Topic
Orbea
About: Orbea is a research topic. Over the lifetime, 7 publications have been published within this topic receiving 136 citations.
Papers
TL;DR: Sequence data from two non-coding molecular markers support the traditional tribal affiliation of the taxon-rich stem-succulent stapeliads and most of the few related, leafy genera, which form a monophyletic group.
Abstract: Representatives of nearly all genera of the taxon-rich stem-succulent stapeliads and most of the few related, leafy genera were analyzed. Sequence data from two non-coding molecular markers (ITS region of nrDNA and trnT-L and trnL-F spacers as well as the trnL intron of cpDNA) support the traditional tribal affiliation of the genera, which form a monophyletic group. This monophylum breaks into a basal Neoschumannia/Anisotoma/Riocreuxia/Sisyranthus nk;clade, from which the core Ceropegieae are derived. The four Ceropegia species included are not monophyletic, and their relationship to Brachystelma changes depending on the marker studied. The stem succulent taxa fall in a number of well supported, but unresolved clades, the most prominent being the predominantly southern African clade comprising Orbea, Stapelia and some other genera. The most derived taxa of NE Africa, Duvaliandra and White-sloanea, are basal to this southern African clade. The other clades comprise the more basal genera of stem-succulent stapeliads, including the members of the Caralluma complex. Of the 17 genera accepted by Plowes for the Caralluma complex, seven are recognized: Caralluma, Apteranthes, Australluma, Boucerosia, Caudanthera, Desmidorchis and Monolluma. New combinations are proposed in 15 cases; Caralluma adscendens var. geniculata is raised to specific rank. Anomalluma is reinstated, and Pseudolithos mccoyi is transfered to it. A broadened concept for Orbea (incl. Angolluma and Orbeopsis) is recognized, but Orbeanthus is kept separate. The monotypic Ballyanthus, recently separated from Orbea, is nested within Duvalia. Piaranthus (incl. Huerniopsis) is monophyletic. The bitypic Notechidnopsis is reduced to the type species, N. tessellata, while N. columnaris is transferred to a new genus, Richtersveldia.
92 citations
TL;DR: This study measured the impact of an introduced plant species, Orbea variegata (African carrion flower), upon the dominant shrub Atriplex vesicaria (bladder saltbush) and the annual plant community in chenopod shrublands of South Australia to suggest that OrbeA has a severe detrimental effect on the native vegetation.
47 citations
1 Jan 2002
17 citations
15 Nov 2015
TL;DR: The results indicated that superoxide dismutase (SOD) is not playing an important role in eliminating O2− in PI tissues and other antioxidant enzymes were lower compared with the healthy tissues.
Abstract: The present study reports on reactive oxygen species (ROS), antioxidant enzyme activities, electrolyte leakage and levels of abscisic acid (ABA) in healthy and phytoplasma infected (PI) tissues of Euphorbia coerulescens and Orbea gigantea. Histochemical staining for ROS indicated that PI tissues possess higher levels of hydrogen peroxide (H2O2) rather than superoxide (O2 ·-) as compared with healthy tissues in both plant species. The results indicated that superoxide dismutase (SOD) is not playing an important role in eliminating O2− in PI tissues. This was confirmed by a significantly decreased activity of SOD and a non-significant difference in O2 ·- content in PI tissues as compared to healthy tissues in both plant species. Peroxidase (POX) activity was significantly decreased while polyphenol oxidase (PPO) significantly increased in PI tissues compared with healthy tissues in both plant species. PI tissues was associated with a significant increase in catalase (CAT) and ascorbate peroxidase (APX) activity in E. coerulescens and a significant increase in glutathione reductase (GR) activity in O. gigantea. However, other antioxidant enzymes were lower compared with the healthy tissues. In both plant species, electrolyte leakage was significantly increased in PI tissues compared to healthy tissues.ABA level was decreased in PI tissues as compared to healthy tissues.
6 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2015 | 1 |
| 2013 | 1 |
| 2008 | 1 |
| 2002 | 2 |
| 2000 | 1 |
| 1999 | 1 |