Parasitic plants are capable of causing a variety of effects to their hosts, including alterations in the process of wood formation. However, the majority of studies dealing with parasitic plant anatomy have focused on the host–parasite interface and the direct action of the haustorium, which is the organ responsible for attaching the parasite to the host. Considering this gap, we studied the anatomical and functional effects caused by a mistletoe species, Phoradendron crassifolium (Santalaceae), on the wood anatomy of the host tree Tapirira guianensis (Anacardiaceae). Both parasitized and non-parasitized branches were collected from host trees. Traditional wood anatomy procedures were employed, along with functionality experiments using the ascent of safranin solution through the xylem. Prior to the analysis, all sampled branches were divided in “upstream” and “downstream” portions, considering the direction of xylem sap flow inside the plant body. This design was chosen in order to avoid biased results derived from normal ontogeny-related wood anatomical and functional changes. Our results showed that infested wood expressed a higher density of embolized vessels, narrower vessel lumen diameter, higher vessel density, taller and wider rays, and fibers with thinner cell walls. All these responses were most conspicuous in the downstream sections of the parasitized branches. We propose that the wood anatomical and functional alterations were induced by the combination of water stress caused by water use by the parasite and consequent low turgor in differentiating cambial derivates; by unbalanced auxin/cytokinin concentrations originating at the infestation region due to phloem disruptions caused by the parasite’s penetration and action; and by higher than usual ethylene levels. Further analysis of hydraulic conductivity and hormonal changes in host branches are necessary to test this hypothesis.
INTRODUCTION Parasiticplants constitute about 1% of all angiosperm species and ~ 40% of them parasitize the aboveground parts of their host plants ( Norton & Carpenter 1998 ). Mistletoes are the predominant group of angiosperm shoot parasites. They are capable of attaching to and penetrating into
The parasitic plants of the genus Orobanche (broomrape) are important pathogens of numerous agricultural crops throughout the world. The understanding of biochemical mechanisms involved in the penetration of Orobanche haustorium into host root tissues faces difficulties due to the presence of microorganisms. Here we describe an aseptic in vitro system, in which normal broomrape seedlings infect host roots grown in culture, instead of the previously reported infection of intact host plants by Orobanche calli. This system is based on divided Petri plates with two different culture media: one part of the dish contains a rich medium suitable for the support of host root culture, the other part contains a medium with no organic nutrients and no hormones and is therefore suitable for infection of host roots by Orobanche. Roots that are supported by the first medium pass to the other side of the petri dish where they stimulate broomrape seed germination and are infected by the emerging broomrape seedlings.
Parasitic flowering plants are strikingly impressive and beautiful and hold many surprises of both general and scientific interest. Parasites also have great influence on the quality of human life when attacking crop plants. Some parasites have since early times appealed to our imagination and have been part of religious or folkloristic events and used as gifts to royalties. This beautifully illustrated book covers all parasitic families and most of the genera. It also discusses the establishment of the parasite, the structure and function of the nutrient absorption organ (haustorium), and how the parasites are pollinated and dispersed as well as their ecology, hosts, and evolution. The book is written in a mostly non-technical language and is provided with a glossary and explanatory boxes.
For additional information about this book, including some sample photographs, as well as a list of corrections that have been incorporated in the 2011 reprint, please visit the
author's web site.
Parasitic Flowering Plants was nominated by The Council on Botanical and Horticultural Libraries for the 2010 Annual Award for a Significant Work in Botanical or Horticular Literature, in the category ‘Technical Interest’.
Cariologia 1964 17 139 152
Laudi G. Ultrastructural researches on the plastids of parasiticplants. IV. Galls of Cuscuta australis G. Bot. Ital. 1968 102 1 19
Laudi G. Albertini A. Fissazione di CO 2 da parte di entomocecidi di Cuscuta australis G. Bot. Ital. 1965 72 351 354
Meloidogyne Göldi, 1892, or root-knot nematodes, represent a relatively small but economically important group of obligate plant pathogens. They are distributed worldwide and parasitize on almost every higher plant species. While reproducing and feeding within roots, they induce galls or root-knots and disorder the physiology of the infected plant, reducing crop yield and product quality.
More than eighty nominal species have been described worldwide, while twenty species have been detected in Europe so far. This book includes a historical review on the genus, followed by a revision of the European species, and completed with a study on one of the most characteristic morphological structures within the genus: the perineal pattern.
Workshop. Current Problems of Orobanche Research. Published by Institute for Wheat and Sunflower, General Toshevo, Albena, Bulgaria, pp. 147-153.
Losner-Goshen, D., Portnoy, V.H., Mayer, A.M., Joel, D.M. 1998. Pectolytic activity by the haustorium of the parasiticplant Orobanche L (Orobanchaceae
, parasiticplants, and disorders of unknown etiology affect this plant. Plant protection scientists, nematologists in particular, will find Chapter 2 on "Biologically Active Ingredients" and Chapter 3 on "Effects on viruses and organisms" extremely useful. Chapter 3 gives an overview of the effects of neem
which suffer from a deficiency of selective post-emergence herbicides ( Goldwasser et al. 2001 ). Thus, efforts are being made to produce cultivars that are resistant to post-applied herbicide and to the parasiticplant broomrape. For instance, chickpea breeders developed an EMS mutant population