Development of phloem connection between the parasitic plant Orobanche cumana and its host sunflower
Orobanche cumana is a root parasitic plant causing considerable yield losses in sunflower cultivation. The holoparasite fulfills its entire demand for water, minerals, and organic nutrients from the host’s vascular system. In this study, the ultrastructure of the phloem connection between the hausto...
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Published in | Protoplasma Vol. 256; no. 5; pp. 1385 - 1397 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Vienna
Springer Vienna
01.09.2019
Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | Orobanche cumana
is a root parasitic plant causing considerable yield losses in sunflower cultivation. The holoparasite fulfills its entire demand for water, minerals, and organic nutrients from the host’s vascular system. In this study, the ultrastructure of the phloem connection between the haustorium of young
O. cumana
tubercles and the sunflower root has been examined for the first time. Parasite and host tissues were intermingled at the contact site and difficult to distinguish, but sieve-tube elements of
O. cumana
and sunflower could be differentiated according to their plastid ultrastructure. While
O. cumana
sieve-element plastids were larger, often irregular in shape and contained few, small starch inclusions, sieve-element plastids of the host were significantly smaller, always roundish with more and larger starch inclusions. This made it possible to trace the exact contact site of host and parasite sieve elements to show a direct symplastic phloem connection between the two species. The interspecific sieve plate showed more callose on the host side. This allowed detection of newly formed plasmodesmata between host sieve-tube elements and parenchymatic parasite cells, thus showing that undifferentiated cells of the parasite could connect to fully differentiated sieve elements of sunflower. Furthermore, the arrangement of phloem within the
O. cumana
tubercle as well as differences in sieve-element plastid ultrastructure during shoot development in
O. cumana
were investigated and are discussed in this paper. |
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ISSN: | 0033-183X 1615-6102 |
DOI: | 10.1007/s00709-019-01393-z |