Acclimation potential of Noni (Morinda citrifolia L.) plant to temperature stress is mediated through photosynthetic electron transport rate.

Noni (Morindacitrifolia L.), a tropical, medicinal plant of the family Rubiaceae utilized since 2000 y ago by the Polynesians, is currently facing a major challenge in production vis-a-vis climate change. The worldwide average temperatures continue to fluctuate, resulting in extremely cold winters and hot summers that reduce plant productivity. Photosynthetic apparatus is an exceptionally sensitive component to estimate the degree of damage at contrasting temperatures. The present study was aimed to evaluate the temperature stress response of Noni plant using the chlorophyll a fluorescence OJIP transients (OJIP transients). Results showed the declined photosynthetic pigment pool and reduced functional and structural integrity of the photosynthetic apparatus under very low- and high-temperature treatments. Drastically lower yield parameters such as φ(Po) and φ(Eo), efficiency ψ(Eo) and performance indices - PIabs and PItotal, and accumulation of inactive reaction centers were observed. Consecutively, a lower level of calculated electron transport from PSII to PSI was observed. In contrast, the enhanced δRo indicates that PSI is more thermo-tolerant as compared to PSII. Additionally, very low and high temperatures cause an increase in antenna size (ABS/RC) and the decrease in the amplitude of I to P phase of fluorescence transient. Overall, the photosynthetic apparatus of leaf tissue was more sensitive to low and high temperatures than the developing fruit. The findings of the present study demonstrated the potential role of thylakoid components of the photosynthetic apparatus, which might be crucial in regulating the temperature stress response in the Noni plant, and thereby crop improvement.

Derived esterase activity in Drosophila sechellia contributes to evolved octanoic acid resistance.

The dietary specialist fruit fly Drosophila sechellia has evolved resistance to the secondary defence compounds produced by the fruit of its host plant, Morinda citrifolia. The primary chemicals that contribute to lethality of M. citrifolia are the medium-chain fatty acids octanoic acid (OA) and hexanoic acid. At least five genomic regions contribute to this adaptation in D. sechellia and whereas the fine-mapped major effect locus for OA resistance on chromosome 3R has been thoroughly analysed, the remaining four genomic regions that contribute to toxin resistance remain uncharacterized. To begin to identify the genetic basis of toxin resistance in this species, we removed the function of well-known detoxification gene families to determine whether they contribute to toxin resistance. Previous work found that evolution of cytochrome P450 enzymatic activity or expression is not responsible for the OA resistance in D. sechellia. Here, we tested the role of the two other major detoxification gene families in resistance to Morinda fruit toxins - glutathione-S-transferases and esterases - through the use of the pesticide synergists diethyl maleate and tribufos that inhibit the function of these gene families. This work suggests that one or more esterase(s) contribute to evolved OA resistance in D. sechellia.

Phytosterols and triterpenes from Morinda lucida Benth. exhibit binding tendency against class I HDAC and HDAC7 isoforms.

The important role of histone deacetylases (HDACs) in the development of cancer has been demonstrated by various studies. Thus targeting HDACs with inhibitors is a major focus in anticancer drug research. Although few synthetic HDAC inhibitors (HDIs) have been approved for cancer treatment, they have significant undesirable side effects. Therefore emphases have been placed on natural HDIs as substitutes for the synthetic ones. In a bid to identify more HDIs, this study evaluated the binding tendency of compounds derived from Morinda lucida Benth. towards selected HDACs for the discovery of potent HDIs as potential candidates for anticancer therapeutics, based on the report of anticancer potentials of Morinda lucida-derived extracts and compounds. Givinostat and 49 Morinda-lucida derived compounds were docked against selected HDAC isoforms using AutodockVina, while binding interactions were viewed with Discovery Studio Visualizer, BIOVIA, 2016. Druglikeness and Absorption-Distribution-Metabolism-Excretion (ADME) parameters of the top 7 compounds were evaluated using the Swiss online ADME web tool. The results revealed that out of the 49 compounds, 3 phytosterols (campesterol, cycloartenol, and stigmasterol) and 2 triterpenes (oleanolic acid and ursolic acid) exhibited high HDAC inhibitory activity compared to givinostat. These 5 compounds also fulfill oral drugability of Lipinski rule of five. Morinda lucida-derived phytosterols and triterpenes show high binding tendency towards the selected HDACs and exhibited good drugability characteristics and are therefore good candidates for further studies in the search for therapies against abnormalities linked with over-activity of HDACs.

Non-additive benefit or cost? Disentangling the indirect effects that occur when plants bearing extrafloral nectaries and honeydew-producing insects share exotic ant mutualists.

BACKGROUND AND AIMS: In complex communities, organisms often form mutualisms with multiple different partners simultaneously. Non-additive effects may emerge among species linked by these positive interactions. Ants commonly participate in mutualisms with both honeydew-producing insects (HPI) and their extrafloral nectary (EFN)-bearing host plants. Consequently, HPI and EFN-bearing plants may experience non-additive benefits or costs when these groups co-occur. The outcomes of these interactions are likely to be influenced by variation in preferences among ants for honeydew vs. nectar. In this study, a test was made for non-additive effects on HPI and EFN-bearing plants resulting from sharing exotic ant guards. Preferences of the dominant exotic ant species for nectar vs. honeydew resources were also examined. METHODS: Ant access, HPI and nectar availability were manipulated on the EFN-bearing shrub, Morinda citrifolia, and ant and HPI abundances, herbivory and plant growth were assessed. Ant-tending behaviours toward HPI across an experimental gradient of nectar availability were also tracked in order to investigate mechanisms underlying ant responses. KEY RESULTS: The dominant ant species, Anoplolepis gracilipes, differed from less invasive ants in response to multiple mutualists, with reductions in plot-wide abundances when nectar was reduced, but no response to HPI reduction. Conversely, at sites where A. gracilipes was absent or rare, abundances of less invasive ants increased when nectar was reduced, but declined when HPI were reduced. Non-additive benefits were found at sites dominated by A. gracilipes, but only for M. citrifolia plants. Responses of HPI at these sites supported predictions of the non-additive cost model. Interestingly, the opposite non-additive patterns emerged at sites dominated by other ants. CONCLUSIONS: It was demonstrated that strong non-additive benefits and costs can both occur when a plant and herbivore share mutualist partners. These findings suggest that broadening the community context of mutualism studies can reveal important non-additive effects and increase understanding of the dynamics of species interactions.

Morinda citrifolia fruit juice prevents ischemic neuronal damage through suppression of the development of post-ischemic glucose intolerance.

Fruit juice of Morinda citrifolia (Noni juice) is a well-known health drink and has various pharmacological properties including antioxidant and anti-inflammatory effects. We have hitherto found the protective effect of Noni juice on brain damage caused by ischemic stress in mice. In addition, we also recently reported that regulation of post-ischemic glucose intolerance might be important for good prognosis. Here, we focused on the effect of Noni juice on the development of the post-ischemic glucose intolerance as a cerebral protective mechanism. Noni juice was obtained from the mature fruit grown in Okinawa (about 1.5 L/4 kg of fruit; 100% ONJ). Male ddY mice were given 10% ONJ in drinking water for 7 days. Then, mice were subjected to 2 h of middle cerebral artery occlusion (MCAO). Ingestion of 10% ONJ suppressed the development of neuronal damage after MCAO. Interestingly, glucose intolerance observed on the 1st day after MCAO completely disappeared after 10% ONJ administration. Furthermore, ONJ treatment significantly increased serum insulin levels much further than the control group on the 1st day, while serum adiponectin levels were not affected at all. These results suggest that ONJ could facilitate insulin secretion after ischemic stress and may attenuate the development of glucose intolerance. These mechanisms may contribute to the neuronal protective effect of ONJ against ischemic stress.

Macroinvertebrate colonization and breakdown of leaves in an astatic pond in south India.

Macroinvertebrate colonization and breakdown of Pongamia pinnata and Morinda tinctoria leaves were studied in an astatic pond in Madura College, Madurai. Morinda tinctoria leaves broke down fasterthan the leaves of P. pinnata. Breakdown capacities of astatic pond cannot be attributed to colonization of macroinvertebrates. Instead, microbial processing, and abiotic fragmentation are suggested as factors controlling breakdown rates. Tanypus sp (midgelarva) was abundant in leaf bags during the experimental period. This midge-larva appeared to use litter accumulations as a microhabitat that provided shelter and a rich supply of food in the form of organic matter Their abundance and regular occurrence of two leaves suggest that midge larvae enhance leaf fragmentation and possibly mediate the incorporation of organic matter in pond sediments once the plant tissue is sufficiently macerated.

Generation of reactive oxygen and antioxidant species by hydrodynamically stressed suspensions of Morinda citrifolia.

The generation of reactive oxygen species (ROS) by plant cell suspension cultures, in response to the imposition of both biotic and abiotic stress, is well-documented. This study investigated the generation of hydrogen peroxide by hydrodynamically stressed cultures of Morinda citrifolia, over a 5-h period post-stress imposition. Suspensions were exposed to repeated passages through a syringe, under laminar flow conditions, corresponding to cumulative energy dissipation levels of approximately 3-6 J kg-1. Extracellular hydrogen peroxide was detected using a luminol-based chemiluminescence assay. The addition of exogenous hydrogen peroxide facilitated the detection of low levels of hydrogen peroxide in the presence of antioxidants. Immediately after shear exposure, there was evidence of significant antioxidative capacity in the sheared cell cultures, which potentially masked any oxidative burst (OB), but which decreased over the following 40 min. This antioxidative capacity was determined to derive from the shearing process. Trials in which ground cellular debris was added to control suspensions suggested that some of the antioxidative capacity observed in stressed suspensions was directly associated with debris generated by the shearing process. Using UV-vis spectrophotometry and HPLC, stress-related increases in the levels of phenolic compounds were detected in suspension filtrates. Under the stress conditions investigated, maximum hydrogen peroxide levels of 11.5 muM were observed, 5 h after shear exposure. This study emphasizes the importance of considering both oxidative and antioxidative capacities as part of a holistic approach to the determination of the OB in hydrodynamically stressed plant cell suspension cultures.

Effects of juice from Morinda citrifolia (Noni) on gastric emptying in male rats.

The effects of juice from Morinda citrifolia (noni) on gastric emptying, gastrointestinal transit, and plasma level of cholecystokinin (CCK) in rats were studied. Male rats were given noni by gavage at levels of 0.25, 1, or 4 ml/kg once per day for one or 7 days. The rats in the control group were given water, while the rats in the experimental group were fasted overnight before measurement of gastrointestinal motility. Gastrointestinal motility was assessed in rats 15 min after intragastric instillation of a test meal containing charcoal (10%) and Na251CrO4 (0.5 microCi/ml). Gastric emptying was determined by measuring the amount of radiolabeled chromium contained in the small intestine as a percentage of the initial amount received. Then, gastrointestinal transit was evaluated by calculating the geometric center of distribution of the radiolabeled marker. Finally, blood samples were collected for measurement of CCK by radioimmunoassay. The administration of noni at 0.25 ml/kg, but not at 1 ml/kg and 4 ml/kg, for 1 day significantly inhibited gastric emptying. In contrast, gastric emptying was significantly inhibited by oral noni (0.25, 1, or 4 ml/kg) for 7 days. Intraperitoneal injection of lorglumide (5 or 10 mg/kg), a selective CCK1 receptor antagonist, effectively attenuated the noni-induced inhibition of gastric emptying. The intestinal transit and body weight, food intake, water intake, urine volume as well as feces weight were not altered by the administration of noni either acutely or chronically, but the administration of oral noni (1 ml/kg) for 7 days increased the level of plasma CCK in male rats. These results suggest that oral noni inhibits gastric emptying in male rats via a mechanism involving stimulation of CCK secretion and CCK1 receptor activation.