Journal Article

The Endophytic System of Mediterranean <i>Cytinus</i> (Cytinaceae) Developing on Five Host Cistaceae Species

Clara De Vega, Pedro Luis Ortiz, Montserrat Arista and Salvador Talavera

in Annals of Botany

Published on behalf of The Annals of Botany Company

Volume 100, issue 6, pages 1209-1217
Published in print November 2007 | ISSN: 0305-7364
Published online September 2007 | e-ISSN: 1095-8290 | DOI: http://dx.doi.org/10.1093/aob/mcm217
The Endophytic System of Mediterranean Cytinus (Cytinaceae) Developing on Five Host Cistaceae Species

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Background and Aims

One of the most extreme manifestations of parasitism is found in the genus Cytinus, a holoparasite whose vegetative body is reduced to an endophytic system living within its host root. There are two species of Cytinus in the Mediterranean, C. hypocistis and C. ruber, which parasitize various genera of Cistaceae, one of the most characteristic families of the Mediterranean scrublands. The aim of this work is to describe the endophytic systems of C. hypocistis and C. ruber, and their tissue relationships with their host.

Methods

Roots from five different hosts infected with C. hypocistis and C. ruber were harvested, and examined by anatomical techniques under light microscopy to elucidate the characteristics of the endophytic system of Cytinus, and to determine if differences in endophytic systems occur between the two species and in response to different hosts.

Key Results

The endophyte structure is similar in both Cytinus species irrespective of the host species. In the initial stages of the endophyte, rows of parenchymal cells spread through the host pericyclic derivatives and phloem, and begin to generate small nodules in the outermost region of the host xylem. Later the nodules anastomose, and bands of parasitic tissue are formed. The host cambium continues to develop xylem tissue, and consequently the endophyte becomes enclosed within the xylem. The bands of parasitic tissue fuse to form a continuous sheath. This mature endophyte has well-developed vascular system with xylem and phloem, and forms sinkers with transfer cells that grow through the host xylem.

Conclusions

The endophytic system of Cytinus develops in all host root tissues and reaches its most mature stages in the host xylem. It is more complex than previously reported, showing parenchyma, xylem and phloem tissues. This is the first report of well-developed phloem in a holoparasitic endophytic species.

Keywords: Cistaceae; Cytinaceae; Cytinus hypocistis; Cytinus ruber; endophyte; Mediterranean region; parasitic plant; sieve elements; sinker; transfer cell

Journal Article.  5191 words.  Illustrated.

Subjects: Ecology and Conservation ; Evolutionary Biology ; Plant Sciences and Forestry

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