The Induction of Vascular Tissues by Auxin

Aloni, Roni

doi:10.1007/978-1-4020-2686-7_22

Cited by 72 publications

(32 citation statements)

References 84 publications

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“…Endress 1994). According to Aloni (2004), auxin plays a leading role in procambial initiation and polar auxin transport from primordia is a controlling factor in both phyllotactic (Reinhardt et al 2003) and leaf venation patterning (Scarpella & Meijer 2004, Scarpella et al 2006, resulting in self-regulated development of vascular bundles where needed. Before these modern insights were generally accepted, vascularisation development in angiosperm flowers had been assumed to be acropetal (e.g.…”

Section: Pistil Vascularisation In Cyperoideaementioning

confidence: 99%

Gynoecial anatomy and development in Cyperoideae (Cyperaceae, Poales): congenital fusion of carpels facilitates evolutionary modifications in pistil structure

Reynders¹,

Vrijdaghs²,

Larridon³

et al. 2012

Plecevo

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Background and aims -In Cyperaceae, the single-ovuled, usually triangular gynoecia are widely considered to have a basic number of three carpels, often reduced to two, resulting in dimerous pistils. However, laterally flattened dimerous pistils cannot be explained by any existing carpel reduction theories, because a single stigma in median position replaces the two adaxial stigmata. This paper presents a comparative study of the ontogenetic and anatomical adaptations facilitating the origin of new pistil forms in Cyperoideae, focusing on modified gynoecia. It includes a re-evaluation of Blaser's (1941) anatomical studies in Cyperaceae. We aim to test Blaser's hypothesis that is based on an acropetal developmental model of the floral vasculature and the general Cyperoid ontogenetic model of Vrijdaghs et al. (2009), which states that cyperoid ovaries originate from an annular primordium. Methods -SEM, dark field and phase contrast microscopy. Key Results -All cyperoid pistils studied develop according to a cyperoid floral ontogenetic pattern, in which carpel primordia are congenitally fused. In Pycreus sanguinolentus (and other species), separate procambial initiation zones were observed in both the flower receptacle and separate floral primordia, which connect (or not) at later developmental stages. Conclusions -The presence of an annular ovary primordium instead of individual carpel primordia, combined with the bidirectional development of the pistil vasculature liberate the developing gynoecium from the structural constraints proper to a typical carpellate organisation. Procambial initiation zones in the receptacular vascular plexus and in individual floral primordia constitute the basis for the formation of a flexible vascular system in cyperoid flowers. Moreover the development of the ovary and ovule are decoupled. Consequently, in Cyperoideae the acquired developmental freedom of the pistil resulted in various adaptations. Genus Model (fig. 3) Bolboschoenus (Asch.) Palla (as Scirpus L.) A1/B1 Carex L. A2/B2 Cyperus L. A2 Dulichium Pers. C1 Eleocharis R.Br. (as Heleocharis T.Lestib.) A2/C2 Eriophorum L. A1 Fimbristylis Vahl A2/B2 Lipocarpha R.Br. A2/B2 Pycreus P. Beauv. (as Cyperus L.) D1 Rhynchospora Vahl B1/B2/C1/C2 Schoenoplectus (Rchb.) Palla (as Scirpus L.) A1/B1

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Section: Pistil Vascularisation In Cyperoideaementioning

confidence: 99%

Gynoecial anatomy and development in Cyperoideae (Cyperaceae, Poales): congenital fusion of carpels facilitates evolutionary modifications in pistil structure

Reynders¹,

Vrijdaghs²,

Larridon³

et al. 2012

Plecevo

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“…Here auxin maxima and TC formation co-occur in developing minor vein networks of collection phloem (Gunning et al, 1968; Aloni et al, 2003). In the case of transport phloem, the relationship between auxin maxima and TC formation tends to be localized to stem nodes (Gunning et al, 1970; Aloni, 2010) and to sites of lateral root formation (Aloni, 2010). In developing leaves of Pisum sativum , CC/TCs differentiate concurrently with the minor vein network (Gunning et al, 1970) with development of the latter regulated by a canalized flow of auxin emanating from trichomes and mesophyll cells (Aloni et al, 2003).…”

Section: Does An Auxin-ethylene-ros Signaling Cascade Regulate Phloemmentioning

confidence: 99%

Intersection of transfer cells with phloem biology—broad evolutionary trends, function, and induction

Andriunas¹,

Zhang²,

Xia³

et al. 2013

Front. Plant Sci.

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Transfer cells (TCs) are ubiquitous throughout the plant kingdom. Their unique ingrowth wall labyrinths, supporting a plasma membrane enriched in transporter proteins, provides these cells with an enhanced membrane transport capacity for resources. In certain plant species, TCs have been shown to function to facilitate phloem loading and/or unloading at cellular sites of intense resource exchange between symplasmic/apoplasmic compartments. Within the phloem, the key cellular locations of TCs are leaf minor veins of collection phloem and stem nodes of transport phloem. In these locations, companion and phloem parenchyma cells trans-differentiate to a TC morphology consistent with facilitating loading and re-distribution of resources, respectively. At a species level, occurrence of TCs is significantly higher in transport than in collection phloem. TCs are absent from release phloem, but occur within post-sieve element unloading pathways and particularly at interfaces between generations of developing Angiosperm seeds. Experimental accessibility of seed TCs has provided opportunities to investigate their inductive signaling, regulation of ingrowth wall formation and membrane transport function. This review uses this information base to explore current knowledge of phloem transport function and inductive signaling for phloem-associated TCs. The functional role of collection phloem and seed TCs is supported by definitive evidence, but no such information is available for stem node TCs that present an almost intractable experimental challenge. There is an emerging understanding of inductive signals and signaling pathways responsible for initiating trans-differentiation to a TC morphology in developing seeds. However, scant information is available to comment on a potential role for inductive signals (auxin, ethylene and reactive oxygen species) that induce seed TCs, in regulating induction of phloem-associated TCs. Biotic phloem invaders have been used as a model to speculate on involvement of these signals.

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“…Based on observations in root apices (see Section Axial Hydraulic Conductances of Sieve Tubes are Considerably Higher than Those of Phloem Unloading Pathways), the primary site at which hormonal control is likely to be exerted over bulk flow rates is on the combined hydraulic conductances of plasmodesmata and differentiating sieve pores located in the provascular strands canalizing an axial flow of resources toward the root meristem (and see Figure 2). In addition, hormonal regulation of protophloem formation from provascular strands (Aloni, 2010) is accompanied by coalescing pit fields of plasmodesmata into sieve pores with radii several orders larger than those of plasmodesmal microchannels thus conferring substantial increases in hydraulic conductances of axial transport pathways (see Equation 2).…”

Section: How Is Sink Demand Communicated To Regulate Plasmodesmal Conmentioning

confidence: 99%

Does Don Fisher's high-pressure manifold model account for phloem transport and resource partitioning?

Patrick¹

2013

Front. Plant Sci.

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The pressure flow model of phloem transport envisaged by Münch (1930) has gained wide acceptance. Recently, however, the model has been questioned on structural and physiological grounds. For instance, sub-structures of sieve elements may reduce their hydraulic conductances to levels that impede flow rates of phloem sap and observed magnitudes of pressure gradients to drive flow along sieve tubes could be inadequate in tall trees. A variant of the Münch pressure flow model, the high-pressure manifold model of phloem transport introduced by Donald Fisher may serve to reconcile at least some of these questions. To this end, key predicted features of the high-pressure manifold model of phloem transport are evaluated against current knowledge of the physiology of phloem transport. These features include: (1) An absence of significant gradients in axial hydrostatic pressure in sieve elements from collection to release phloem accompanied by transport properties of sieve elements that underpin this outcome; (2) Symplasmic pathways of phloem unloading into sink organs impose a major constraint over bulk flow rates of resources translocated through the source-path-sink system; (3) Hydraulic conductances of plasmodesmata, linking sieve elements with surrounding phloem parenchyma cells, are sufficient to support and also regulate bulk flow rates exiting from sieve elements of release phloem. The review identifies strong circumstantial evidence that resource transport through the source-path-sink system is consistent with the high-pressure manifold model of phloem transport. The analysis then moves to exploring mechanisms that may link demand for resources, by cells of meristematic and expansion/storage sinks, with plasmodesmal conductances of release phloem. The review concludes with a brief discussion of how these mechanisms may offer novel opportunities to enhance crop biomass yields.

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The Induction of Vascular Tissues by Auxin

Cited by 72 publications

References 84 publications

Gynoecial anatomy and development in Cyperoideae (Cyperaceae, Poales): congenital fusion of carpels facilitates evolutionary modifications in pistil structure

Gynoecial anatomy and development in Cyperoideae (Cyperaceae, Poales): congenital fusion of carpels facilitates evolutionary modifications in pistil structure

Intersection of transfer cells with phloem biology—broad evolutionary trends, function, and induction

Does Don Fisher's high-pressure manifold model account for phloem transport and resource partitioning?

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