Vascular Cambium Development

Abstract

Secondary phloem and xylem tissues are produced through the activity of vascular cambium, the cylindrical secondary meristem which arises among the primary plant tissues. Most dicotyledonous species undergo secondary development, among them Arabidopsis. Despite its small size and herbaceous nature, Arabidopsis displays prominent secondary growth in several organs, including the root, hypocotyl and shoot. Together with the vast genetic resources and molecular research methods available for it, this has made Arabidopsis a versatile and accessible model organism for studying cambial development and wood formation. In this review, we discuss and compare the development and function of the vascular cambium in the Arabidopsis root, hypocotyl, and shoot. We describe the current understanding of the molecular regulation of vascular cambium and compare it to the function of primary meristems. We conclude with a look at the future prospects of cambium research, including opportunities provided by phenotyping and modelling approaches, complemented by studies of natural variation and comparative genetic studies in perennial and woody plant species.

Type-B ARABIDOPSIS RESPONSE REGULATORs Specify the Shoot Stem Cell Niche by Dual Regulation of WUSCHEL

“…Evidence accumulated in the past few years suggests that the distinct distribution of these two hormones plays pivotal roles in tissue patterning (Chandler and Werr, 2015;Schaller et al, 2015). For instance, in the vascular tissue of Arabidopsis roots, a central localized xylem axis bisects the intervening procambium cells and thus forms a bisymmetric structure (Nieminen et al, 2015;De Rybel et al, 2016). Cytokinin signaling peaks in two bisymmetric procambial cell files, where it regulates the localization of PINFORMED (PIN) auxin efflux carriers and creates an auxin maximum in the adjacent xylem axis.…”

The role of cytokinins in clubroot disease

“…Recently Schuller et al (2014) found that brassinosteroid (BR) biosynthesis was up-regulated in enlarged cells and that mutations in the BR receptor (bri1-6) and treatment with BR biosynthesis inhibitors reduced gall formation. Given the importance BR and other hormones such as strigolactones in regulating cambial activity and their extensive interactions with auxin and cytokinin (Nieminen et al 2015) a detailed microscopic analysis of host and plasmodial development in plants with mutations in these signalling pathways is likely to be informative.…”

In-depth analysis of jasmonate-mediated indole-3-acetic acid (IAA) biosynthesis and its implication in plant development

“…Arabidopsis secondary growth has been observed to occur in root, hypocotyl and stem (Nieminen et al 2015). Moreover, a comparative analysis between Arabidopsis and poplar hypocotyls has demonstrated that the produced secondary xylem of both plant species exhibit striking similarities in terms of tissue organization, albeit…”

“…After subsequent periclinal divisions (parallel to the axis/surface) of the procambium during the late globular stage, heart stage and torpedo stage, the mature embryo displays a radial vascular patter with the vascular tissue in the center (Miyashima et al 2013). These embryonic-derived provascular tissues will generate the vascular system in the primary root and hypocotyl, whereas the shoot apical tissue is derived from the SAM (Nieminen et al 2015). On the other hand, in the embryonic cotyledons only a procambial tissue is extended in an apical-basal axis and will generate the leave veins (De Rybel et al 2015).…”

“…Final growth and In addition to the development, growth and maintenance of the primary vascular tissues, Arabidopsis and some other plant species undergo secondary growth to enlarge the girth of the plant organs (Barra-Jiménez and Ragni, 2017). During this event, a secondary lateral meristem called vascular cambium, originates from the procambium, starts to divide periclinally to give rise to the secondary xylem (inwards) and the secondary phloem (outwards) (Schuetz et al 2013;Nieminen et al 2015;De Rybel et al 2015). Cell wall composition is influenced by diverse developmental and environmental stimuli.…”