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Acacia gerrardii Benth. tree. a Overview of a healthy tree. b Overview of a tree infected with Plicosepalus curviflorus mistletoe. c Close-up view showing how a mistletoe is attached to the host tree. d Close-up view of a healthy branch. e Low infected branch with mistletoe. f Highly infected branch. g Flowering mistletoe with red colored flowers
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Mistletoes are epiphytic hemiparasitic plants that are known to negatively affect the growth of their hosts, increase tree mortality, and as a consequence change the community dynamics. Mistletoe alters the mineral nutrition of the host and the nutrient cycle in the soil. In the present study, the elemental nutrient status is described for Acacia a...
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Loranthaceae family includes hemiparasitic members which are seen invading a wide range of commercial crops. Helicanthes elasticus (Desv.) Danser is very common on mango trees. Though parasitic in nature, this mistletoe is also medicinally important as fetoprotective, against vesicular calculi and kidney infections. This study is an attempt to docu...
Mistletoe Dendrophthoe pentandra (L.)Miq is a parasitic plant commonly found parasitizing and infesting medicinal plants such as Cassia fistula L. This research aimed to investigate the infestation of D. pentandra on C. fistula on various trees canopy shading, infested host number and plant diversity. Study was conducted in Purwodadi Botanic Garden...
Citations
... The woody parasites P. acaciae and P. curviflorus are widespread parasites of Vachellia [48]. Al-Rowaily et al. [24] reported a high infection incidence of P. curviflorus in different species of Vachellia genus in Saudi Arabia's southern and western areas, resulting in ecosystem degradation and loss of diversity and soil nutrients. Other studies demonstrated that mistletoe preferentially infects massive trees over small ones [64,65]. ...
The ecology and diversity of flowering parasitic plants and their hosts are poorly investigated and usually ignored in Saudi Arabian plant communities. Therefore, this work aimed at assessing the ecology and diversity of parasitic plants and their hosts along an elevation gradient in the Al-Baha region (1300–2400 m.a.s.l.). Different quantitative vegetation parameters were applied to analyze the collected data. Eight parasitic plants from six genera and four families were identified along the gradient, with 67% of them being zoochorously dispersed species. They accounted for approximately 23.5% (8 out of 34) of those found throughout Saudi Arabia. Perennials, stem hemiparasites, and biregional taxa accounted for around 62.5% of the total parasites, whereas indigenous species accounted for 75%. The dominant family of parasitic species was Loranthaceae (50%), and Phragmanthera austroarabica A.G.Mill. & J.A.Nyberg was the most important species (IVI = 107.28). Orobanche cernua Loefl. and Loranthella deflersii (Tiegh.) S.Blanco & C.E.Wetzel were restricted to the dry zone (low elevation) only, while the other parasites were distributed across the surveyed region. Twenty-three host plants were identified throughout the study region. About 83% of them were phanerophytes and bioregional plants, with 91% being perennial species. The prevalent host plant family across all sites was Fabaceae, with Nicotina glauca Graham being the most important host species (IVI = 32.44%). P. austroarabica and Plicosepalus curviflorus Tiegh. preferred Vachellias as host plants, while Vachellia flava (Forssk.) Kyal. & Boatwr. was the heavily infected host by P. austroarabica. P. austroarabica had a broad spectrum of host range (13 host plants), while O. cernua had a very narrow host range (only Rumex nervosus Vahl). Individual parasite and host species were markedly more abundant in the wet zone than in the low-altitude dry zone. Further research is needed to fully understand such distinctive groups of plants and their negative and positive ecological consequences on plant biodiversity and natural ecosystems.
... Many mistletoe-host comparative studies on mineral nutrients have been conducted over the past 40 yr (Lamont, 1983;Ehleringer et al., 1986;Glatzel & Geils, 2009;Scalon et al., 2013;Al-Rowaily et al., 2020). Theory based on such studies has posited that the higher transpiration rates of mistletoes than their hosts serve a nutrient-gathering role since mistletoes have evolved a lower energetic investment in haustoria than would be the case for free-standing plants that require structural and conducting roots (Schulze et al., 1991). ...
Mistletoes play important roles in biogeochemical cycles. Although many studies have compared nutrient concentrations between mistletoes and their hosts, no general patterns have been found and the nutrient uptake mechanisms in mistletoes have not been fully resolved.
To address the water and nutrient relations in mistletoes compared with their hosts, we measured 11 nutrient elements, two isotope ratios and two leaf morphological traits for 11 mistletoe and 104 host species from four sites across a large environmental gradient in southwest China.
Mistletoes had significantly higher phosphorus, potassium, and boron concentrations, nitrogen isotope ratio, and lower carbon isotope ratio (δ¹³C) indicative of lower water‐use efficiency than hosts, but other elements were similar to those in hosts. Sites explained most of the variation in the multidimensional trait space. With increasing host nitrogen concentration, both mistletoe δ¹³C and the difference between mistletoe and host δ¹³C increased, providing evidence to support the ‘nitrogen parasitism hypothesis’. Host nutrient concentrations were the best predictors for that of the mistletoe nutrient elements in most cases.
Our results highlight the important roles of environmental conditions and host nutrient status in determining mistletoe nutrient pools, which together explain their trophic interactions with hosts in subtropical and tropical ecosystems.
... Parasites can have indirect facilitative effects by increasing the quantity and quality of soil litter and nutrients (Ndagurwa et al., 2014;Ndagurwa et al., 2016;Al-Rowaily et al., 2020), modifying solar irradiance (Mellado & Zamora, 2017;Chu et al., 2021) and soil temperatures and humidity (Maponga et al., 2021) under their host's canopy. ...
Questions
In this study we investigated the direct effect of the shrub Juniperus oxycedrus s.l. on Mediterranean woody species regeneration, and how this interaction can be modified by the juniper habit, the forest canopy and/or infestation of the juniper by the plant parasite Arceuthobium oxycedri . We also aimed at identifying species response groups in relation to their ecological requirements and successional strategies.
Location
North of Mount Lebanon, in Horsch Ehden natural reserve, a humid montane Mediterranean forest.
Methods
We compared the regeneration of all occurring woody species below and outside 111 Juniperus oxycedrus canopies using the random pair sampling method. We calculated eight relative interaction intensity indexes (RII Juniper ) corresponding to the eight treatment combinations of the three factors: forest canopy (forest/gap), mistletoe infestation (with/without) and juniper habit (spreading/erect). We analyzed the RII values at three different levels: community (all species grouped), species group and species.
Results
Overall, the regeneration of the woody community was facilitated by Juniperus oxycedrus . However, the forest cover significantly reduced the facilitative effect of Juniperus oxycedrus when the latter was not infested by Arceuthobium oxycedri . We identified three species response groups (A: highly facilitated; B: slightly facilitated to neutral; and C: neutral) determined by their response to both Juniperus oxycedrus canopy and forest cover. The most facilitated species were shade‐tolerant/drought‐intolerant late‐successional species.
Conclusions
The results suggest the importance of shade tolerance in the complex mechanism of forest regeneration that is also affected by a parasite plant ( Arceuthobium oxycedri ), which boosts regeneration dynamics under forest cover by reducing shrub canopy cover.
... They extract nutrients and water from the host plant for their survival [22]. Although their leaves may photosynthesize, they do so at a slower rate than their hosts [23]. Ahmad et al. [24] highlighted that they contain a functionally low amount of chlorophyll, and their low capability for photosynthesis explains their capability to adapt to dry conditions. ...
A cost-effective, alternative protein and mineral source such as the Viscum species can be key to livestock production. Viscum spp. are used as feed in many semi-arid and arid regions globally, particularly during feed shortages. The species’ feeding value, and their pharmaceutical attributes, have been recognized worldwide, albeit with variation in nutritive value from one host to another. The antinutritional factors found in Viscum spp. may benefit livestock when consumed in moderation due to their immunomodulatory, proapoptotic, and antimicrobial properties. The Vachellia species are known to be the common hosts for Viscum spp. Further, even though Viscum spp. inhibit host tree
development by reducing carbon absorption and the host tree’s carbohydrates, the efforts to regulate their infestation should not result in the plant’s total eradication due to the benefits to livestock (as well as in fodder and medicine). This review will help to improve understanding of Viscum species control measures, while also increasing the productivity of ruminants.
... Mistletoes on tree canopies have been shown to increase the availability of nutrients through augmented litterfall, thus further enhancing heterogeneity and increasing species richness of understory assemblages (March and Watson, 2007;Muvengwi et al., 2015;Ndagurwa et al., 2016Ndagurwa et al., , 2018Hódar et al., 2018;Al-Rowaily et al., 2020). For example, Ndagurwa et al. (2013) showed that mistletoes produced significantly more litter than their host, Vachellia karroo (Hayne) Banfi & Galasso trees, thus increasing nutrients within the canopy patches of mistletoe-infected trees. ...
... soil fertility associated with mistletoe-infected trees (Ndagurwa et al., 2020(Ndagurwa et al., , 2018Hódar et al., 2018;Monteiro et al., 2020;Maponga et al., 2021). High mistletoe infection canopy patches have higher soil moisture content, temperature, and litter contents which are associated with higher microbial activity, accelerated litter decomposition, and elevated nutrient cycling rates (Al-Rowaily et al., 2020;Ndagurwa et al., 2020). The higher affinity and abundance of S. pyramidalis, A. africanus, Z. mucronata and F. virosa for high mistletoe-infection canopy patches confirm that these patches are resourceful. ...
... This study shows that mistletoes improve soil resources which in turn influence the plant species composition and the effects vary with mistletoe-infection degrees within their host canopy patches. In addition, by weakening the host through competition for resources and altering the host canopy structure by increasing light incidence, mistletoes further increase spatial heterogeneity underneath mistletoe-infected trees (Sala et al., 2001;March and Watson, 2007;Mathiasen et al., 2008;Muvengwi et al., 2015;Ndagurwa et al., 2016Ndagurwa et al., , 2018Mellado et al., , 2017Hódar et al., 2018;Al-Rowaily et al., 2020). These results indicate that considering varying levels of mistletoe infection (e.g., Maponga, 2021;Ndagurwa et al., 2014 and this study) may be more revealing than comparing infected vs. uninfected hosts. ...
In savanna ecosystems, tree canopy patches differ in plant species composition compared to adjacent intercanopy spaces due to different levels of resource availabilities. Mistletoes further augment nutrients underneath tree canopies whilst reducing their hosts’ competitive edge, thus providing more resources and creating patches that support higher understory species richness. However, little is known on how understory species and functional trait assemblages, in both canopy and intercanopy spaces, are affected by varying overstory mistletoe infection intensities. This study investigated how functional and species diversity/composition varied within and between canopy patches and intercanopy spaces of high- and low mistletoe-infected Vachellia karroo trees. The affinity of individual species to the different canopy patches and intercanopy spaces was also assessed. Microhabitats had significantly different species compositions. A higher proportion of species (34%) showed a strong positive affinity towards canopy patches whilst intercanopy spaces were strongly associated with only 9% of recorded species, indicating greater dominance of some species there. Generally, subcanopy patches had significantly higher species richness and diversity, and functional diversity, compared to adjacent intercanopy spaces. These variables increased with increasing mistletoe infection, thus grass, forb and tree species diversity were 17% to 43% higher, and functional diversity indices were 0.5% to 28% greater in high- compared to low mistletoe-infection canopy patches. Furthermore, species richness and diversity of C3, C4, annual and perennial plants were 1.27 to 3.13-fold higher within canopy patches compared to intercanopy spaces and 1.28 to 1.74-fold greater within high- compared to low mistletoe-infection microhabitats. Consequently, high mistletoe-infection canopy patches had between 1.08 to 3.76-fold greater species richness and diversity of C3, C4, annual and perennial plants compared to the other three microhabitats. Our findings suggest that by enhancing spatial heterogeneity, variations in mistletoe infection facilitate biodiversity and to a lesser extent vegetation structural diversity in these semi-arid savannas.
... They observed that potassium decreased in Acacia trees proportionally to the degree of infection. Compared to uninfected trees, potassium levels decreased by 52% [9]. ...
In Mexico, mistletoes have several applications in traditional medicine due to the great variety of compounds with biological activities that have not been characterized to date. The goals of the present study are to analyze the composition of minerals and phytochemical compounds in Mexican mistletoes Phoradendron bollanum and Viscum album subs. austriacum qualitatively and quantitatively, identify the compounds using HPLC-MS, and assess the antimicrobial potential in phytopathogenic microorganism control. Mineral content was evaluated with X-ray fluorescence. Three types of extracts were prepared: ethanol, water, and aqueous 150 mM sodium chloride solution. Characterization was carried out using qualitative tests for phytochemical compound groups, analytical methods for proteins, reducing sugars, total phenol, flavonoids quantification, and HPLC-MS for compound identification. The antimicrobial activity of mistletoe’s liquid extracts was evaluated by microplate assay. K and Ca minerals were observed in both mistletoes. A qualitative test demonstrated alkaloids, carbohydrates, saponins, flavonoids, tannins, and quinones. Ethanolic extract showed flavonoids, 3845 ± 69 and 3067 ± 17.2 mg QE/g for Phoradendron bollanum and Viscum album subs. austriacum, respectively, while aqueous extracts showed a total phenol content of 65 ± 6.9 and 90 ± 1.19 mg GAE/g Phoradendron bollanum and Viscum album subs. austriacum, respectively. HPLC-MS identified largely hydroxycinnamic acids and methoxycinnamic acids. Clavibacter michiganenses was successfully inhibited by aqueous extract of both mistletoes.
... According to the RDA analysis, soil temperature, species richness, and soil pH all affected soil nutrient contents (Fig. 6b). Previous research showed that soil C and N is mainly derived from litter returning to the soil after plant death [18][19][20]. The lower soil temperature along the altitudinal gradient reduced the rate of the litter decomposition, inhibiting the C and N inputs. ...
Knowledge of altitudinal patterns in soil C, N and P distribution is important for understanding biogeochemical processes in mountainous forests, yet the influence of slope aspects on soil stoichiometry has been largely neglected in previous studies. In this paper, a total number of 150 topsoil samples at four altitudes (3700, 3900, 4100, 4380 m a.s.l.) on sunny and shady slopes of Sygera mountains in the Southeastern Tibet were collected. Soil C, N and P contents, and pH, were measured. Soil temperature, moisture and richness of plant species were investigated at each sampling site. The results showed that: 1) in sunny slope, soil C, N and P concentrations increased with the increase in altitude, whereas soil C:N, C:P, and N:P decreased along the altitudinal gradient on s. Soil moisture was the main regulator of soil nutrition and stoichiometric ratios. 2) In shady slope, soil C and N contents had no significant difference along the altitudinal gradient except the higher values at low altitude, whereas soil P increased first and then decreased. Soil C:N increased with the increase in altitude, whereas C:P and N:P decreased first and then increased. Soil temperature and species richness were the main factors influencing soil nutrition and stoichiometric ratios. 3) Decoupling of soil C:N:P stoichiometry was observed in shady slope owing to changes in soil pH and temperature. 4) The rich contents of soil C and P were observed at two slopes along the altitudinal gradient, and high capacity of N supply existed at the topsoil in shady slope. These results suggested that slope aspect plays an important role in shaping the altitudinal pattern of soil C:N:P stoichiometry in mountainous forests.
Purpose
Parasitic plants are important drivers of plant communities and even ecosystems through parasitic plant-host interactions, but little is known about parasitism effects on host belowground soil resources and microbial communities.
Methods
We investigated the soil nutrients and the root-associated (root zone, rhizosphere, root endosphere and root nodule) bacterial communities of soybean (Glycine max) with different parasitism statuses (noninhibitory and inhibitory interactions) induced by plant dodder (Cuscuta chinensis) in soils from three different origins.
Results
Our results showed that inhibitory parasitism, rather than noninhibitory parasitism, significantly promoted soil multinutrient accumulation in the soybean root zone. Parasitism, especially inhibitory parasitism, increased the bacterial enrichment in the closely root-associated compartments (rhizosphere, root endosphere and root nodule) of soybean, including the rhizobial taxa. Additionally, the closely root-associated bacterial communities of soybean with inhibitory parasitism had higher soil environmental sensitivity than that of other soybeans, especially the nodule community to soil nitrate nitrogen. Network analysis indicated that inhibitory parasitism led to higher complexity and instability of the closely root-associated bacterial communities. Structural equation model showed that the effects of root zone community and key soil factor on the positive associations of the closely root-associated bacterial communities varied with parasitism status.
Conclusions
These results provide important perspectives for understanding the effects of parasitic plant-host interactions on the dynamics of host belowground microbial communities and soil nutrient cycling in agricultural and natural ecosystems.
Mistletoes are emerging as important co-contributors to tree mortality across terrestrial ecosystems, particularly when infected trees are stressed by water limitations during drought. While the mechanistic effects of mistletoe infection on host physiology are reasonably well understood, quantifying the effects of mistletoe infection on stand productivity, canopy turnover and ecosystem structure remains challenging. Moreover, the potential devastating effect of mistletoe infection on host survival has distracted from the challenges that mistletoe populations are facing when increasing drought and heat stress threaten their survival in healthy populations. We coupled intensive observations of mistletoe population dynamics with measurements of host tree stem growth, canopy turnover and stand structure in a severely infected temperate eucalypt woodland to monitor how mistletoe infection alters aboveground biomass distribution and to assess ecosystem recovery from severe mistletoe infection during and after a three-year drought. We show that severe mistletoe infection reduces live standing biomass and canopy volume, with mistletoe leaves contributing up to 43% to total stand litter fall. We further identified that a mistletoe:host leaf area ratio above 60% significantly reduced basal area growth, which provides a threshold for productivity losses due to mistletoe infection in eucalypts. Yet, concurrent increases in basal area and the thickening of canopy volume indicate that host trees recover rapidly after the three-year drought combined with record summer heat nearly extinguished the mistletoe population. How common, or how widespread such dynamic changes in mistletoe population dynamics are within Australian or global ecosystems remains subject to further exploration.
