Directional transport of the phytohormone auxin is a versatile, plant-specific mechanism regulating many aspects of plant development. The recently identified plant hormones, strigolactones (SLs), are implicated in many plant traits; among others, they modify the phenotypic output of PIN-FORMED (PIN) auxin transporters for fine-tuning of growth and developmental responses. Here, we show in pea and Arabidopsis that SLs target processes dependent on the canalization of auxin flow, which involves auxin feedback on PIN subcellular distribution. D14 receptor-and MAX2 F-box-mediated SL signaling inhibits the formation of auxin-conducting channels after wounding or from artificial auxin sources, during vasculature de novo formation and regeneration. At the cellular level, SLs interfere with auxin effects on PIN polar targeting, constitutive PIN trafficking as well as clathrin-mediated endocytosis. Our results identify a non-transcriptional mechanism of SL action, uncoupling auxin feedback on PIN polarity and trafficking, thereby regulating vascular tissue formation and regeneration.

This study provides valuable information on the chemical stability of GR24 in different plant growth media and buffers. Such information is valuable for scientists using GR24 treatments to study SL-regulated processes in plants. © 2017 Society of Chemical Industry.

Strigolactones (SLs) are important plant hormones that are produced via the carotenoid biosynthetic pathway and occur at extremely low concentrations in various plant species. They regulate root development, play important roles in symbioses between higher plants and mycorrhizal fungi, and stimulate germination of plant-parasitic Orobanche and Striga species. Chemical analysis is central to research on the biochemistry of SLs and their roles in developmental biology and plant physiology. Here we summarize key issues relating to the identification and quantification of SLs isolated from plant tissues and exudates. The advantages and drawbacks of different protocols used for strigolactone analysis are discussed, and guidelines for selecting a procedure that will minimize losses during isolation and purification prior to final analysis are proposed. Hyphenated techniques suitable for SL analysis such as GC-MS and LC-MS/ MS are also discussed, and newer ambient techniques such as HR-DART-MS and DESI-MS are highlighted as tools with considerable potential in SL research. A key advantage of these methods is that they require only simply sample preparation.

In order to provide a general picture of phytochemical characteristics of nectar honey, honeydew, and mixed honeys, an overall comparison of physicochemical parameters, and phenolic profile as well as antioxidant activity of various types of honey samples has been made. Among all samples analysed, honeydew samples possess the best quality parameters in the mean content of hydroxymethylfurfural, proline, and diastase activity. Moreover, the highest content of phenolic compounds as potential radical scavengers was found in honeydews, then in mixed and multifloral nectar honeys, while samples of monofloral honeys revealed the lowest, but still considerable amounts of natural antioxidants. The overall results of this study indicate that the quality parameters as well as the distribution of phenolic acids and flavonoids are affected by the type of honey.

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