Coleus Blumei Research Articles

Coleus blumei viroid 2

This datasheet on Coleus blumei viroid 2 covers Identity, Distribution, Hosts/Species Affected, Further Information.

The Effect of Natural Pellet Binders and Dosage to Produce Pellet made of Miana Plant (Plectranthus scutellarioides, (L.) R. Br.) as Poultry Feedstuffs

The Effect of Natural Pellet Binders and Dosage to Produce Pellet made of Miana Plant (Plectranthus scutellarioides, (L.) R. Br.) as Poultry Feedstuffs

THE VIRTUAL SCREENING OF SECONDARY METABOLITES OF MIANA LEAVES (Plectranthus scutellarioides (L) R. Br) AGAINST PLASMODIUM FALCIPARUM LACTATE DEHYDROGENASE ENZYME (PfLDH)

Malaria is a deadly disease that still occurs in some tropical countries. Medicines derived from plant parts have long been used as herbal medicines to treat malaria as part of Indonesian traditional medicine practice. Miana has been used as one of the antimalarial herbs by the South Sulawesi community. This study describes the in-silico study by tethering the secondary metabolite compound molecule of miana leaf (Plectranthus scutellarioides (L.) R.Br.) To the Plasmodium falciparum lactate dehydrogenase (PDB ID code: 1CET) as the first-line test to determine the antimalarial activity of Miana leaves. The results showed that the free energy binding value of 4 secondary metabolites of miana leaves, namely Scutellarioidone A (-6.32 kcal/mol), Scutellarioidone D (-6.06 kcal/mol), Coleon O (-6.07 kcal/mol), Fredericone B (-6.13 kcal/mol), was better than its natural ligands, Chloroquine (-5.89 kcal/mol). From the visualization of the docking results, all compounds have hydrogen bonds with different amino acid residues. Based on the results of predictions of pharmacokinetics, toxicity, and Lipinski's rule of five, all secondary metabolites from Miana leaves meet the criteria as a promising drug. However, some compounds can pose a safety risk. From the overall computational analysis, it can be predicted that the Scutellarioidone D can be used as a candidate for antimalarial drugs.

 Coleus (Lamiaceae) in Peninsular Malaysia including two new species.

In Peninsular Malaysia, Coleus is represented by five species. Two, C.hairulii Kiew and C.rafidahiae Kiew, are new species. Both are narrowly endemic and restricted to limestone hills as is C.kunstleri (Prain) A.J.Paton. All three are Critically Endangered. Coleusscutellarioides (L.) Benth., although widespread, is probably not indigenous. It is also a common ornamental, while C.monostachyus (P.Beauv.) A.J.Paton is a recent introduction that has spread rapidly and threatens to become a troublesome weed.

First report of Coleus blumei viroid 1 in commercial Coleus blumei in the United States.

Coleus scutellarioides (syn. Coleus blumei) is a widely grown evergreen ornamental plant valued for its highly decorative variegated leaves. Six viroids, named Coleus blumei viroid 1 to 6 (CbVd-1 to -6) have been identified in coleus plants in many countries of the world (Nie and Singh 2017), including Canada (Smith et al. 2018). However there have been no reports of Coleus blumei viroids occurring in the U.S.A. (Nie and Singh 2017). In April 2021, leaf tissue samples from 27 cultivars of C. blumei, one plant of each, were submitted to the University of Idaho laboratory from a commercial nursery located in Oregon to screen for the presence of viroids. The sampled plants were selected randomly and no symptoms were apparent in any of the samples. Total nucleic acids were extracted from each sample (Dellaporta et al. 1983) and used in reverse-transcription (RT)-PCR tests (Jiang et al. 2011) for the CbVd-1 and CbVd-5 with the universal primer pair CbVds-P1/P2, which amplifies the complete genome of all members in the genus Coleviroid (Jiang et al. 2011), and two additional primer pairs, CbVd1-F1/R1 and CbVd5-F1/R1, specific for CbVd-1 and CbVd-5, respectively (Smith et al. 2018). Five C. blumei plants (cvs Fire Mountain, Lovebird, Smokey Rose, Marrakesh, and Nutmeg) were positive for a coleviroid based on the observation of the single 250-nt band in the RT-PCR test with CbVds-P1/P2 primers. Two of these CbVd-1 positive plants (cvs Lovebird and Nutmeg) were also positive for CbVd-1 based on the presence of a single 150-nt band in the RT-PCR assay with CbVd1-F1/R1 primers. One plant (cv Jigsaw) was positive for CbVd-1, i.e. showing the 150-nt band in RT-PCR with CbVd1-F1/R1 primers, but did not show the ca. 250-bp band in RT-PCR with primers CbVds-P1/P2. None of the tested plants were positive for CbVd-5, either with the specific, or universal primers. All coleviroid- and CbVd-1-specific PCR products were sequenced directly using the Sanger methodology, and revealed whole genomes for five isolates of CbVd-1 from Oregon, U.S.A. The genomes of the five CbVd-1 isolates displayed 96.9-100% identity among each other and 96.0-100% identity to the CbVd-1 sequences available in GenBank. Because the sequences from cvs Lovebird, Marrakesh, and Nutmeg, were found 100% identical, one sequence was deposited in GenBank (MZ326145). Two other sequences, from cvs Fire Mountain and Smokey Rose, were deposited in the GenBank under accession numbers MZ326144 and MZ326146, respectively. To the best of our knowledge, this is the first report of CbVd-1 in the United States.

Compound Analysis and Genetic Study of Selected Plectranthus scutellarioides Varieties from Indonesia

Background: Plectranthus scutellarioides is one of medicinal plants in Indonesia, which has several hundred varieties but only one is known by local people as medicine. Objective: Six varieties of Plectranthus scutellarioides were analyzed for their total flavonoid content, chemical compound, and moleculer genetic. Methods: TFCs were analyzed using AlCl3 colorimetric method, chemical compounds were identified using TLC-scanning densitometer, GC-MS, and FTIR, moleculer genetic were observed using DNA barcoding rbcL gene. Results: The TFCs of trailing psycholeus, and flamingo varieties were higher than the other varieties. TLC-scanner densitometer showed that color blaze dark star, trailing psycholeus, and trailing queen had similar profiles, as did beale street, trailing rose, and flamingo. The GCMS results showed notable difference in trailing psycholeus and trailing queen which have 2-oleoylglycerol and 9(E),11(E)-conjugated linoleic acid in larger amounts than others, respectively. Multivariate analysis of the FTIR spectra showed the closeness of all varieties, except for beale street which had the lowest similarity with the others. Despite that, genetic studies using the rbcL gene and comparing the results with the P. scutellarioides gene in the database (MW538954.1) showed beale street was the most similar (99.52%). The phylogenetic analysis showed that beale street and trailing psycholeus have the highest similarity among others. Conclusions: There is a slight difference in chemical composition between varieties as well as the genetic. Therefore, quality control or standardisation is needed in the use of this plant as a traditional medicine.

Analysis of potential and feasibility level of simarjarunjung nature tourism as part of Lake Toba national super priority destination

Simalungun Regency, North Sumatra Province, has Simarjarungjung Nature Tourism area which is one of the attractions along the north side of Lake Toba. The Simarjarunjung area is an alternative destination for tourists because this area is a location that can be used as a vantage point to see the landscape of Lake Toba, as well as a stopover location for tourists visiting various attractions in the Lake Toba surrounding area. The objective of this study is to analyze potential of the natural tourism objects and feasibility level of developing the natural attractions in the Simarjarunjung area. The analytical method used in this study refers to the guidelines for Operational Area Analysis of Natural Tourism Objects and Attractions (henceforth referred to as ADO-ODTWA) issued by the Director General of Forest Protection and Nature Conservation (henceforth referred to as Dirjen PHKA) in 2003. Data are collected through surveys by direct observation and interviews using questionnaires to visitors. The Simarjarunjung Nature Tourism Area has several potential natural attractions, first, beauty of the natural scenery where visitors can look at the view of Lake Toba and green hills surrounding it and experience the microclimate of the mountains with cool, clean and comfortable air. Second; potential diversity of exotic flora and fauna such as pine (Pinus merkussi), red shoots (Syzygium oleana), various orchid plants, various flower plants, especially miana (Coleus scutellarioides), long-tailed monkey (M fascicularis) and eagle (Haliastur sp); and the third, natural recreational rides such as camping ground and parks. The results show that the potential objects in the Simarjarunjung Nature Tourism area are classified into “feasible to develop” category into tourism with a feasibility index of 79.56.

EFFECTIVENESS OF UTILIZING MIANA LEAVES (COLEUS SCUTTELARIOIDES (L) BENTH) ON THE GROWTH OF ESCHERICHIA BACTERIA (E. COLI) AS A CAUSE OF DIARRHEA AT DRINKING WATER REFILL CENTER

This research aims to determine the inhibition and effectiveness of using miana leaf extract against the growth of E. coli bacteria that causes diarrhea. This study uses experimental research with samples of miana leaves extracted and E. coli bacteria and then uses the Kruskal-Wallis test with Mann-Whitney analysis to test the hypothesis. The results showed differences in the inhibition between miana leaves extract concentrations of 15%, 30%, 50%, and 90% of the growth of E. coli bacteria with Asymp values. Sig = 0.017. The most effective concentration of miana leaf extract in influencing E. coli bacteria was an extract concentration of 90% with an inhibition zone diameter of 31.27 mm. There was a significant difference in the inhibition between miana leaf extract (Coleus scutellarioides (L) Benth) on the growth of E. coli bacteria at 12, 15 & 18 hours, 20 hours, and 24 hours, with Asymp values. Sig = 0.000. Results an increase in the inhibition zone, and the highest inhibition occurred during the 24 hours, namely at a very strong 90% extract concentration. This finding proves that the compounds contained in miana leaf extract can inhibit the growth of E. coli bacteria. This finding has implications for refill drinking water managers to utilize miana leaf extract to avoid E. coli bacteria as the main cause of diarrhea.

Isolation and Characterization of Stigmasterol and β-sitosterol from Plectranthus scutellarioides var. color blaze dark star and Cytotoxicity of Its Fraction

Plectranthus scutellarioides is one of medicinal plants in Indonesia, traditionally known as iler/miana/jawer kotok. Due to a large number of varieties, certain varieties of P. scutellarioides have not been extensively studied. This study focused on the isolations of two phytosterols, stigmasterol and β-sitosterol, which were characterized by various 1D and 2D NMR analyses, from the ethyl acetate extract of P. scutellarioides var. color blaze dark star. Cytotoxicity of the ethyl acetate extract and some selected fractions were evaluated against A549, MDA-MB-231, MCF-7, KB, and KB-Vin cell lines using SRB (Sulforhodamine B) method. Among all tested sample, fractions 15 and 17 have significantly inhibited cell growth with IC50 of 14.3-24.3 µg/mL and 7.3-14.1 µg/mL, respectively.

Coleus blumei viroid 7: a novel viroid resulting from genome recombination between Coleus blumei viroids 1 and 5.

The genus Coleviroid, family Pospiviroidae, comprises six known viroids, all infecting Plectranthus scutellarioides (Coleus blumei; coleus). In 2017, a novel viroid-like RNA sequence that shares ca. 65% identity with Coleus blumei viroid 1 (CbVd-1) was identified in a coleus cultivar infected by multiple coleviroids. Further sequence and secondary structure analyses are consistent with the discovery of a seventh viroid in the genus Coleviroid: tentatively named "Coleus blumei viroid 7" (CbVd-7). The viroid appears to be the product of a natural recombination event between CbVd-1 and Coleus blumei viroid 5. We prove CbVd-7 to be infectious and in turn demonstrate the ability of all known coleviroid left- and right-arm segments to recombine. With a length of 234 nucleotides, this is the smallest viroid described to date.

Quantitative dissection of color patterning in the foliar ornamental coleus.

Coleus (Coleus scutellarioides) is a popular ornamental plant that exhibits a diverse array of foliar color patterns. New cultivars are currently hand selected by both amateur and experienced plant breeders. In this study, we reimagine breeding for color patterning using a quantitative color analysis framework. Despite impressive advances in high-throughput data collection and processing, complex color patterns remain challenging to extract from image datasets. Using a phenotyping approach called “ColourQuant,” we extract and analyze pigmentation patterns from one of the largest coleus breeding populations in the world. Working with this massive dataset, we can analyze quantitative relationships between maternal plants and their progeny, identify features that underlie breeder-selections, and collect and compare public input on trait preferences. This study is one of the most comprehensive explorations into complex color patterning in plant biology and provides insights and tools for exploring the color pallet of the plant kingdom.

Spray Volume and Frequency Impacts on Insecticide Efficacy Against the Citrus Mealybug (Hemiptera: Pseudococcidae) on Coleus under Greenhouse Conditions

Abstract The citrus mealybug Planococcus citri (Risso) (Hemiptera: Pseudococcidae) is a major insect pest of greenhouse-grown horticultural crops. The citrus mealybug causes direct damage by feeding on plant leaves, stems, flowers, and fruits, which can lead to substantial economic losses. Consequently, insecticides are used to suppress citrus mealybug populations in greenhouse production systems. However, application factors may influence the efficacy of insecticides in suppressing citrus mealybug populations. Therefore, experiments were conducted under greenhouse conditions to determine the effect of spray volume and application frequency on insecticide efficacy against the citrus mealybug feeding on coleus, Solenostemon scutellarioides (L.) Codd, plants. Four spray volumes (15, 25, 50, and 75 mL), 2 application frequencies (1 or 2 applications), and 3 insecticides (acetamiprid [TriStar®], flonicamid [Aria®], and cyfluthrin [Decathlon®]), each with a different mode of action, were tested. Based on mean percent citrus mealybug mortality, acetamiprid was more effective against citrus mealybugs than flonicamid or cyfluthrin. In the spray volume experiments, acetamiprid applied at 75 mL to each plant resulted in a mean percent citrus mealybug mortality of over 70%. In contrast, flonicamid and cyfluthrin resulted in less than 50% mean citrus mealybug mortality across all experiments. In the application frequency experiments, two spray applications did not result in a significantly higher mean citrus mealybug mortality than one spray application. Our study emphasizes the importance of spray volume and application frequency when using insecticides to suppress citrus mealybug populations.

Effects of Growth Substrate on Greenhouse Gas Emissions from Three Annual Species

AbstractPrevious work by these authors have quantified cumulative greenhouse gas (GHG) emissions for several woody and herbaceous perennial species, in interaction with several standard best management practices (container size, fertilizer application and irrigation delivery methods, and light level). In this study, the greenhouse production of three annual species [coleus (Solenostemon scutellarioides Thonn. ‘Redhead'), vinca (Catharanthus roseus L. ‘Cooler Grape'), and impatiens (Impatiens walleriana Hook. f. ‘Super Elfin XP White')] was evaluated in three substrates [80:20 peat:perlite, 80:20 peat:WholeTree (a whole pine tree-based substrate), 60:40 peat:WholeTree]. Emissions of CO2, N2O and CH4 were collected over a period of 52 days. Without regard to media, coleus had the highest cumulative CO2 efflux (statistically similar to vinca), due to its increased size in comparison with both vinca and impatiens. Without regard to species, plant-pot systems using the highest proportion of WholeTree (40%) had numerically the most cumulative CO2 efflux (statistically similar to those containing only 20% WholeTree). No differences were observed for the main effect of species or media for N2O or CH4. Results suggest that using a more sustainable high wood fiber substrate in similar proportions to that of perlite in an industry standard mix (20%) could yield similarly sized plants with no negative impact on GHG emissions.Index words: alternative substrate, WholeTree, carbon sequestration, carbon dioxide, nitrous oxide, methane, global climate change.Species used in this study: ‘Redhead' coleus, Solenostemon scutellarioides Thonn. ‘Redhead'; ‘Cooler Grape' vinca, Catharanthus roseus L. ‘Cooler Grape'; ‘Super Elfin XP White' impatiens, Impatiens walleriana Hook. f. ‘Super Elfin XP White'.

Analisis Evapotranspirasi Menggunakan Metode Penman-Monteith pada Vertical Garden

The development of environmentally friendly infrastructure is very important to reduce the environmental damage that has occurred. Environmentally friendly infrastructure can be supported by vertical garden. Plants in vertical garden undergo evaporation process called evapotranspiration process. The evapotranspiration process can be used to find out the needs of water in plants. The method used to obtain the evapotranspiration value is the Penman-Monteith method. The plants used are Plectranthus scutellarioides, Begonia, Coleus, Euodia ridleyi dwarf, Euodia ridleyi, and Chlorophytum comosum. The reference evapotranspiration value in The Hydraulic Laboratory of Sriwijaya University is 4.9826 mm/day and the smallest is 2.1262 mm/day. The reference evapotranspiration value is influenced by temperature, wind speed, and humidity conditions. Based on these three influences, temperature has a greater influence on the reference evapotranspiration. The largest evapotranspiration value of the six types of plants used is the Plectranthus scutellarioides, which is 3.3347 mm/day, the evapotranspiration value of the smallest plant is Euodia ridleyi dwarf, which is 2.6616 mm/day. The location and arrangement of plants and environmental conditions such as temperature, humidity, wind speed affect the amount of evapotranspiration value.

Evaluating the Drought Endurance of Landscaping Ground Cover Plants in a Roof Top Model

Vegetative ground covers are commonly used in urban, tropical roadside gardens. Such landscaping ground covers usually encounter extreme water-deficits and high temperatures from vehicles and urban infrastructures. However, information about the plant species that are appropriate for low maintenance gardens is not available, especially in tropical areas. This study aimed to investigate potential indicators for evaluating plant tolerance to water-deficit situations. A non-irrigated rooftop model was used to test 25 commercial ground cover species in a greenhouse at Mahidol University, Nakhon Pathom Province, Thailand. Each of these 25 species was potted and subjected to one of two conditions: with or without irrigation for 7 days. Physiological responses relevant to plant endurance during water-deficits were monitored, including changes in leaf relative water content (RWC), percent stomatal opening, leaf surface temperature, leaf total chlorophyll content, leaf greenness, maximum quantum yield, and light quantum yield. Moreover, an additional indicator of landscape utility was evaluated, where each species was judged by trained panelists for their esthetic appeal. Diverse responses were observed based on the type of physiological parameter measured, plant species, and duration of drought conditions. Water withdrawal for three days was deemed an appropriate time to determine plant tolerance to water-deficit conditions, as signs of stress were clearly observed in three parameters, i.e., changes in leaf RWC, percent stomatal opening, and esthetic score. Lastly, cluster analysis revealed that seven plant species were appropriate for tropical, urban ground covers, as they had high endurance under water-deficit conditions, namely, Allium schoenoprasum,Liriope muscari, Aloe sp., Sedum x rubrotinctum, Alternanthera ficoidea, Pilea libanensis and Plectranthus scutellarioides.

The Correlation between Structural and Optical Properties of Zinc Hydroxide Nanoparticle in Supports Photocatalytic Performance

- Green synthesized Zn(OH)2 mediated by Coleus blumei Benth leaf for pH: 4, 7, 10 and for calcination temperature: 400 °C, 450 °C, 500 °C, 550 °C, and 600 °C have been characterized by using Fourier transform infra-red (FTIR), ultraviolet–visible (Uv–Vis), and X-ray diffraction (XRD). The bonding formation present Zn– O –H, H– O –H, O –H, and Zn–O indicated Zn(OH)2 nanocrystal successfully synthesized. The optical, dielectric properties, and energy loss function were quantitatively determined from the FTIR spectra by using Kramers-Kronig (KK) dispersion relation. The distance between longitudinal (LO) and transverse (TO) optical phonon vibration mode Δ (LO-TO) and the bandgap increases with increasing the calcination temperature for all pH due to the amount of covalent bond is increase. The best calcination temperature is 600 °C and pH 7 indicated by the rate of the degradation performance is faster than the other temperature and pH. In this study shows FTIR spectra effective ways for determining the optical and dielectric properties, optical phonon vibration mode, and energy loss function of Zn(OH)2 material. • The Zn-O-H, H-O-H, O-H, and Zn-O bonding indicated formed of Zn(OH) 2 nanocrystal. • The n and k , ε 1 and ε 2 (ω), Im ( - 1 / ε 1 ( ω ) ) determined from FTIR spectra by applying K-K relation. • Distance optical phonon vibration (D(LO-TO)) is increases with increasing the calcination temperature for all pH. • The band gap increase with increasing the calcination temperature. • The best calcination temperature for photocatalyst is 600 o C.

Genetic characterization of iler (Plectranthus scutellarioides (L.) R. Br.) based on RAPD molecular marker

Iler (Plectranthus scutellarioides (L.) R. Br.) is an ornamental plant and also used as medicinal plant. The plant is one of medicinal plant for anti hemorrhoids Jamu Saintifik herbal formula in B2P2TOOT Indonesian Ministry of Health. This will lead to commercialization opportunities in herbal drug industry that recently has become increasingly popular. With the emergence of substitution and adulteration of herbal drug and the lack of information on coleus genetic diversity which may result in misidentification, this research was conducted to determine Iler genetic characteristics using RAPD markers. The genomic DNA was extracted from 15 accessions of iler and 3 accessions from genus Plectranthus as an outgroup. Six selected RAPD primers were used in amplification. Dice similarity index was used to calculate similarity index followed by cluster analysis and dendrogram contruction using Unweighted Pair Group Method with Arithmetic Mean (UPGMA). The results showed 52 DNA fragments were produce within the size range 293-2,667 bp and polymorphism level among accessions at 94.23%. Cluster results results in genetic diversity ranging from 40.45-97.87% and a dendogram that shows clustering trend of Iler accessions based on the similarity of morphological characters such as leaf shape and color.

Comparative Genomic Understanding of Gram-Positive Plant Growth-Promoting Leifsonia

Root-associated bacteria play critical roles in shaping plant health for abiotic and biotic stress tolerance. The Leifsonia genus includes pathogenic and beneficial bacteria but limited research is available comparatively across species regarding their association with plants. We recently identified the plant growth-promoting Leifsonia sp. C5G2 isolated from the rhizosphere of Plectranthus scutellarioides (coleus) that increased stress tolerance and quality of water-stressed greenhouse ornamentals. Using this beneficial strain as a model, we performed comparative genomics with beneficial, commensal, and pathogenic Leifsonia spp. to better understand plant association and growth promotion under abiotic stress. Comparative phylogenetic analyses showed that beneficial and commensal Leifsonia spp. clustered separately from pathogenic Leifsonia xyli subsp. xyli. In addition, the beneficial or commensal strains share biosynthetic gene and orthologous protein clusters that are not shared with known phytopathogens in our analysis. The phytopathogenic Leifsonia strains also share noticeably higher percent homology with plant-associated virulence factors in closely related Clavibacter spp. than the beneficial or commensal strains. Genome analysis supplemented with in vitro assays validated the findings that our model growth-promoting Leifsonia sp. strain C5G2 was highly prolific on diverse carbon sources. This is unlike known fastidious growth behaviors of phytopathogenic Leifsonia spp. Beneficial Leifsonia sp. C5G2 imparts water stress tolerance in plants, and multiple genes were identified in the genomes of beneficial Leifsonia strains that are potentially involved in bacterial osmotic stress and the production of osmoprotectants and vitamin B9. This work sheds light on the diversity of the genus Leifsonia, with a better understanding of potential mechanisms employed by poorly understood beneficial bacteria.

Constituents and antibacterial activity of leaf essential oil of Plectranthus scutellarioides

This study covers chemical profiling of leaf essential oil of Plectranthus scutellarioides (L.) R.Br along with the first report on its antibacterial activity. The extraction was performed by microwave assisted hydrodistillation where the yield of essential oil was 0.18%. A total of 28 constituents were separated and identified by gas chromatography mass spectrometry. The constituents that occurred in abundance were spathulenol (24.57%), D-germacrene (14.53%), bicyclogermacrene (11.24%), nonacosane (9.74%) and morillol (4.95%). The antibacterial evaluation of essential oil was carried out against 8 different gram negative and positive strains including multidrug-resistant ones with agar well diffusion method and macrodilution method and was found to be active against all strains. The strongest activity (MIC) was found against multidrug resistant strains of Escherichia coli (0.625 mg/mL) and methicillin resistant Staphylococcus aureus (2.5 mg/mL) that shows the potential of this essential oil.

Constitutive and facultative crassulacean acid metabolism (CAM) in Cuban oregano, Coleus amboinicus (Lamiaceae).

Plants exhibiting the water-conserving crassulacean acid metabolism (CAM) photosynthetic pathway provide some of the most intriguing examples of photosynthetic diversity and plasticity. Here, a largely unnoticed facet of CAM-plant photosynthesis is highlighted: the co-occurrence of ontogenetically controlled constitutive and environmentally controlled facultative CAM in a species. Both forms of CAM are displayed in leaves of Coleus amboinicus Lour. (Lamiaceae), a semi-succulent perennial plant with oregano-like flavour that is native to southern and eastern Africa and naturalised elsewhere in the tropics. Under well-watered conditions, leaves assimilate CO2 predominantly by the C3 pathway. They also display low levels of CO2 uptake at night accompanied by small nocturnal increases in leaf tissue acidity. This indicates the presence of weakly expressed constitutive CAM. CAM expression is strongly enhanced in response to drought stress. The drought-enhanced component of CAM is reversible upon rewatering and thus considered to be facultative. In contrast to C. amboinicus, the thin-leaved closely related Coleus scutellarioides (L.) Benth. exhibits net CO2 fixation solely in the light via the C3 pathway, both under well-watered and drought conditions. However, low levels of nocturnal acidification detected in leaves and stems indicate that the CAM cycle is present. The highly speciose mint family, which contains few known CAM-exhibiting species and is composed predominantly of C3 species, appears to be an excellent group of plants for studying the evolutionary origins of CAM and for determining the position of facultative CAM along the C3-full CAM trajectory.