Auxin: a master regulator in plant root development

Abstract

The demand for increased crop productivity and the predicted challenges related to plant survival under adverse environmental conditions have renewed the interest in research in root biology. Various physiological and genetic studies have provided ample evidence in support of the role of plant growth regulators in root development. The biosynthesis and transport of auxin and its signaling play a crucial role in controlling root growth and development. The univocal role of auxin in root development has established it as a master regulator. Other plant hormones, such as cytokinins, brassinosteroids, ethylene, abscisic acid, gibberellins, jasmonic acid, polyamines and strigolactones interact either synergistically or antagonistically with auxin to trigger cascades of events leading to root morphogenesis and development. In recent years, the availability of biological resources, development of modern tools and experimental approaches have led to the advancement of knowledge in root development. Research in the areas of hormone signal perception, understanding network of events involved in hormone action and the transport of plant hormones has added a new dimension to root biology. The present review highlights some of the important conceptual developments in the interplay of auxin and other plant hormones and associated downstream events affecting root development.

Is the auxin influx carrierLAX3essential for plant growth and development in the model plantsMedicago truncatula, Lotus japonicusandArabidopsis thaliana?

“…It is known that the combined action of auxin efflux carriers PIN1, PIN4 and PIN7 plays an essential role in auxin transport, cell division and auxin distribution during all stages of zygotic embryogenesis. [36,61,64,65] Since it is well known that auxin cell-to-cell transport is mediated by auxin influx (LAX proteins) and efflux (PIN proteins) carriers [40] and the plant hormone auxin plays an important role in every aspect of plant growth and development, including embryogenesis, [1,66] we confirmed the involvement of MtLAX3 in somatic embryo development.…”

“…[29,37,38] The first putative efflux carrier to be characterized was AtPIN1. [39,40] AtPIN is a family of polar auxin efflux transporters localized in the plasma membrane with a central role in many plant processes. [32,41] PGPs are involved in both influx and efflux, [42] but with a minor role.…”

Enraizamiento in vitro y ex vitro de microtallos de Ugni molinae Turcz., una especie nativa de Chile

“…El AIB es más estable y efectivo que AIA para la inducción de raíces laterales, además puede ser convertido a AIA en los peroxisomas por β-oxidación (Zolman et al 2000, Woodward & Bartel 2005. Según Pop et al (2011), el AIB puede potenciarse con los contenidos de AIA endógeno, en este caso puede ser explicada por una mayor estabilidad, diferentes metabolismos, diferencia en el transporte y la conversión del AIB en AIA, esta interacción AIB-AIA difiere entre las especies, lo que también puede reflejarse entre clones distintos de una misma especie (Ludwig-Müller et al 2005, Saini et al 2013.…”

“…Otro aspecto importante son los reguladores de crecimiento utilizados en la etapa anterior (multiplicación de los microtallos); las citoquininas y giberelinas utilizadas ampliamente en el desarrollo de brotes axilares, se han descrito también como inhibidores del enraizamiento (Pop et al 2011, Saini et al 2013. Por otra parte, niveles altos de bencilaminopurina (BAP) se manifiestan a menudo en brotes hiperhídricos con problemas en la fase de aclimatación (Rodríguez 2011).…”

In vitro regeneration, Agrobacterium-mediated transformation, and genetic assay of chalcone synthase in the medicinal plant Echinacea pallida

“…1) and more than 90% of the plantlets propagated through tissue culture survived acclimation. Auxins induce plant rooting and regulate root growth (Overvoorde et al 2010;Saini et al 2013;Perianez-Rodriguez et al 2014;Chandler and Werr 2015), but auxin is not necessary for root organogenesis in in vitro regeneration of Echinacea species (Harbage 2001). In addition, even a very low concentration of auxins inhibits Echinacea root induction.…”