Lutein-mediated photoprotection of photosynthetic machinery in Arabidopsis thaliana exposed to chronic low ultraviolet-B radiation.

Ecologically relevant low UV-B is reported to alter reactive oxygen species metabolism and anti-oxidative systems through an up-regulation of enzymes of the phenylpropanoid pathway. However, little is known about low UV-B-induced changes in carotenoid profile and their impacts on light harvesting and photoprotection of photosystem II (PSII) in plants. We investigated carotenoids profile, chlorophyll pigments, phenolics, photosynthetic efficiency and growth in Arabidopsis thaliana (Col-0) plants grown under photosynthetically active radiation (PAR), PAR+ ultraviolet (UV)-A and PAR+UV-A+B regimes for 10 days in order to assess plant acclimation to low UV-B radiation. A chlorophyll fluorescence assay was used to examine UV-B tolerance in plants further exposed to acute high UV-B for 4 and 6 h following a 10-day growth under different PAR and UV regimes. We found that both PAR+ UV-A and PAR+UV-A+B regimes had no negative effect on quantum efficiency, electron transport rate, rosette diameter, relative growth rate and shoot dry weight of plants. Chronic PAR+ UV-A regime considerably (P < 0.05) increased violaxanthin (26 %) and neoxanthin (92 %) content in plants. Plant exposure to chronic PAR+UV-A+B significantly (P < 0.05) increased violaxanthin (48 %), neoxanthin (63 %), lutein (33 %), 9-cis ß-carotene (28 %), total ß-carotene (29 %) and total phenolics (108 %). The maximum photochemical efficiency (Fv/Fm) in leaves was found to be positively correlated with total phenolics (rho = 0.81 and rho = 0.91, P < 0.05 for 4 and 6 h, respectively) and non-photochemical quenching (qN) (rho = 0.81 and rho = 0.84, P < 0.05 for 4 and 6 h, respectively) in plants exposed to acute high UV-B for 4 and 6 h following a 10-day growth under chronic PAR+UV-A+B. There was also a significant positive correlation (rho = 0.93, P < 0.01) between qN and lutein content in the plants exposed to acute high UV-B stress for 4 h following plant exposure to chronic PAR+UV-A+B. The findings from our study indicate that plants grown under chronic PAR+UV-A+B displayed higher photoprotection of PSII against acute high UV-B stress than those grown under PAR and PAR+ UV-A regimes. An induction of phenolics and lutein-mediated development of qN were involved in the photoprotection of PSII against UV-B-induced oxidative stress.

Advancing Bromegrass Breeding Through Imaging Phenotyping and Genomic Selection: A Review.

Breeding forage crops for high yields of digestible biomass along with improved resource-use efficiency and wide adaptation is essential to meet future challenges in forage production imposed by growing demand, declining resources, and changing climate. Bromegrasses (Bromus spp.) are economically important forage species in the temperate regions of world, but genetic gain in forage yield of bromegrass is relatively low. In particular, limited breeding efforts have been made in improving abiotic stress tolerance and resource-use efficiency. We conducted a literature review on bromegrass breeding achievements and challenges, global climate change impacts on bromegrass species, and explored the feasibility of applying high-throughput imaging phenotyping techniques and genomic selection for further advances in forage yield and quality selection. Overall genetic gain in forage yield of bromegrass has been low, but genetic improvement in forage yield of smooth bromegrass (Bromus inermis Leyss) is somewhat higher than that of meadow bromegrass (Bromus riparius Rehm). This low genetic gain in bromegrass yield is due to a few factors such as its genetic complexity, lack of long-term breeding effort, and inadequate plant adaptation to changing climate. Studies examining the impacts of global climate change on bromegrass species show that global warming, heat stress, and drought have negative effects on forage yield. A number of useful physiological traits have been identified for genetic improvement to minimize yield loss. Available reports suggest that high-throughput imaging phenotyping techniques, including visual and infrared thermal imaging, imaging hyperspectral spectroscopy, and imaging chlorophyll fluorescence, are capable of capturing images of morphological, physiological, and biochemical traits related to plant growth, yield, and adaptation to abiotic stresses at different scales of organization. The more complex traits such as photosynthetic radiation-use efficiency, water-use efficiency, and nitrogen-use efficiency can be effectively assessed by utilizing combinations of imaging hyperspectral spectroscopy, infrared thermal imaging, and imaging chlorophyll fluorescence techniques in a breeding program. Genomic selection has been applied in the breeding of forage species and the applications show its potential in high ploidy, outcrossing species like bromegrass to improve the accuracy of parental selection and improve genetic gain. Together, these new technologies hold promise for improved genetic gain and wide adaptation in future bromegrass breeding.

Dengue fever in a rural area of West Bengal, India, 2012: an outbreak investigation.

BACKGROUND: During September 2012, an increased number of fever cases was reported from Ramnagar-II block, Purba Medinipur district. This study investigated the outbreak, with the following objectives: to describe the distribution of fever cases, to determine the risk factors and to recommend preventive measures. MATERIALS AND METHODS: The clinical features, date of onset and outcome of all cases of fever were listed. Blood specimens were collected from affected patients and sent for serological examination. An epidemic curve was plotted and environmental and entomological surveys were carried out. RESULTS: There was a total of 100 cases, of which 56% (56/100) were men.Among the four villages studied, the highest number of cases was from Gopalpur 37% (37/100), followed by Badalpur 26% (26/100); 19% (19/100) of cases had a history of migration from dengue-endemic areas. The majority of cases were in age group 15-45 years - 52% (52/100), followed by the age group >45 years - 28% (28/100). All the cases had history of fever (100%), followed by myalgia - 82%, headache - 78%, and retro-orbital pain - 73%. The outbreak started on 7 September 2012, peaked on 18 September, then gradually declined and no further cases were noted after 28 September 2012. Seventy-nine percent (79/100) of cases were NS1 test positive (non-structural antigen-1) and 72% (13/18) cases were positive on a dengue monoclonal antibody (IgM) capture enzyme-linked immunosorbent assay (MAC-ELISA) test. All recovered except one (case-fatality ratio: 1%). The values for Household Index, Container lndex and Breteau Index of the four villages were: Badalpur, 3%, 10% and 5%; Gopalpur, 13%, 23% and 18%; Ramchandrapur, 9%, 11%, and 13%; and Tajpur, 2%, 2% and 2%. CONCLUSION: The outbreak was probably due to dengue fever. The study led to a recommendation to destroy water containers and use mosquito nets. The outbreak was controlled.

An outbreak of pandemic influenza A (H1N1) in Kolkata, West Bengal, India, 2010.

BACKGROUND & OBJECTIVES: An increased number of cases with influenza like illness (ILI) were reported in Greater Kolkata Metropolitan Area (GKMA) during July and August 2010. We investigated these cases to confirm the outbreak, describe the distribution of patients and propose control measures. METHODS: A suspected case of influenza like illness (ILI) was defined as acute onset of fever (>38°C) with cough or sore throat and a confirmed case as ILI case with throat swab positive for influenza A (H1N1) on RT-PCR. The demographic and clinical details were collected from patients attending the swine flu OPD of Infectious Disease Hospital, Kolkata, during July 5 to August 16, 2010. RESULTS: Overall 440 patients with ILI attended the swine flu OPD of Infectious Disease and Bengal General hospital during the study period, of which 129 were positive for influenza A (H1N1). Four patients died (case fatality ratio: 0.90%). Besides fever, common symptoms included cough (73%), running nose (54%), sore throat (43%), respiratory distress (25%) and diarrhoea (4%). Forty seven (11%) patients (including the four who died) had co-morbidities. The outbreak started on July 10, peaked on July 24 and subsided by August 14, 2010. A total of 372 (85%) patients were from GKMA. Majority (n=168, 45%) of the cases from GKMA were from 6 boroughs of Kolkata Municipal Areas. INTERPRETATION & CONCLUSIONS: An outbreak of influenza A (H1N1) occurred in Kolkata predominantly affecting young and middle aged population. State health authorities implemented several interventions to limit the outbreak including training of health care providers in case management and infection control, vaccination of health care workers, creation of isolation wards and administration of oseltamivir to ILI patients, and community health education about social distance and personal hygiene measures.

2,4,6-Trichlorophenol mediated increases in extracellular peroxidase activity in three species of Lemnaceae.

Chlorinated phenols, or chlorophenols, are persistent priority pollutants that are widespread in the environment. Class III peroxidases are well-characterised plant enzymes that can catalyse the oxidative dechlorination of chlorophenols. Expression of these enzymes by plants is commonly associated with plant stress, therefore limiting scope for phytoremediation. In this study, we have quantitatively compared peroxidase activity and phytotoxicity as a function of 2,4,6-trichlorophenol (TCP) concentration in three species of Lemnaceae; Lemna minor, Lemna gibba and Landoltia punctata. Effects of TCP on the growth rates of the three species differed considerably with L. punctata being the most tolerant species. TCP also affected photosynthetic parameters, causing a decrease in open photosystem II reaction centres (qP) and, in L. punctata only, a decrease in non-photochemical quenching (qN). In parallel, TCP exposure resulted in increased peroxidase activity in all three species. Peroxidase activity in L. minor and L. gibba displayed an inverse relationship with biomass accumulation, i.e. the more growth reduction the more peroxidase activity. In contrast, induction of peroxidase activity in L. punctata was bi-phasic, with a TCP-induced activity peak at concentrations that had no major effect on growth, and further induction under phytotoxic concentrations. The mechanism by which L. punctata recognises and responds to low concentrations of an anthropogenic compound, in the absence of wide-ranging stress, remains enigmatic. However, we conclude that this "window" of peroxidase production in the absence of major growth inhibition offers potential for the development of sustainable, peroxidise-mediated phytoremediation systems.

Photosynthetic responses to chromosome doubling in relation to leaf anatomy in Lonicera japonica subjected to water stress.

Gas exchange, chlorophyll fluorescence, and contents of some metabolites in two Japanese honeysuckle (Lonicera japonica Thunb.) cultivars, Damaohua (2n = 2x) and Jiufengyihao (2n = 4x), were compared with explore the function of chromosome doubling under water stress conditions. Water stress significantly decreased net photosynthesis rate, stomatal conductance, and transpiration rate of both cultivars. It also decreased electron transport rate, effective quantum yield of Photosystem II, photochemical quenching, and starch content, but increased non-photochemical quenching and contents of total soluble sugars, proline, and malondialdehyde. However, the tetraploid cultivar showed higher resistance to water stress than the diploid, as indicated by the fact that gas exchange, chlorophyll fluorescence, and metabolites were less affected for the tetraploid than the diploid. Moreover, the tetraploid recovered more quickly than the diploid after re-watering. Morphological and anatomical analysis further revealed that the tetraploid possessed less whole plant leaf area, higher leaf mass per unit area, thicker epidermis (both upper and lower) and palisade tissue, as well as denser pubescence. All of those specialised structures caused by chromosome doubling might lead to greater capacity in coping with drought stress. Our findings suggest that the effect of chromosome doubling on drought resistance in L. japonica could attribute to the improvement of structure and photosynthesis-related traits.