Continuity of Procambium and Anomalous Cambium During Formation of Successive Cambia in Celosia argentea

Elżbieta Myśkow,Mirela Tulik,Edyta M Gola

doi:10.1007/s00344-019-09948-3

Elżbieta Myśkow, Mirela Tulik + Show 1 more

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https://doi.org/10.1007/s00344-019-09948-3

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Abstract

The development of woody plants is related to the continuity of the procambium and cambium. Whether such a continuity is present in plants with successive cambia, especially in those, where the first cambium is formed outside the primary vascular bundles, has not been analyzed so far. Therefore, we studied the development of vascular meristem in Celosia argentea, in which the first and successive cambial cylinders arise outside the primary bundles and, intriguingly, in the literature are interpreted as developmentally independent structures. Our results showed that in C. argentea, the outermost procambial cells maintain their meristematic characteristics during differentiation of vascular bundles and divide periclinally, forming the zone of procambium-derived cells outside the primary bundles. This zone comprises parenchyma cells bordering the bundles, and a continuous ring of the incipient cambial cells neighboring the primary cortex. Later in the development, the ability to preserve the outermost cells in the cambium undifferentiated is repeated during the formation of successive cylinders of cambia. Together, our results clearly point to the developmental continuity of the procambium and successive cambia in C. argentea, despite their seemingly spatial distinctiveness. We postulate that the mechanism demonstrated in C. argentea is universal and orchestrates the development of successive cambia in other plant species.

Highlights

The formation of the secondary vascular tissues is a polyphyletic feature gained by different groups of plants, and related to their type of growth form, such as shrubs, trees and lianas (Rowe and Speck 2005; Lens et al 2013)
In contrast to the majority of woody plants where the procambium contributes to the typical cambium origination (Larson 1994; Spicer and Groover 2010; Růžička et al 2015), in Celosia, the cambium was interpreted as not related to the primary vasculature (Balfour 1965)
Bearing in mind that the procambium and cambium are one developmental continuum (Soh 1972; Myśkow 2010), it seems puzzling whether such a lack of the continuity is the case in Celosia argentea

Summary

Introduction

The formation of the secondary vascular tissues is a polyphyletic feature gained by different groups of plants, and related to their type of growth form, such as shrubs, trees and lianas (Rowe and Speck 2005; Lens et al 2013). The primary growth and formation of conductive tissues are achieved due to the activity of a primary vascular meristem, the procambium. In majority of plants with typical secondary growth, procambium and its derived primary tissues form discrete vascular bundles in stems. In the very middle of the bundle (between metaxylem and metaphloem), remain undifferentiated and are the founder cells for the fascicular cambium (Larson 1994; Růžička et al 2015), which ensures developmental and functional continuity of both vascular meristems

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