THE USE OF RADIANT HEAT TO REDUCE THE INOCULUM LEVEL OF SILVER SCURF (HELMINTHOSPORIUM SOLANI) ON POTATO TUBERS (SOLANUM TUBEROSUM) BEFORE STORAGE

2003 ◽  
pp. 207-211 ◽  
Author(s):  
T.P.C. Johnson ◽  
B.W.W. Grout ◽  
C.F.H. Bishop ◽  
A. Perera
2005 ◽  
Vol 82 (2) ◽  
pp. 41-48 ◽  
Author(s):  
V. Hervieux ◽  
R. Chabot ◽  
J. Arul ◽  
R.J. Tweddell

Silver scurf of potatoes (Solanum tuberosum), caused by the fungus Helminthosporium solani, is an important surface-blemishing disease of potato tubers. The objective of the study was to evaluate the efficacy of different fungicides applied to potato seed tubers for control of silver scurf. Field trials were conducted in Québec province in 1998 and 1999. Potato seed tubers infected with H. solani were treated with either talc, fludioxonil, mancozeb, iprodione, thiabendazole, imazalil or azoxystrobin, and planted at three locations in 1998 and two locations in 1999. The results showed that, under our experimental conditions, the fungicides tested, applied as seed treatments, did not significantly influence total and marketable yields as well as silver scurf severity on daughter tubers at harvest and after different storage periods. In addition, this study showed the influence of the experimental locations on silver scurf development and suggests that soil inoculum plays a role in the epidemiology of the disease.


Author(s):  
M. B. Ellis

Abstract A description is provided for Helminthosporium solani. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Solanum tuberosum. DISEASE: Silver scurf of potato tubers. It causes a blemish of the skin which becomes discoloured brown or silvery in patches, more conspicuous in spring especially on greened tubers. The silvery appearance is most apparent when tubers are washed. Sometimes the affected areas become dry and flake-off. Where infection is severe under storage conditions the entire surface of the tuber may become sooty owing to the presence of large numbers of conidiophores and conidia. GEOGRAPHICAL DISTRIBUTION: CMI Map 233 shows distribution up to 1951. Countries from which the disease has been reported since then include: Greece, India, Jersey, Mozambique, Peru, Switzerland, U.S.S.R., Venezuela. TRANSMISSION: Through infected seed tubers.


2004 ◽  
Vol 22 (4) ◽  
pp. 690-695 ◽  
Author(s):  
Marcos G. Cunha ◽  
David M. Rizzo

A new potato tuber disease has been observed in the Tulelake region, California, USA, since 1995, with tuber symptoms suggestive of silver scurf disease (Helminthosporium solani). In this work we isolated, identified and demonstrated the nature of the causal agent of this potato disease in California. In addition, the distribution of H. solani in potato fields and the inoculum potential at harvest time were investigated. Disease progress and H. solani spore populations were also characterised under commercial storage conditions. The main fungal genera associated with potato tubers in storage were Helminthosporium solani, Colletotrichum sp., Fusarium sp., and Rhizoctonia sp. The results of Koch's postulates indicated that H. solani is responsible for the outbreak of silver scurf in the Tulelake region. In a disease survey in three commercial potato fields naturally infested, H. solani infections occurred in all fields. However, the extension of the infections differed significantly between the fields. During potato storage, silver scurf usually increased over time. The percentage of the tuber surface covered by silver scurf varied from 3.5% up to 35.5% during the storage period. The number of H. solani lesions per tuber also progressively increased from 6% up to 35%, six months after storage. H. solani spore populations also increased over time in all studied potato stores; nevertheless, they followed no consistent pattern, exhibiting multiple and variable peaks of increase and reduction during the period of storage.


Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 717-720 ◽  
Author(s):  
M. Michaud ◽  
C. Martinez ◽  
A.-M. Simao-Beaunoir ◽  
R. R. Bélanger ◽  
R. J. Tweddell

Silver scurf, caused by the fungus Helminthosporium solani, is an important disease affecting potato tubers. Control of the disease has been hampered by the development of H. solani strains resistant to thiabendazole, the only fungicide used in postharvest treatment. As a result, alternative control strategies are needed. In this study, 100 selected soil samples from the province of Québec were tested for their effect on silver scurf development on potato tubers. The results showed that 10 soils were able to decrease silver scurf development on tubers incubated at 10, 15, or 24°C. Many microorganisms were isolated from these soils and tested for their individual ability to reduce H. solani development using a whole-tuber assay. Several of them, including Alcaligenes piechaudii, Aquaspirillum autotrophicum, Arcanobacterium haemolyticum, Arthrobacter oxydans, Bacillus mycoides, Kocuria rosea, Streptomyces griseus, and a fungus of the class Zygomycetes displayed an ability to reduce the development of silver scurf on potato tubers at 10, 15, or 24°C. These results can find useful applications toward a biocontrol program of potato silver scurf as postharvest or seed tuber treatment.


Plant Disease ◽  
2007 ◽  
Vol 91 (4) ◽  
pp. 460-460 ◽  
Author(s):  
S. M. Tian ◽  
Y. C. Chen ◽  
M. Q. Zou ◽  
Q. Xue

Silver scurf disease of potato (Solanum tuberosum) caused by Helminthosporium solani Durieu & Mont. occurs worldwide. Severe occurrence of the disease, the resulting weight loss of stored potatoes, and lower market classes of potato caused by the fungus have been documented in Europe and North America (1). Tubers infected with the pathogen develop tan-to-gray lesions that have a characteristic silvery appearance when moist. In 2005, gray spots with a defined margin and silvery appearance when seen against light were observed on potato tubers of cv. Weishu No. 1. The silver symptoms were distinguished from those of black rot disease of potato caused by Colletotrichum coccodes. The potato tubers were obtained from Weichang County of Hebei Province, North China. Conidia were scraped from the spots with a sterile scalpel and identified primarily as the fungus H. solani on the basis of morphological characters of the spores. The fungus was isolated, purified, and cultured on potato dextrose agar (PDA) amended with penicillin and streptomycin. To produce conidia, the fungus was incubated on V8 juice medium at 20 ± 2°C for 15 days under near-UV light (360 to 400 nm, 12-h light/dark cycles). The culture colony developed slowly and is gray to brown. Conidia form in whorls on conidiophores that are black, unbranched, irregular, and multiseptate. Conidia are appreciably tapered, straight or slightly curved, brown, thick walled, and have two to eight pseudosepta. The size of the conidia ranged from 14 to 70 μm long and 4 to 9 μm wide. The spore suspension was adjusted to 1.5 × 105 spores per ml by using sterile distilled water containing 0.2% Tween 20. Twenty healthy tubers were washed with distilled water and then inoculated by spraying the spore suspension onto the surface with a hand atomizer, while 10 washed tubers were sprayed with distilled water as controls. Inoculated tubers were kept in containers covered with plastic and placed in an incubation chamber at 20°C for 3 weeks. Gray-to-brown blemishes with a silvery appearance as described above were observed on tubers inoculated with the fungus and the tuber surface areas infected were from 1 to 10%, whereas no infection was visible on tubers inoculated with water. The causal agent was reisolated, cultured, and identified microscopically as H. solani. H. solani has been identified from potato tubers in Yunnan Province, Southwest China (2), but to our knowledge, this is the first report of H. solani causing silver scurf of potato in Hebei Province, North China. References: (1) D. Errampalli et al. Plant Pathol. 50:141, 2001. (2) K. Y. Ryu et al. China Potato. 15:195, 2001.


Author(s):  
E.O. Shmelkova ◽  
M.A. Slugina ◽  
A.A. Meleshin ◽  
E.V. Romanova

Работа посвящена разработке и тестированию универсальных праймеров для ПЦР-амплификации полноразмерных генов-ортологов β-фруктофуранозидазы (кислой вакуолярной инвертазы) у видов и сортов картофеля (Solanum tuberosum). Крахмал – основной источник энергии и резервный углевод, накапливающийся в амилопластах клубней. Образовавшаяся в результате фотосинтеза молекула глюкозы при реакции с фруктозой образует сахарозу – основную транспортную форму углеводов в растении. В клубни сахароза доставляется по флоэме (апопластный путь), где в межклеточном пространстве расщепляется до глюкозы и фруктозы, которые затем проникают в клетки паренхимы. Глюкоза служит в дальнейшем субстратом для синтеза крахмала в амилопластах. Однако при воздействии пониженных температур крахмал в клубнях картофеля разрушается до редуцирующих сахаров. Параллельно этому процессу идет ресинтез сахарозы до глюкозы и фруктозы за счет фермента кислой вакуолярной инвертазы (β-фруктофуранозидазы), кодируемой геном Pain-1. В совокупности эти процессы приводят к избыточному накоплению моносахаров в клубнях картофеля, так называемому холодовому осахариванию (cold-induced sweetening). При этом создаются условия для интенсивного образования меланоидинов, вызывающих потемнение мякоти картофеля, что значительно ухудшает товарное качество продукта. Таким образом, изучение гена Pain-1, кодирующего вакуолярную инвертазу, а именно, его идентификация и анализ структуры – важная задача, необходимая для поиска доноров, устойчивых к холодовому осахариванию. Первоочередная задача для этого – разработка и тестирование праймерных комбинаций, позволяющих амплифицировать полноразмерный ген у диких видов картофеля, а также сортов и линий культивируемого картофеля (S. tuberosum). В данной работе приведены результаты разработки и тестирования универсальных праймеров, с помощью которых можно амплифицировать как полноразмерные гены-ортологи, так и фрагменты гена Pain-1, а также подобраны оптимальные условия для проведения ПЦР реакции. Было разработано 6 праймерных комбинаций (PainF – PainR, PainF – Pain1exR, Pain1exF – Pain3exR, Pain2inF – Pain2inR, Pain3exF – Pain5exR, Pain5exF – PainR), среди которых комбинация PainF – PainR позволяла амплифицировать полноразмерный ген, остальные – внутренние и будут использованы в дальнейшем при секвенировании фрагментов исследуемого гена. Эти праймеры были успешно протестированы на 15 образцах, включающих представителей пяти дикорастущих видов картофеля (S. gourlay, S. chacoense, S. pinnatissectum, S. stoloniferum, S. vernei) и десяти сортов российской и зарубежной селекции (Гала, Ласунок, Ред Скарлетт, Рассет Бербанк, Мирас, Башкирский, Жуковский ранний, Матушка, Елизавета, Сударыня).The purpose of research is design and testing of universal primers for PCR amplification of full-length-fructofuranozidase orthologs genes (acid vacuolar invertase) in wild species and potato (Solanum tuberosum) varieties. Starch is the main source of energy and a reserve carbohydrate, that accumulates in tubers amyloplasts. Glucose molecule, produced by photosynthesis, reacts with fructose and forms sucrose, which is the main transport type of carbohydrates in the plant. In the tuber, sucrose is delivered via phloem (apoplast), where it splits into glucose and fructose, which then go to the parenchyma cells. Glucose is a further substrate for the starch synthesis in amyloplasts. However, low temperatures influence on potato tubers leads to starch break down to reducing sugars. In parallel to this process there is happens resynthesis of sucrose to glucose and fructose by acid vacuolar invertase enzyme (β-fructofuranosidase) encoded by Pain-1 gene. Together, these processes lead to an excessive accumulation of monosaccharides in potato tubers. This process also called as cold-induced sweetening. It creates conditions for the intensive formation of melanoidins, which cause a potato tubers darkening, which considerably impairs the commercial quality of the product. Thus, the study Pain-1 gene that encodes the vacuolar invertase (its identification and structure analysis) is an important task required for the search of donors resistant to cold-induced sweetening. The primary task for this is the design and testing of primer combinations that allow to amplify the full-length gene in wild potato species, varieties and lines of cultivated potato. In this work, we develop and test universal primers, that can amplify both full-length orthologs and fragments of the Pain-1 gene, and also select the optimal conditions for carrying out the PCR reaction. Summary. The purpose of research is design and testing of universal primers for PCR amplification of full-length-fructofuranozidase orthologs genes (acid vacuolar invertase) in wild species and potato (Solanum tuberosum) varieties. Starch is the main source of energy and a reserve carbohydrate, that accumulates in tubers amyloplasts. Glucose molecule, produced by photosynthesis, reacts with fructose and forms sucrose, which is the main transport type of carbohydrates in the plant. In the tuber, sucrose is delivered via phloem (apoplast), where it splits into glucose and fructose, which then go to the parenchyma cells. Glucose is a further substrate for the starch synthesis in amyloplasts. However, low temperatures influence on potato tubers leads to starch break down to reducing sugars. In parallel to this process there is happens resynthesis of sucrose to glucose and fructose by acid vacuolar invertase enzyme (β-fructofuranosidase) encoded by Pain-1 gene. Together, these processes lead to an excessive accumulation of monosaccharides in potato tubers. This process also called as cold-induced sweetening. It creates conditions for the intensive formation of melanoidins, which cause a potato tubers darkening, which considerably impairs the commercial quality of the product. Thus, the study Pain-1 gene that encodes the vacuolar invertase (its identification and structure analysis) is an important task required for the search of donors resistant to cold-induced sweetening. The primary task for this is the design and testing of primer combinations that allow to amplify the full-length gene in wild potato species, varieties and lines of cultivated potato. In this work, we develop and test universal primers, that can amplify both full-length orthologs and fragments of the Pain-1 gene, and also select the optimal conditions for carrying out the PCR reaction. In total 6 primer combinations were designed (PainF - PainR, PainF - Pain1exR, Pain1exF - Pain3exR, Pain2inF - Pain2inR, Pain3exF - Pain5exR, Pain5exF - PainR), where PainF - PainR primer combination allowed to amplify a full-sized gene, the rest are internal and will be used in the further fragments sequencing of the β-fructofuranosidase gene. These primers were successfully tested on 15 samples, including five wild species of potato (S. gourlay, S. chacoense, S. pinnatissectum, S. stoloniferum, S. vernei) and ten varieties of Russian and foreign breeding (Gala, Lasunok, Red Scarlet , Rasset Burbank, Miras, Bashkirsky, Zhukovsky ranniy, Matushka, Elizaveta, Sudaryna).


2017 ◽  
Vol 72 (6) ◽  
pp. 393-396
Author(s):  
Liangyan Liu ◽  
Jun Han ◽  
Yong Shen

AbstractTwo new defensive constituents, solatuberenol A (1) and 3-O-β-d-glucopyranosyl stigmasta-5(6),24(28)-diene (2), were isolated from the potato tubers (Solanum tuberosum) infected with late blight disease. Their structures were identified by extensive spectroscopic analysis, including HRMS, IR, UV, 1D/2D NMR, ECD and quantum chemical calculations. Compounds 1 and 2 showed moderate activity against Phytophthora infestans with mycelia-growth inhibition of 30.1% and 52.4%, respectively, at the concentration of 500 ppm.


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