Chemical inhibition of Arabidopsis PIN-FORMED auxin transporters by the anti-inflammatory drug naproxen

The phytohormone auxin plays central roles in many growth and developmental processes in plants.Development of chemical tools targeting the auxin pathway is useful for both plant biology and agriculture.Here we reveal that naproxen,a synthetic compound with anti-inflammatory activity in humans,acts as an auxin transport inhibitor targeting PIN-FORMED(PIN)transporters in plants.Physiological experiments indicate that exogenous naproxen treatment affects pleiotropic auxin-regulated developmental processes.Additional cellular and biochemical evidence indicates that naproxen suppresses auxin transport,specifically PIN-mediated auxin efflux.Moreover,biochemical and structural analyses confirm that naproxen binds directly to PIN1 protein via the same binding cavity as the indole-3-acetic acid substrate.Thus,by combining cellular,biochemical,and structural approaches,this study clearly establishes that naproxen is a PIN inhibitor and elucidates the underlying mechanisms.Further use of this compound may advance our understanding of the molecular mechanisms of PIN-mediated auxin transport and expand our toolkit in auxin biology and agriculture.

Gapless indica rice genome reveals synergistic contributions of active transposable elements and segmental duplications to rice genome evolution

The ultimate goal of genome assembly is a high-accuracy gapless genome.Here,we report a new assembly pipeline that is used to produce a gapless genome for the indica rice cultivar Minghui 63.The resulting 397.71-Mb final assembly is composed of 12 contigs with a contig N50 size of 31.93 Mb.Each chromosome is represented by a single contig and the genomic sequences of all chromosomes are gapless.Quality evaluation of this gapless genome assembly showed that gene regions in our assembly have the highest completeness compared with the other 15 reported high-quality rice genomes.Further comparison with the japonica rice genome revealed that the gapless indica genome assembly contains more transposable elements(TEs)and segmental duplications(SDs),the latter of which produce many duplicated genes that can affect agronomic traits through dose effect or sub-/neo-functionalization.The insertion of TEs can also affect the expression of duplicated genes,which may drive the evolution of these genes.Furthermore,we found the expansion of nucleotide-binding site with leucine-rich repeat disease-resistance genes and cis-zeatin-O-glucosyltransferase growth-related genes in SDs in the gapless indica genome assembly,suggesting that SDs contribute to the adaptive evolution of rice disease resistance and developmental processes.Collectively,our findings suggest that active TEs and SDs synergistically contribute to rice genome evolution.

Molecular mechanisms of N‑1‑naphthylphthalamic acid,a chemical tool in plant biology and agriculture

The phytohormone auxin plays essential roles in modulating plant growth and development by regulating cell expansion,division,and differentiation.Genetic or pharmacological interference of the auxin pathway affects multiple growth and patterning processes in plants(Vanneste and Friml 2009).The research on auxin can be tracked to the earliest observations on plant growth regulation and phototropism by Sachs and Darwin in the nineteenth century(Friml 2022).Indole-3-acetic acid(IAA)is the major natural auxin form,and decades of genetic and biochemical studies have established the molecular framework for auxin biosynthesis,signaling,and transport(Friml 2022).