Dependence of growth inhibiting action of increased planting density on capacity of lettuce plants to synthesize ABA.
J Plant Physiol. 2017 Nov 11;220:69-73
Authors: Vysotskaya LB, Arkhipova TN, Kudoyarova GR, Veselov SY
Inhibition of lettuce plant growth under increased planting density was accompanied by accumulation of abscisic acid (ABA) in the shoots of competing plants. To check causal relationship between these responses we studied the effect of decreased synthesis of ABA on growth indexes and hormonal balance of lettuce plants under elevated density of their planting (one (single) or three (competing) plants per pot). Herbicide fluridone was used to inhibit ABA synthesis. Preliminary experiments with single plants showed that presence of fluridone in the soil solution at rather low concentration (0.001mg/L) did not affect either chlorophyll content or growth rate of shoots and roots during at least one week. Treatment of competing (grouped) plants with this concentration of fluridone prevented both accumulation of ABA and competition induced growth inhibition. These results confirm important role of this hormone in the growth inhibiting effect of increased planting density. Furthermore, as in the case of ABA, fluridone prevented allocation of indoleacetic acid (IAA) to the shoots of competing plants likely contributing to leveling off the increase in the ratio of leaf area to their mass that is characteristic effect of shading in the dense plant populations. The results suggest involvement of ABA in allocation of IAA in competing plants. Application of fluridone did not influence the concentration of cytokinins in the shoots, whose level was decreased by competition either in fluridone treated or control (untreated with fluridone) plants. Accumulation of ABA in the shoots of competing plants accompanied by inhibition of their growth and the absence of either accumulation of ABA or inhibition of their growth in fluridone treated grouped plants confirms importance of ABA synthesis for growth response to competition.
PMID: 29149646 [PubMed - as supplied by publisher]
Exploration for the Salinity Tolerance-Related Genes from Xero-Halophyte Atriplex canescens Exploiting Yeast Functional Screening System.
Int J Mol Sci. 2017 Nov 17;18(11):
Authors: Yu G, Li J, Sun X, Liu Y, Wang X, Zhang H, Pan H
Plant productivity is limited by salinity stress, both in natural and agricultural systems. Identification of salt stress-related genes from halophyte can provide insights into mechanisms of salt stress tolerance in plants. Atriplex canescens is a xero-halophyte that exhibits optimum growth in the presence of 400 mM NaCl. A cDNA library derived from highly salt-treated A. canescens plants was constructed based on a yeast expression system. A total of 53 transgenic yeast clones expressing enhanced salt tolerance were selected from 10⁵ transformants. Their plasmids were sequenced and the gene characteristics were annotated using a BLASTX search. Retransformation of yeast cells with the selected plasmids conferred salt tolerance to the resulting transformants. The expression patterns of 28 of these stress-related genes were further investigated in A. canescens leaves by quantitative reverse transcription-PCR. In this study, we provided a rapid and robust assay system for large-scale screening of genes for varied abiotic stress tolerance with high efficiency in A. canescens.
PMID: 29149055 [PubMed - in process]
Farmers' perspective on herbicide resistant weeds and application of resistance management strategies: results from a German survey.
Pest Manag Sci. 2017 Nov 17;:
Authors: Ulber L, Rissel D
BACKGROUND: A herbicide resistance survey was conducted in Germany to determine farmers' awareness of herbicide resistance and experience with resistant weeds, the used information sources on herbicide resistance and methods employed to confirm resistance. In addition, the application pattern and perception of resistance management strategies by farmers were assessed.
RESULTS: The majority of farmers (88%) was aware of the presence of herbicide resistance cases in Germany and 64% and 50% of farmers reported that resistant weeds were detected in their county or on their farm, respectively. Resistance management strategies were reported to be applied by 87% of the farmers and three clusters of different resistance management approaches used to minimize the evolution of resistant weed populations were identified and linked to farmers' perception of resistance and farm-management characteristics. When asked about obstacles to adopting resistance management strategies, higher cost was the obstacle most cited by farmers followed by weather and labour intensity/labour costs.
CONCLUSION: Outcomes from this survey may help researchers and crop consultants to increase understanding of farmers' perception of herbicide resistance issues, to improve knowledge dissemination concerning herbicide resistance and to develop resistance management programs with high agronomic practicability and acceptance by farmers.
PMID: 29148615 [PubMed - as supplied by publisher]
Effects of bergenin on methylglyoxal-induced damage in osteoblastic MC3T3-E1 cells.
J Appl Toxicol. 2017 Nov 17;:
Authors: Lee KH, Choi EM
Bergenin is the main chemical constituent of plants in the genus Bergenia, which are used in traditional medicines. Methylglyoxal (MG), a highly reactive dicarbonyl compound, is the major precursor for forming advanced glycation end products (AGEs). Pretreating MC3T3-E1 cells with bergenin prevented MG-induced protein adduct formation. Bergenin inhibited the MG-induced soluble receptor for AGE (sRAGE), interleukin, reactive oxygen species and mitochondrial superoxide production. Additionally bergenin increased glyoxalase I activity, glutathione, heme oxygenase-1 and nuclear factor erythroid 2-related factor 2 levels in the presence of MG. Pretreatment with bergenin before MG exposure reduced MG-induced mitochondrial dysfunction by preventing mitochondrial membrane potential dissipation, loss of adenosine triphosphate and reduced adenosine monophosphate-activated protein kinase. These results demonstrate that bergenin may prevent the development of diabetic osteopathy.
PMID: 29148590 [PubMed - as supplied by publisher]
Klebsiella sp. confers enhanced tolerance to salinity and plant growth promotion in oat seedlings (Avena sativa).
Microbiol Res. 2018 Jan;206:25-32
Authors: Sapre S, Gontia-Mishra I, Tiwari S
Plant growth and yield is adversely affected by soil salinity. Salt tolerant plant growth-promoting rhizobacteria (PGPR) strain IG 3 was isolated from rhizosphere of wheat plants. The isolate IG 3 was able to grow in presence of NaCl ranging from 0 to 20% in Luria Bertani medium. The present study was planned to evaluate the role of inoculation of PGPR strain IG 3 and its efficacy in augmenting salt tolerance in oat (Avena sativa) under NaCl stress (100mM). The physiological parameter such as shoot length, root length, shoot dry weight, root dry weight and relative water content (RWC) were remarkably higher in IG 3 inoculated plants in comparison to un-inoculated plants under NaCl stress. Similarly, the biochemical parameters such as proline content, electrolyte leakage and malondialdehyde (MDA) content and activities of antioxidant enzymes were analyzed and found to be notably lesser in IG 3 inoculated oat plants in contrast to un-inoculated plants under salt stress. Inoculation of IG 3 strain to oat seedlings under salt stress positively modulated the expression profile of rbcL and WRKY1 genes. Root colonization of root surface and interior was demonstrated using scanning electron microscopy and tetrazolium staining, respectively. Due these outcomes, it could be implicated that inoculation of PGPR strain IG 3 enhanced plant growth under salt stress condition. This study demonstrates that PGPR play an imperative function in stimulating salt tolerance in plants and can be used as biofertilizer to enhance growth of crops in saline areas.
PMID: 29146257 [PubMed - in process]
Phosphatidylcholine absence affects the secretion of lipodepsipeptide phytoxins in Pseudomonas syringae pv. syringae van Hall CFCC 1336.
Microbiol Res. 2018 Jan;206:113-120
Authors: Cao F, Xiong M, Li S, Cai H, Sun Y, Yang S, Liu X, Zhu R, Yu X, Wang X
Pseudomonas syringae pv. syringae van Hall CFCC 1336 (Pss 1336) is the causal agent of bacterial disease of stone fruit trees, and also able to elicit hypersensitive response (HR) in non-host tobacco. It is known that this pathogen uses PCS-pathway to synthesize phosphatidylcholine (PC), and mutation of the pcs gene abolishes bacterial PC synthesis. Previous study also found that the 1336 pcs(-) mutant lacking PC in its membrane phospholipids was unable to secrete HrpZ harpin and elicit HR in non-host plants. In this study, we further analyzed virulence of lipodepsipeptide phytoxins of Pss 1336 wild type (pcs(+)), the 1336RM (pcs-/+) and the 1336 pcs- mutant, and found that the 1336 pcs- mutant was unable to cause necrosis of Chinese date fruits and inhibit fungal growth. HPLC analysis also showed that the 1336 pcs- mutant markedly reduced its secretion of lipodepsipeptide phytoxins. Analysis of semi-quantitative RT-PCR revealed that PC presence or absence did not affect gene expressions of SyrD, PseABC and PseEF efflux systems at transcriptional level. However, western blotting assays found that PseE and PseF present only in the cytoplasmic fractions but undetectable in the membrane extract of the 1336 pcs- mutant. PC absence obviously interrupted the translocation of two membrane-associated proteins PseE and PseF from cytoplasm to cell membranes to form an intact PseEF efflux system in bacterial membranes. Failure to form PseEF efflux system could be a major factor for less lipopeptide-phytoxin secretion. Our results demonstrate that PC in bacterial membrane phospholipids plays an important role in maintaining physiological functions of PseEF efflux system.
PMID: 29146248 [PubMed - in process]
Spread of multidrug-resistant Escherichia coli harboring integron via swine farm waste water treatment plant.
Ecotoxicol Environ Saf. 2017 Nov 13;149:36-42
Authors: Park JH, Kim YJ, Binn-Kim, Seo KH
Wastewater treatment plants (WWTPs) that release treated wastewater into the environment have emerged as a major threat to public health. In this study, we investigated Escherichia coli load and antibiotic-resistance profiles across different treatment processes at a swine farm WWTP. The frequency of the detection of class 1 and 2 integrons, and their association with antibiotic resistance, were also analyzed. Samples were obtained at each of five sampling sites that represented each processing step within the WWTP. The largest decrease in E. coli load was observed during the anaerobic digestion step (from 4.86 to 2.89log CFU/mL). Isolates resistant to β-lactam antibiotics were efficiently removed after a series of treatment steps, whereas the proportions of isolates resistant to non-β-lactam antibiotics and multidrug-resistant strains were maintained across treatments. The occurrence of integron-positive strains was not significantly different at the various sampling sites (43.4-70%; p>0.05). Of the class 1 integron-positive isolates, 17.9% harbored the integron-associated gene cassettes aadA2, aadA12, aadA22, and dfrA15. To the best of our knowledge, this is the first description of a class 1 integron containing the aadA12 gene cassette from a swine farm and the presence of a class 1 integron containing dfrA15 in E. coli. This suggests that novel antibiotic-resistance gene cassette arrays could be generated in swine farm WWTPs. Moreover, 75% of integron-positive strains were categorized as multidrug resistant, whereas only 15.4% of integron-negative strains were multidrug resistant (p<0.05), indicating that integrons may be responsible for mediating resistance in WWTPs. With regard to the occurrence of multidrug-resistant, integron-positive E. coli recovered from the final effluent, our results highlighted the potential risks associated with wastewater discharge from swine farm WWTPs in terms of the spread of antibiotic-resistant bacteria to the aquatic environment.
PMID: 29145163 [PubMed - as supplied by publisher]