Cytoskeleton in the Parasitic Plant Cuscuta During Germination and Prehaustorium Formation.

Peter Kaštier,Michaela Martinčová,Yuliya A Krasylenko,Alžbeta Blehová,Emmanuel Panteris,Jozef Šamaj

doi:10.3389/fpls.2018.00794

Abstract

Although cytoskeleton is a driving force for cell division and growth in higher plants, there is little evidence about its components in parasitic angiosperms. Microtubules and actin filaments in cells of shoot apical meristem and root-like structure of stem holoparasites European (C. europaea L.) and Eastern (C. monogyna Vahl.) dodders, as well as in prehaustorium, the specific organ adapted to parasitism, were visualized for the first time by immunolabeling and fluorescence microscopy. The significance of cytoskeletal elements during germination and prehaustorium formation was addressed by treatments with taxol, oryzalin, latrunculin B, cytochalasin B/D, jasplakinolide, and 2,3-butanedione monoxime. In shoot apical meristem many dividing cells were observed, in contrast to root-like structure, devoid of cell divisions. Cortical microtubules were oriented transversely and/or obliquely, while actin filaments were randomly distributed in cells of both organs. Furthermore, longitudinal cortical microtubules were present in digitate cells of prehaustorium, and transverse arrays were found in its file cells. Long and short random actin filaments were also observed in prehaustorium cells. Thus, it was shown that the cytoskeleton in dodder shoot cells is organized in a similar way to non-parasitic dicots, while cytoskeletal organization has some peculiarities in quickly senescing root-like structure and prehaustorium.

Highlights

Parasitic plants are widespread weeds, agronomically and economically important in terms of harvest devastation
The fast growth of dodder seedlings is maintained by abundant microtubules (Figure 1D) in shoot apical meristem cells and their high meristematic activity by the rearrangement between cortical and mitotic arrays (Figure 1E)
Shoot apical meristem cells of 7-day-old seedlings of both dodders are predominantly isodiametric, with centrally positioned large nuclei surrounded with a dense network of endoplasmic microtubules (Figure 1D)

Summary

Introduction

Parasitic plants are widespread weeds, agronomically and economically important in terms of harvest devastation. They need host plants as a source of nutrients, both organic and growth substances for their survival, and exude their metabolites into these host plants. Parasitic plants have developed various ways of attacking their hosts using a special adhesion/absorption organ called haustorium. Among 4,500 flowering parasitic plants (around 1% of all angiosperm species) (Yoshida et al, 2016), dodders (Cuscuta spp.) are represented by approximately 200 holo- and hemiparasitic species that contain trace amounts of chlorophyll and no RUBISCO activity (Kuijt and Toth, 1976; van der Kooij et al, 2000; Tešitel, 2016).

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