immune cells during the course of infection. Whether these changes can be exploited by intracellular pathogens remains an open question. Rosenberg et al. report that infection with Salmonella enterica serovar Typhimurium ( S. Tm) induces the accumulation of the metabolite succinate in macrophages (see the Perspective by Lynch and Lesser). This key intermediate in the citric acid cycle activates virulence genes in S. Tm, leading to microbial resistance. Moreover, the active transport of succinate through the C4-dicarboxylate transporter DcuB is required for S. Tm virulence and survival within macrophages. Sensing of citric acid cycle intermediates may more generally serve as a cue to initiate the resistance programs of intracellular pathogens. Science , this issue p. 400 ; see also p. 344

Microbial communities employ a variety of complex strategies to compete successfully against competitors sharing their niche, with antibiotic production being a common strategy of aggression. Here, by systematic evaluation of four non-ribosomal peptides/polyketide (NRPs/PKS) antibiotics produced by Bacillus subtilis clade, we revealed that they acted synergistically to effectively eliminate phylogenetically distinct competitors. The production of these antibiotics came with a fitness cost manifested in growth inhibition, rendering their synthesis uneconomical when growing in proximity to a phylogenetically close species, carrying resistance against the same antibiotics. To resolve this conflict and ease the fitness cost, antibiotic production was only induced by the presence of a peptidoglycan cue from a sensitive competitor, a response mediated by the global regulator of cellular competence, ComA. These results experimentally demonstrate a general ecological concept – closely related communities are favoured during competition, due to compatibility in attack and defence mechanisms.

Significance: Studies in mice and humans have revealed daytime variance in exercise performance, yet it is still unclear whether and how these daytime differences are regulated by the circadian clock. Here, we show that exercise performance is circadian clock controlled and that specific clock proteins modify exercise capacity in a time-dependent manner, likely through differences in food consumption and liver glycogen stores. We also demonstrate that the time of day at which training is performed plays a role in improving exercise capacity. Our study suggests that exercise capacity is shaped by clock proteins and training in a daytime-dependent manner.