The effect of suppression of UDP-glucose pyrophosphorylase (UGPase, UTP ±-D-glucose-1-phosphate uridylyl transferase, EC 2.7.7.9) on carbohydrate metabolism in potato tubers was investigated. ...Constructions expressing a UGPase-specific ribozyme or a UGPase antisense RNA based on the genomic sequence, each under the control of the 35S promoter of the Cauliflower Mosaic Virus, were tested. Out of 103 plants transformed with the constructs, only 13 showed levels of UGPase activity significantly different from the control. No transgenic plants, carrying either construct, expressed an enzyme activity lower than 50-60 % of the control. Plants of seven clones were grown in the field, and UGPase activity, and the level of sugars were measured in the tubers. After storage at room temperature for one week, tubers of six of these had sucrose levels significantly (P<0.05) lower than in control tubers. In tubers of four clones, the difference was maintained after two months storage at 10 °C, and in two clones it persisted two months after storage at 6 °C. The results indicate that UGPase limits the rate of UDP-glucose synthesis in stored tubers and potentially can be used to control the reduced-sugar accumulation during cold-storage.
Leaf spot, caused by the fungus Cercospora beticola, is an endemic disease of sugarbeets in the USA's Northern Great Plains. The disease is managed by crop rotation, resistant cultivars and timely ...fungicide applications. Cercospora leaf spot usually appears in the last half of the growing season, and two to four fungicide applications are made for disease control. The most frequently used fungicides are triphenyl tin hydroxide, thiophanate methyl, tetraconazole, trifloxystrobin and pyraclostrobin. C. beticola has the ability to adapt and become less sensitive to the fungicides used to control them. We have conducted extensive testing of C. beticola isolates collected from the sugarbeet production regions of ND and MN for sensitivity to the commonly used fungicides in order to develop efficacious and sustainable fungicide recommendations. A combination of radial growth and spore germination were used to monitor changes in fungicide sensitivity. Results indicate that triphenyl tin tolerance is declining; resistance to thiophanate methyl is widespread and not declining; sensitivity to tetraconazole is relatively stable, but there is a slow increase in the number of resistant isolates. Sensitivity to pyraclostrobin and trifloxystrobin also remains relatively stable, but there are some isolates with a decrease in sensitivity. An integrated approach utilizing many disease control factors will be necessary for continued Cercospora leaf spot management.
The organization of the gene encoding potato UDP-glucose pyrophosphorylase, one of the key enzymes of carbohydrate metabolic pathway is presented. The gene cloned from cultivar (cv.) Lemhi consists ...of a 6.6-kb structural and a 1-kb regulatory region. The structural region contains 20 exons and 19 introns. The coding sequence with exception of three bases is identical with the
UGPase cDNA previously cloned from Danshaku-Imo cv.
Katsube et al. (1990)UDP-Glucose pyrophosphorylase from potato tuber: cDNA cloning and sequencing. J. Biochem. 108, 321–326. The largest intron contains a tandem repeat consisting of 50 nt core units. A putative polyadenylation site is situated 79 bp downstream of the translation stop codon. A transcription start point (
tsp) and a putative TATA-box were located 84 bp and 141 bp upstream of the translation start, respectively. The regulatory region contained general enhancer, suppressor, and regions responsible for tissue specificity of
UGPase expression.
Powdery scab is a serious disease of potatoes (Solanum tuberosum L.) that can cause extensive surface defects on susceptible potato cultivars. The pathogen, Spongospora subterranea (Wallr.) Lagerh. ...f. sp. subterranea J. A. Tomlinson, is an important concern in seed potato production because current seed certification standards in North Dakota have a zero tolerance for this pathogen. Powdery scab had not previously been identified in North Dakota. Until recently this disease was not thought to be present in U.S. commercial potato-producing areas. Powdery scab has now been shown to be more widely distributed than previously thought (1), having been identified in several locations in eastern and western North America. However, environmental conditions in North Dakota, including high soil pH, low rainfall, and high temperatures, are not considered favorable for powdery scab development. Diseased potatoes were found in a field from Griggs County, ND, in the fall of 1994 and characteristic cystosori were present in erumpent lesions on infected tubers. The field was an irrigated circle planted to three different cultivars. The cultivars Goldrush and Red Norland were symptomless, while cv. Red La-Soda was severely affected. Up to 30% of the tuber surfaces were diseased and disease incidence approached 25%. The infected crop was destroyed. Pathogenicity was confirmed by planting pieces of diseased tuber tissue adjacent to healthy seed pieces of Russet Burbank. Transmission of the obligate parasite occurred naturally by simulating conditions that were favorable for infection, acidic potting mix (Jiffy-Mix) maintained at a high water potential. Progeny plants were found to be infected on both tubers and roots after 60 days. Control plants that were not exposed to diseased tuber pieces were unaffected. North Dakota, a major seed-potato-producing state, ships seed to every other potato-producing area in the U.S. and much of Canada. Infected seed shipped to areas with a favorable environment for disease development may result in crops becoming diseased and unmarketable. The cooler temperatures and higher than normal rainfall during the 1992 to 1995 seasons may account for powdery scab development in North Dakota. Recent increases in irrigated agriculture and potato production in North Dakota could lead to the infestation of new areas, restricting the value of that land for potato production. Reference: (1) B. Christ et al. Am. Potato J. 65:583, 1988.
This book provides insights into the research and programs currently related to schistosomiasis, and uses these insights to project into future years of work on schistosomiasis, from research to ...public health interventions. A secondary goal is to initiate conversations among those working on schistosomiasis about the future of their field, and by doing so lead to constructive efforts to identify and address the most critical questions and challenges related to schistosomiasis. The first 4 chapters address schistosome phylogenetics, gene expression, and the overall genome. The next 3 chapters explore the host-schistosome interaction at the larval to adult worm interface. The following 3 chapters explore the development of the host immune response to eggs, granuloma formation and factors affecting the development and regulation of immunopathology. The next 4 chapters address public health concerns, and concludes with a chapter addressing the schisms that sometimes exist between basic research to implementation of control schemes.
Three Phytophthora infestans (Pi) resistance assessment methods were tested in sixty potato breeding selections from selected parents with reported resistance to Pi to correlate foliar and tuber ...resistance. Assessment methods were: (a) tuber inoculation, (b) foliar field, and (c), foliar greenhouse by detached leaf assay (DLA). DLA and tuber assays were conducted in replicated trials in two years using an inoculum suspension of 2 x 10 super(4) zoospores ml super(-1). Tubers were inoculated with a 10 kl of Pi inoculum in three eyes on the bud end, incubated for 14 days and evaluated for lesion severity. For the DLA, leaves were inoculated with 30 kl of inoculum and after five days of incubation, rated for disease using a zero to four scale. In the field, plants were inoculated and evaluated weekly for disease severity and an AUDPC calculated for each selection. A significant difference in genotype reaction to the disease was observed by the three methods. Selections ND8527B-94, ND028945B-4, ND028801CB-1, ND8277B-5 and ND6961B-21PY showed high levels of resistance to Pi by all three methods. One year of foliar field data did not correlate with tuber (r = 0.27 P < 0.033) or DLA (r = 0.39 P < 0.016 for 2007 and r = 0.30 P < 0.017 for 2008), however, DLA was able to detect 84.7% of the selections that showed high to moderate resistance in the field, and may be useful as a screening method for predicting Pi resistance in families from directed crosses for late blight resistance.
The diffusion of deoxynivalenol (DON) into apparently healthy tissue of potato tubers affected with dry rot caused by Fusarium graminearum (Fg) is a food safety concern for potato growers and ...processors, because of potential adverse effects to human health. The objective of this study was to determine the presence and distribution of DON and Fg along in potato tubers with dry rot caused by Fg. Potato tubers were inoculated with two DON-producing Fg isolates in the bud end and incubated for 3 to 7 weeks at 15C. The evaluation consisted in Fg recovery on half strength PDA, and DON quantification by GC-MS of rotted tissue and healthy potato tuber sections distance 1, 2 and 3 cm distal from the decay margin. After 3 weeks of incubation Fg was recovered from 60, 25, 11, and 3% of the lesion and 1, 2, and 3 cm from the lesion. After 7 weeks Fg was recovered from 86, 68, 64, 53% respectively, showing a large increase of Fg into healthy tissue. But after 3 weeks of incubation, DON levels were 11.72, 0.05, < 0.04, and <0.04 ppm, in the lesion and 1, 2, 3 cm from the lesion, respectively; and after 7 weeks of incubation, DON was detected in 19.11, 0.54, <0.04, and <0.04 ppm. This shows an increase of DON in the lesion and immediately adjacent (1 cm) to the decayed area, and a lack of diffusion into additional healthy tissues with the advancing Fg hyphae. Based on this work, DON can be safely removed from tubers with dry rot by careful trimming of affected tissue.
White mold, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is a major concern to the dry bean (Phaseolus vulgaris L.) industry because it reduces yield. Incorporating partial physiological ...resistance (PPR) into bean is one strategy to combat the disease, but this requires a reliable screening technique. The objective of this work was to develop a reliable screening method to identify bean germplasm that express PPR to S. sclerotiorum. An in vitro method that assayed weight of calli formed on a medium amended with crude culture filtrate of S. sclerotiorum was evaluated. Hypocotyl explants of eight bean genotypes (six cultivars, a breeding line, and one plant introduction), taken from 7-d-old seedlings, were incubated for 15 d on a solid Murashige and Skoog-based medium, containing 5.0 micromolar kinetin and 2.5 micromolar picloram, and amended with 200 mL L-1 culture or control filtrate. Callus fresh weight, expressed as a percent of the control (CWPC), was analyzed over two runs. Lack of a genotype X run interaction, and a genotype effect (P 0.05) for CWPC indicated that this screening method gave repeatable results and was able to differentiate PPR among the eight genotypes. The field resistant 'Sierra' and 'C-20' had the greatest PPR, as indicated by high CWPC values, and the field susceptible 'UI-114' and 'Upland,' the least PPR. These results to fungal metabolites parallel field resistance of the genotypes, implicating PPR as an important component of the field reaction of a given genotype. The callus-weight assay may provide a way to differentiate dry bean germplasm for partial physiological resistance to S. sclerotiorum
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