Human Peptidyl Prolyl Cis/Trans Isomerase NIMA Interacting 4 Protein ELISA kit

The plant hormone auxin and its directional transport are known to play a crucial role in defining the embryonic axis and subsequent development of the body plan. Although the role of PIN auxin efflux transporters has been clearly assigned during embryonic shoot and root specification, the role of the auxin influx carriers AUX1 and LIKE-AUX1 (LAX) proteins is not well established. Here, we used chemical and genetic tools on Brassica napus microspore-derived embryos and Arabidopsis thaliana zygotic embryos, and demonstrate that AUX1, LAX1 and LAX2 are required for both shoot and root pole formation, in concert with PIN efflux carriers. Furthermore, we uncovered a positive-feedback loop between MONOPTEROS-(ARF5)dependent auxin signalling and auxin transport. This MONOPTEROS dependent transcriptional regulation of auxin influx (AUX1, LAX1 and LAX2) and auxin efflux (PIN1 and PIN4) carriers by MONOPTEROS helps to maintain proper auxin transport to the root tip. These results indicate that auxin-dependent cell specification during embryo development requires balanced auxin transport involving both influx and efflux mechanisms, and that this transport is maintained by a positive transcriptional feedback on auxin signalling.

The present study documented the action of a potential allelochemical, narciclasine, on auxin transport in Arabidopsis by mainly affecting subcellular trafficking of PIN and AUX1 proteins and through interfering actin cytoskeletal organization. Narciclasine (NCS), an Amaryllidaceae alkaloid isolated from Narcissus tazetta bulbs, has potential allelopathic activity and affects auxin transport. However, little is known about the cellular mechanism of this inhibitory effect of NCS on auxin transport. The present study characterizes the effects of NCS at the cellular level using transgenic Arabidopsis plants harboring the promoters of PIN, in combination with PIN-GFP proteins or AUX1-YFP fusions. NCS treatment caused significant reduction in the abundance of PIN and AUX1 proteins at the plasma membrane (PM). Analysis of the subcellular distribution of PIN and AUX1 proteins in roots revealed that NCS induced the intracellular accumulation of auxin transporters, including PIN2, PIN3, PIN4, PIN7 and AUX1. However, other PM proteins, such as PIP2, BRI1, and low temperature inducible protein 6b (LTI6b), were insensitive to NCS treatment. NCS-induced PIN2 compartments were further defined using endocytic tracer FM 4-64 labeled early endosomes and suggested that this compound affects the endocytosis trafficking of PIN proteins. Furthermore, pharmacological analysis indicated that the brefeldin A (BFA)-insensitive pathway is employed in the cellular effects of NCS on PIN2 trafficking. Although NCS did not alter actin dynamics in vitro, it resulted in the depolymerization of the actin cytoskeleton in vivo. This disruption of actin filaments by NCS subsequently influences the actin-based vesicle motility. Hence, the elucidation of the specific role of NCS is useful for further understanding the mechanisms of allelopathy at the phytohormone levels.