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Plants in the genus Melaleuca have been widely used as traditional medicine mainly because of their broad spectrum antimicrobial activity. In this study, we reported the complete chloroplast genome of Melaleuca cajuputi subsp. cumingiana. The chloroplast genome of this species is 158,855 bp in length, including a pair of inverted repeat regions (IRs) (26,727 bp) that is divided by a large single-copy (LSC) area (87,338 bp) and a small single-copy (SSC) area (18,063 bp). The circular chloroplast genome of M. cajuputi subsp. cumingiana contains 135 unique genes, composing of 87 protein-coding genes, 40 tRNA genes, and eight rRNA genes. Phylogenetic analysis indicates that M. cajuputi subsp. cumingiana was clustered with species in the tribe Melaleuceae. This complete chloroplast genome of M. cajuputi subsp. cumingiana will provide a powerful tool to accelerate breeding, biotechnological and phylogenetic study.

A new chromone, 5,7-dihydroxy-2 -(hydroxymethyl)-6,8-dimethyl-chromen-4-one, named melachromone, together with 12 known compounds, including chromones, anthraquinone, flavonoids, flavonoid glycosides, benzene derivatives, ellagic acids and terpenes, were isolated from the leaves of Melaleuca cajuputi Powell. Their structures were characterised by spectroscopic methods.

Extracts of Melaleuca cajuputi were obtained by supercritical (carbon dioxide) extraction and solvent (hexane) extraction methods. This work is aimed at adapting the green technology of using supercritical CO2 (SC-CO2) as solvent in a batch process to extract Melaleuca cajuputi leaves. The plant leaves were collected from Trengganu, Malaysia. Cajuputi extract analyses were performed by GC and GC/MS. The maximum yields obtained were 4.2% and 6.0%, respectively, by supercritical fluid (SFE) and solvent extraction (SE). Several compounds were identified and significant qualitative and quantitative differences were observed under different conditions. The major components of Cajuputi oil consisted of sesquiterpenes (δ-elemene, β-elemene, β-caryophyllene, α-humulene, 9-epi-β-caryophyllene), their oxygenated derivatives (viridiflorol, platyphyllol, β-eudesmol, bulnesol, (Z,Z)-farnesol and (E,E)-farnesal) and polyphenolic ketones (isoeugenitine and three unknown compounds).

SummaryThe submerged Melaleuca forests have an important role in the regulation of climate and the protection of wildlife and the environment in southern Vietnam. This paper studies the pollination ecology of the Asian giant honey bee (Apis dorsata), the Asian dwarf honey bee (Apis florea) and other pollinators on the two prominent plants (Melaleuca cajuputi and Nypa fruticans) in the forests. The results show that the nectar of Melaleuca flowers was secreted in the largest volume with the lowest sugar content in the early morning. Then, due to evaporation, the volume dropped to the lowest with the highest sugar content in the early afternoon. The sugar value present in Melaleuca flowers was the highest (466 Mg of sugar per flower) at 10.00 h in the morning. Nypa flowers opened early in the morning, their pollen release increased gradually, reached a peak at 09.00 h and finished at sunset. The study of pollinators on the Melaleuca and Nypa flowers showed the three following forms of partitioning in the Me...

Distribution of aluminum (Al) within plant components and Al-induced changes in cell wall polysaccharides in root tips of Eucalyptus camaldulensis Dehnh. seedlings were compared with those of Melaleuca cajuputi Powell. In E. camaldulensis, 0.5 mM Al (pH 4.2 for 40 d) reduced plant dry weight by 50%, increased callose concentration in the root tips and induced leaf necrosis. In comparison with M. cajuputi, Al concentrations were higher in roots and leaves of E. camaldulensis on both a fresh weight basis and in the cell sap, but were lower in the cell wall. Al increased pectin, hemicellulose and cellulose concentration in the cell walls of E. camaldulensis root tips. Al-induced leaf necrosis and growth reduction in E. camaldulensis is discussed in the context of potentially toxic concentrations of Al in plant tissue and changes in polysaccharide content which could reduce water and nutrient uptake and cell wall extensibility in roots.

We exposed the roots of nine Myrtaceae species (Melaleuca bracteata F. Muell., Melaleuca cajuputi Powell, Melaleuca glomerata F. Muell., Melaleuca leucadendra [L.] L., Melaleuca quinquenervia [Cav.] S.T. Blake, Melaleuca viridiflora Sol. ex Gaertner, Eucalyptus camaldulensis Dehnh., Eucalyptus deglupta Bl., and Eucalyptus grandis W. Hill ex Maiden) to 1 mM Al in a nutrient solution for either 24 h or 20 days to evaluate their sensitivity to excess Al and to determine whether callose and lignin formation can be used as interspecific indicators of Al sensitivity. Inhibition of root elongation by Al varied among the species. Melaleuca leucadendra, M. cajuputi, E. grandis, M. quinquenervia, and E. deglupta were tolerant to 1 mM Al, whereas M. viridiflora, E. camaldulensis, M. glomerata, and M. bracteata were sensitive to 1 mM Al. We found that Al induced callose formation in the root tips of each species, but lignin was formed only in the root tips of the most sensitive species, M. bracteata. Root elongation at 1 mM Al was negatively correlated with Al-induced callose formation but not with the Al-induced lignin formation in the root tips. These results suggest that Al-induced callose formation, rather than lignin formation, can be used as an interspecific indicator of Al sensitivity.

The embankment band or raised bed is commonly used in the Mekong Delta for the cultivation of crops such as yam, cassava, and watermelon as well as perennial crops. The method aims to avoid wet season inundation of the plants while providing water in side-ditches for irrigation during the dry season. The effects of this practice upon plant growth have not been well documented. Therefore, the beneficial effects of embankment on biomass production and plant nutrient status were examined using Melaleuca cajuputi Powell. Embankment bands 0.4 m high with 0.8 m deep side-ditches were constructed on acid sulphate soils in the Mekong Delta in 1998. Seedlings of M. cajuputi were planted on the embankment bands and on the adjacent natural ground surface (i.e. no embankment) as a control. One year after planting, biomass production and mineral nutrition status in various plant parts of M. cajuputi were determined. Planting on embankment bands enhanced plant growth in terms of plant height, number of leaves,...

Staphylococcus aureus cells were exposed to increasing concentrations of Australian tea tree oil, cajuput oil, niaouli oil, Lema oil, kanuka oil and manuka oil as well as of a β-triketone complex isolated from manuka oil. The death kinetics were determined by calculation of log10 reduction factors after increasing exposure periods. Niaouli oil turned out to be highly active, followed by Lema (this is a registered trademark), tea tree and cajuput oils. Kill rate data indicated that 1.0% (v/v) were lethal to stationary phase cells in the assay conditions used. At 2.0% (v/v), niaouli oil and Lema oil yielded a complete 6.8 log10 reduction of cell numbers in suspensions within 60 min, whereas cells treated with tea tree and cajuput oils were inactivated more slowly within 120 min and 240 min, respectively. Kanuka oil and manuka oil as well as the β-triketone complex, the active principle of manuka oil, lacked any bactericidal properties. Their high effectiveness against Gram-positive bacteria can be ...

The effects of N-source and Al on the growth of seedlings of Melastoma malabathricum, Acacia mangium, and Melaleuca cajuputi, which are tropical woody plants and are very tolerant to Al, and barley (Hordeum vulgare), which is a typical Al-sensitive plant, were investigated. The Al and N treatments consisted of the application of either 0 or 0.5 mM Al, and 2 mM NH4 + or N03 -, respectively. Growth of the tropical plants was enhanced by Al and NH4 application. In all the plant species, the pH of the culture solution decreased and the concentrations of soluble Al and P increased with the + NH4 treatment, which positively affected the growth of the tropical plant species. Excised roots of M. malabathricum dissolved insoluble Al with NH4 application and absorbed Al mainly from root tips. Al did not affect the leaf N concentration except in the case of barley. Roots of M. cajuputi exuded a large amount of citrate, which slightly increased by the + Al treatment. In A. mangium, the reactivity of soluble ...

Plants in which growth was reduced by low and high Al applications were designated as Al-sensitive plant (Hordeum vulgare) and Al-medium tolerant plants (Leucaena leucocephala, Ischaemum barbatum, Stylosanthes guianensis, and Fagopyrum esculentum), respectively, while plants in which growth was not affected or was stimulated by Al application were designated as Al-tolerant plant (Brachiaria ruziziensis) and Al-stimulated plants (Melastoma malabathricum, Melaleuca cajuputi, Acacia mangium, Hydrangea macrophyila, Vaccinium macrocarpon, Polygonum sachalinense, and Oryza sativa), respectively. Plants tolerant to or stimulated by Al were further classified based on the criteria of Al accumulation: 1) Al-excluders such as M. cajuputi, A. mangium, L. leucocephala, I. barbatum, S. guianensis, and O. sativa, 2) Al root-accumulators such as V. macrocarpon, B. ruziziensis, and P. sachalinense, and 3) Al-accumulators such as M. malabathricum, H. macrophylla, and F. esculentum. The growth and N, P, and K upta...

Reference strains of Staphylococcus aureus ATCC 9144 (NCTC 6571), Escherichia coli ATCC 10536 (NCTC 10418) and Pseudomonas aeruginosa ATCC 25668 (NCTC 10662) as well as bacteria isolated from patient's clinical material were tested for their resistance to different cajuput oil fractions. The antimicrobial effect of (−)-linalool, (−)-terpinen-4-ol, (±)-α-terpineol and 1,8-cineole as isolated constituents of cajuput oil have been demonstrated.

The negative charge on the plasma membrane (PM) is mainly derived from the phosphate group of phospholipids. One of the mechanisms of aluminum (Al) toxicity is to increase the PM permeability of root cells by binding to the negative sites on the PM. Thus, PM with a higher proportion of phospholipids could be more susceptible to Al toxicity. In our previous study, we showed that tolerance to Al and low-calcium in rice was enhanced by decreasing the proportion of phospholipids in root cells. Both Melastoma malabathricum L. and Melaleuca cajuputi Powell are dominant woody species that grow in tropical acid sulfate soils, and have been reported to be more tolerant to Al than rice. Surprisingly, the proportion of PM phospholipids in root cells of M. malabathricum and M. cajuputi was considerably low. Our present findings suggest that PM lipid composition plays an important role in Al tolerance mechanisms in various plant species.