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91.
Krishna Kumar Natarajan Amaresan Someshwar Bhagat Kutthum Madhuri Palaniswamy Udhayaraj Ramesh Chandra Srivastava 《Archives Of Phytopathology And Plant Protection》2013,46(14):1399-1409
In this study, the in vitro potential of 42 Trichoderma spp. were evaluated against four isolates of soil borne phytopathogenic fungi viz., Rhizoctonia solani, Macrophomina sp., Sclerotium rolfsii and Pythium aphanidermatum in dual culture techniques and through production of volatile and non-volatile inhibitors. In vitro screening results showed that the proportion of isolates with antagonistic activities was highest for the S. rolfsii followed by R. solani, Macrophomina sp. and P. aphanidermatum, respectively. The isolates TNT1, TNP2 and TWP1 showed consistent results in volatile and non-volatile activity in vitro against any of the two pathogens tested. Based on genomic finger prints, potential isolates showed no particular correlation between the origin of the isolates and the Random Amplified Polymorphic DNA (RAPD) groups could not be established. However, the polymorphism shown by the isolates did not correlate to their level of antagonism. Whereas, in physiology studies using BIOLOG (microbial identification system), three groups were formed, one group consists with 14 different Trichoderma species and two groups with two isolates each comprised of only T. koningii and T. viride. 相似文献
92.
K. Nithya Khalid A.I.M. Bukhari V. Valluvaparidasan M. Rajakumar K. Karunanithi A. Ramesh Sundar 《Archives Of Phytopathology And Plant Protection》2013,46(16):1997-2007
Red rot, caused by Colletotrichum falcatum Went, is one of the most important diseases of sugarcane (Saccharum officinarum L.). The pathogen shows a great diversity in virulence as a number of pathotypes are known to occur in nature. In the present study, the toxin producing ability and genetic variability among isolates of C. falcatum collected from major sugarcane growing areas of Tamil Nadu, India were analysed. The C. falcatum isolates differed significantly in their ability to produce toxin in vitro. The toxin from C. falcatum isolate Cf 671a induced the maximum electrolyte leakage (300 μS) from sugarcane leaf tissues. The genetic relatedness of the isolates of C. falcatum differing in toxin production potential was investigated by using RAPD analysis. Analysis of the genetic coefficient matrix derived from the scores of RAPD profiles showed that minimum and maximum percent similarities among the tested C. falcatum isolates were in the range of 19 to 95% respectively. The phylogenetic analysis by the UPGMA identified two main clusters. Cluster A contains only one isolate (Cf 98061) and all the other isolates were placed in Cluster B confirming high genetic diversity among the isolates. No correlation was observed between clustering of the C. falcatum isolates in the dendrogram and their toxin producing abilities. 相似文献
93.
Meena Shekhar Ramesh C. Sharma Rathore Singh 《Archives Of Phytopathology And Plant Protection》2013,46(3):259-263
The post-flowering stalk rots (PFSR) are a complex disease, which are widely distributed in almost all the maize growing regions across the globe. A number of fungi are involved in causing decay of the pith resulting in pre-mature wilting of the plants. Most of the commercially grown cultivars have shown a high level of disease incidence at the grain filling stage. A systematic breeding programme on PFSR was initiated in India in collaboration with Asian Regional Maize Program of CIMMYT. Under this programme, germplasm screening was carried out at four ‘hot spot’ locations in India for different diseases: Hyderabad (Cephalosporium maydis), Udaipur (Fusarium moniliforme), Ludhiana and Delhi (Macrophomina phaseolina). Across the locations, promising maize genotypes were artificially inoculated using the toothpick method, year after year; resistant plants were selfed to derive resistant inbreds. After extensive screening, three resistant lines, namely PFSR-13-5, JCY2-2-4-1-1-1-1 and JCY3-7-1-2-1-b-1, were identified. In addition, the resistance level of five pools/populations; (PFSR (Y)-C1, PFSR (white), Extra-early (White), P-100, P-300 and P-345) was upgraded to an acceptable level. These genotypes may prove useful for utilisation in breeding cultivars for resistance to PFSR. 相似文献
94.
95.
Morten Lillemo Arun K. Joshi Ravindra Prasad Ramesh Chand Ravi P. Singh 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2013,126(3):711-719
Spot blotch caused by Bipolaris sorokiniana is a major disease of wheat in warm and humid wheat growing regions of the world including south Asian countries such as India, Nepal and Bangladesh. The CIMMYT bread wheat line Saar which carries the leaf tip necrosis (LTN)-associated rust resistance genes Lr34 and Lr46 has exhibited a low level of spot blotch disease in field trials conducted in Asia and South America. One hundred and fourteen recombinant inbred lines (RILs) of Avocet (Susceptible) × Saar, were evaluated along with parents in two dates of sowing in India for 3 years (2007–2008 to 2009–2010) to identify quantitative trait loci (QTL) associated with spot blotch resistance, and to determine the potential association of Lr34 and Lr46 with resistance to this disease. Lr34 was found to constitute the main locus for spot blotch resistance, and explained as much as 55 % of the phenotypic variation in the mean disease data across the six environments. Based on the large effect, the spot blotch resistance at this locus has been given the gene designation Sb1. Two further, minor QTL were detected in the sub-population of RILs not containing Lr34. The first of these was located about 40 cM distal to Lr34 on 7DS, and the other corresponded to Lr46 on 1BL. A major implication for wheat breeding is that Lr34 and Lr46, which are widely used in wheat breeding to improve resistance to rust diseases and powdery mildew, also have a beneficial effect on spot blotch. 相似文献
96.
An extracellular low temperature-active alkaline stable peptidase from Acinetobacter sp. MN 12 was purified to homogeneity with a purification fold of 9.8. The enzyme exhibited specific activity of 6,540 U/mg protein, with an apparent molecular weight of 35 kDa. The purified enzyme was active over broad range of temperature from 4 to 60 °C with optimum activity at 40 °C. The enzyme retained more than 75 % of activity over a broad range of pH (7.0–11.0) with optimum activity at pH 9.0. The purified peptidase was strongly inhibited by phenylmethylsulfonyl fluoride, giving an indication of serine type. The K m and V max for casein and gelatin were 0.3529, 2.03 mg/ml and 294.11, 384.61 μg/ml/min respectively. The peptidase was compatible with surfactants, oxidizing agents and commercial detergents, and effectively removed dried blood stains on cotton fabrics at low temperature ranging from 15 to 35 °C. 相似文献
97.
Ramesh Prasad Pandey Sailesh Malla Dinesh Simkhada Byung-Gee Kim Jae Kyung Sohng 《Applied microbiology and biotechnology》2013,97(5):1889-1901
Quercetin, a flavonol aglycone, is one of the most abundant flavonoids with high medicinal value. The bioavailability and pharmacokinetic properties of quercetin are influenced by the type of sugars attached to the molecule. To efficiently diversify the therapeutic uses of quercetin, Escherichia coli was harnessed as a production factory by the installation of various plant and bacterial UDP-xylose sugar biosynthetic genes. The genes encoding for the UDP-xylose pathway enzymes phosphoglucomutase (nfa44530), glucose-1-phosphate uridylyltransferase (galU), UDP-glucose dehydrogenase (calS8), and UDP-glucuronic acid decarboxylase (calS9) were overexpressed in E. coli BL21 (DE3) along with a glycosyltransferase (arGt-3) from Arabidopsis thaliana. Furthermore, E. coli BL21(DE3)/?pgi, E. coli BL21(DE3)/?zwf, E. coli BL21(DE3)/?pgi?zwf, and E. coli BL21(DE3)/?pgi?zwf?ushA mutants carrying the aforementioned UDP-xylose sugar biosynthetic genes and glycosyltransferase and the galU-integrated E. coli BL21(DE3)/?pgi host harboring only calS8, calS9, and arGt-3 were constructed to enhance whole-cell bioconversion of exogeneously supplied quercetin into 3-O-xylosyl quercetin. Here, we report the highest production of 3-O-xylosyl quercetin with E. coli BL21 (DE3)/?pgi?zwf?ushA carrying UDP-xylose sugar biosynthetic genes and glycosyltransferase. The maximum concentration of 3-O-xylosyl quercetin achieved was 23.78 mg/L (54.75 μM), representing 54.75 % bioconversion, which was an ~4.8-fold higher bioconversion than that shown by E. coli BL21 (DE3) with the same set of genes when the reaction was carried out in 5-mL culture tubes with 100 μM quercetin under optimized conditions. Bioconversion was further improved by 98 % when the reaction was scaled up in a 3-L fermentor at 36 h. 相似文献
98.
99.
The fate of cyanobacterial detritus in the food web of Lake Taihu: a mesocosm study using 13C and 15N labeling 总被引:1,自引:0,他引:1
Jinlei Yu Yanmin Li Xiaoling Liu Kuanyi Li Feizhou Chen Ramesh Gulati Zhengwen Liu 《Hydrobiologia》2013,710(1):39-46
The ecosystem of the highly eutrophic Lake Taihu (China) is seriously affected by recurrent cyanobacterial blooms, but little is known about the contribution made by cyanobacteria to the food web. In this study, we investigated the fate of detritus of the cyanobacterium Microcystis in the food web of Lake Taihu through a 19-day mesocosm experiment using stable-isotopic tracers of carbon (13C) and nitrogen (15N). 13C- and 15N-labeled Microcystis detritus was added to the mesocosm tanks and tracked through different elements of the food web. We found clear enrichment with both 13C and 15N in some zooplankton species, including Daphnia, Diaphanosoma, and Sinocalanus, which suggests that these zooplankters can utilize cyanobacterial detritus as a food source. Benthic animals, chironomid larvae and Limnodrilus, also showed pronounced increases in 13C and 15N, but the isotope increase was relatively smaller in the gastropods, Radix sp. and Bellamya sp., implying that they either exploited this food source differently or responded slower than the zooplankton, which apparently grew faster than the snails. Our study suggests that cyanobacterial detritus, originating almost wholly from the bloom-forming Microcystis, is an important food source for both planktonic and benthic food webs in eutrophic lakes such as Lake Taihu. 相似文献
100.
Sediments are of key importance in determining the nutrient levels of water in shallow lakes as they can act as either source or sink for phosphorus (P) depending on environmental conditions, sediment characteristics, and external nutrient loading. We examined the role of benthic algae in the P cycling between sediment and overlying water in experiments using 32P as a tracer. Sediment and water samples were collected from Huizhou West Lake, a shallow, eutrophic waterbody located in Huizhou City, South China. Laboratory cultured benthic algae were transferred to cover the sediment core in tubes. When 32P was added to the water in experimental tubes containing sediment cores with and without benthic algae, 32P activity after 48 h was significantly lower in the tubes with algae, indicating that benthic algae removed P from the overlying water. When the tracer was injected into the sediment, 32P activity in the water overlying sediment with benthic algae was substantially lower than in tubes with naked sediment, suggesting that benthic algae reduce the release of sediment P. Oxygen levels were significantly higher in the upper 3 mm of the sediments covered by benthic algae; thus, we hypothesized that oxygen produced by the algae helps inhibit the release of P from the sediment. Our study demonstrates that benthic algae are capable of reducing P levels in water overlying the sediment, suggesting that loss of benthic algae during eutrophication triggered by impoverished light conditions may accelerate the shift in shallow lakes from a clear water to a turbid state. 相似文献