SummaryNatural variations in gene expression provide a mechanism for multiple phenotypes to arise in an isogenic bacterial population. In particular, a sub-group termed persisters show high tolerance to antibiotics. Previously, their formation has been attributed to cell dormancy. Here we demonstrate that bacterial persisters, under β-lactam antibiotic treatment, show less cytoplasmic drug accumulation as a result of enhanced efflux activity. Consistently, a number of multi-drug efflux genes, particularly the central component TolC, show higher expression in persisters. Time-lapse imaging and mutagenesis studies further establish a positive correlation between tolC expression and bacterial persistence. The key role of efflux systems, among multiple biological pathways involved in persister formation, indicates that persisters implement a positive defense against antibiotics prior to a passive defense via dormancy. Finally, efflux inhibitors and antibiotics together effectively attenuate persister formation, suggesting a combination strategy to target drug tolerance.

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Plants monitor seasonal cues to optimize reproductive success by tuning onset of reproduction and inflorescence architecture. TERMINAL FLOWER 1 (TFL1) and FLOWERING LOCUS T (FT) and their orthologs antagonistically regulate these life history traits, yet their mechanism of action, antagonism and targets remain poorly understood. Here, we show that TFL1 is recruited to thousands of loci by the bZIP transcription factor FD. We identify the master regulator of floral fate, LEAFY (LFY) as a target under dual opposite regulation by TFL1 and FT and uncover a pivotal role of FT in promoting flower fate via LFY upregulation. We provide evidence that the antagonism between FT and TFL1 relies on competition for chromatin-bound FD at shared target loci. Direct TFL1-FD regulated target genes identify this complex as a hub for repressing both master regulators of reproductive development and endogenous signalling pathways. Our data provide mechanistic insight into how TFL1-FD sculpt inflorescence architecture, a trait important for reproductive success, plant architecture and yield.

Parasitoid wasps are abundant and diverse hymenopteran insects that lay their eggs into the internal body (endoparasitoid) or on the external surface (ectoparasitoid) of their hosts. To make a more conducive environment for the wasps’ young, both ecto- and endoparasitoids inject venoms into the host to modulate host immunity, metabolism and development. Endoparasitoids have evolved from ectoparasitoids independently in different hymenopteran lineages. Pteromalus puparum, a pupal endoparasitoid of various butterflies, represents a relatively recent evolution of endoparasitism within pteromalids. Using a combination of transcriptomic and proteomic approaches, we have identified 70 putative venom proteins in P. puparum. Most of them show higher similarity to venom proteins from the related ectoparasitoid Nasonia vitripennis than from other more distantly related endoparasitoids. In addition, 13 venom proteins are similar to venoms of distantly related endoparasitoids but have no detectable venom matches in Nasonia. These venom proteins may have a role in adaptation to endoparasitism. Overall, these results lay the groundwork for more detailed studies of venom function and adaptation to the endoparasitic lifestyle.

In the present study, three types of coloured fibre cottons, i.e. white, brown and green, were compared for their fibre quality and yield. The comparison of fibre quality suggested that coloured fibre cotton was inferior as compared with white fibre cotton. To understand the effect of cellulose, mineral elements [nitrogen (N), phosphorus (P) and potassium (K)] and pH of fibre cells on the quality of fibre, these components were studied at different fibre cell developed stages in all three fibre cotton types. The cellulose content is closely associated with the quality of fibre. The higher fibre quality of white fibre cotton might be the result of the high cellulose content in it compared with coloured fibre cotton. A rapid and slow decrease in pH in white and coloured cottons, respectively, might have some effects on fibre elongation. Among the mineral contents, potassium is positively correlated with the fibre quality traits. The pigment development patterns in brown and green fibre cottons are not similar. In green fibre cotton it takes more time to deepen in colour as compared with brown fibre cotton. Possible strategies for the improvement in quality of coloured fibre cotton are discussed. The results of heterosis studies in coloured fibre cotton suggest that heterosis could improve yield and quality of coloured fibre cotton. In the present study, the hybrids between ZJU12A x ZJU05R and ZJU18A x ZJU01R, having an acceptable lint colour types plus better fibre quality and high yield performance, may be exploited further for their heterotic advantages.