30 research outputs found
A Meridic Diet for the Colorado Potato Beetle, Leptinotarsa decemlineata (Say)
No full textFoliage of the potato, Solanum tuberosum (L.), was analyzed previously to determine its nutritional content. This information was used to help develop a meridic diet for rearing the Colorado potato beetle, Leptinotarsa decemlineata Say. Various test diets were prepared, and types and concentrations of proteins, amino acids, carbohydrates, and ascorbic acid were tested for their influence on growth and weight gain of larvae reared from the egg stage on diet. At 2.8% protein or less, neither egg albumin nor casein produced adult beetles. Adults were reared with casein concentrations of 3.0 and 4.2%, but not at 5% casein. An abbreviated list of foliar amino acids was as effective as the complete foliar complement in the rearing of adults. Oat flour or potato flakes were suitable carbohydrate sources for rearing to the adult stage. The composition of a meridic diet is presented which was used for rearing the Colorado potato beetle from the egg to the adult stage, in the absence of host plant material.</jats:p
Oxygen metabolism in plantlbacteria interactions: characterization of the oxygen uptake response of plant suspension cells
No full textIn recent years the accumulation of reactive oxygen species (ROS) has been studied in plant cell suspension systems treated with bacterial pathogens. However, the associated utilization of molecular oxygen has not been well characterized. Using a multi-electrode oxygen analyser, the rates of oxygen consumption by tobacco cells during bacterial interactions were monitored. Heat-killed (HK) bacteria, which initiate an immediate ROS response in plant cells, were used as an elicitor to avoid complications of oxygen consumption by viable bacteria. An increase in oxygen uptake by the tobacco cells occurred within 4 min after addition of HK-bacteria and lasted for about 10 min, returning to a steady state at approximately twice the initial basal rate. The initial burst in oxygen uptake coincided with production of H202. Calculation of the total oxygen consumption by the plant cells indicated that less than 5 % of the increased oxygen uptake was utilized in ROS production. Use of respiratory inhibitors indicated that respiration, especially the cytochrome pathway, played a significant role in this response. Results from the use of K-252, a protein kinase inhibitor, and DPI, an inhibitor of membrane bound NADPH oxidases, indicated that triggering of the oxygen uptake response may involve protein phosphorylation and is at least partially activated by the membrane bound NADPH oxidase activity. The involvement of mitochondrial respiration in the oxygen uptake response described here indicates that early events in plant recognition of pathogens involves more of the cellular machinery than previously hypothesized
Horizontal resistance insolanum tuberosum to colorado potato beetle (leptinotarsa decemlineata say)
No full textOxidative metabolism in plant/bacteria interactions: characterization of a unique oxygen uptake response of potato suspension cells
No full textPlant suspension cells have been shown to respond to bacteria or microbial elicitors by producing active oxygen as well as increasing oxygen uptake. Here we characterize a unique two stage oxygen uptake response of potato suspension cells to heat-killed bacteria. Stage 1 occurred within minutes after the addition of heat-killed bacteria; the potato suspension cells responded with a rapid increase in oxygen uptake and reached a steady state approximately 50 % greater than the initial basal rate. Stage 2 began 20-30 min after this new steady state was achieved and was characterized by a slow increase in the oxygen uptake rate over the remaining 90 min period. Calculation of the total oxygen consumption by the plant cells indicated that only a small fi-action of the increased oxygen uptake was due to the concomitant production of reactive oxygen species. The protein kinase inhibitor, K-252, inhibited the oxygen uptake response by 80-90 %, suggesting the involvement of protein phosphorylation in the oxygen uptake response. The alternate oxidase inhibitor, SHAM, inhibited the elicited oxygen uptake response by about 25 % while a combination of SHAM and KCN almost completely blocked respiration as well as the elicited response. The data indicate that mitochondrial respiration and, in particular, the alternate oxidase, play a significant role in the elicited oxygen uptake response of potato cells
MEASURING RESISTANCE TO THE COLORADO POTATO BEETLE (COLEOPTERA: CHRYSOMELIDAE) IN POTATO
No full textA sensitive test was sought that could be used to detect small differences in resistance to the Colorado potato beetle (CPB) in Solanum species. Three tests were evaluated and compared. One test compared adult CPB foliage consumption of leaf disks from a susceptible potato cv, S. tuberosum, with disks from two S. chacoense clones. The second test compared weight gain on foliage from the three plants by 4th instar larvae and the third test compared larval development rate and mortality. With sufficient replication all three of the tests could detect significant differences between each of the test clones. The most sensitive test measured the stage of development of neonate larvae after feeding on test plants four days. This test required only four replicates to detect a 50% difference from the overall mean assuming an alpha level of 0.05 and a beta level of 0.10.</jats:p
Leptines and Other Glycoalkaloids in Tetraploid Solanum Tuberosum X Solanum Chacoense F2 Hybrid and Backcross Families
No full textPerformance of Colorado Potato Beetle Larvae, Leptinotarsa Decemlineata (Say), Reared on Synthetic Diets Supplemented with Solanum Glycoalkaloids
No full textEffect of α-Tomatine and Tomatidine on the Growth and Development of the Colorado Potato Beetle (Coleoptera: Chrysomelidae): Studies Using Synthetic Diets
No full textGlycoalkaloids are found throughout the genera Solanum (potato) and Lycopersicon (tomato). Certain glycoalkaloids, i.e., α-tomatine, solanocardenine, and leptine, have been implicated as resistance factors to the Colorado potato beetle, Leptinotarsa decemlineata Say. The allelochemical properties of these glycoalkaloids have primarily been demonstrated by studies in planta, correlating Colorado potato beetle resistance with high levels of foliar glycoalkaloids: solanocardenine in S. neocardenasii, α-tomatine in S. pinnatisectum, and leptine in S. chacoense. Although the evidence that these glycoalkaloids mediate resistance is compelling, controlled analyses of Colorado potato beetle response to purified glycoalkaloids, fed to insects in synthetic diets, are necessary to characterize the allelochemic nature of these compounds. In this study, Colorado potato beetle reared on a meridic, synthetic diet supplemented with increasing concentrations of α-tomatine exhibit retarded growth and delayed development. These effects were evident throughout the insects' development, from egg to prepupal stage. Tomatidine (the aglycone of α-tomatine) has no effect on Colorado potato beetle, suggesting that the tetrasaccharide moiety of the glycoalkaloid is essential for insecticidal activity, consistent with a membrane-lytic mechanism of action.</jats:p
Partial Preparative Purification of the Glycoalkaloid Leptine I From Foliage of the Wild Potato Species Solanum Chacoense Bitter
No full textPotato late blight populations: migration, selection and chance?
No full textSince the 1970s, new genotypes of Phytophthora infestans introduced into many parts of the world have almost completely displaced the old, A1 clonal lineage. Despite introductions of both mating types, in many regions this has not resulted in sexually-recombinant populations becoming established, but in the evolution of new, but largely clonal populations. These may comprise several major clonal genotypes and sometimes undergo periodic upheavals when new fit genotypes appear by migration, infrequent recombination or other mechanisms. For example, the P. infestans population in Ireland consists of a number of clones all of the A1 mating type: A2 mating type strains, although introduced in the 1980s, do not appear, so far, to have become widely established in the population and are rarely detected. The population in Great Britain also appears clonal, but is currently undergoing major changes. In Taiwan, displacement of the old US-1 population took place within 2 years, but the new population is also A1 and clonal. In the USA, although numerous A1 and A2 genotypes have appeared since the early 1990s, only a limited number have been perpetuated. At present, in the eastern and mid-western states, the US-8 genotype, which first appeared in the mid 1990s, is dominant, but US-11 is the main genotype isolated from potato and tomato from Washington, Oregon, and Alaska, while US-14 and variants occur on both potato and tomato in Florida. There is currently evidence of the appearance of new genotypes in parts of the US, but it remains to be seen if these will displace existing ones. Thus, in some regions (e.g. Taiwan), the new genotypes belonged to only a single mating type, but in others, even where multiple genotypes of both mating types were introduced, only a few have been perpetuated. What mechanisms are involved? Field trials in Northern Ireland and Michigan using multiple potato cultivars and P. infestans genotypes showed that extreme selection occurred within the P. infestans populations at both locations. In Northern Ireland, there was a strong influence of cultivar; different genotypes dominated infection of different cultivars. Selection was partly due to aggressiveness to specific cultivars, but this did not fully explain the extreme selection in the field, other factors such as direct competition during the infection process may also play a role. In the US, the US-8 genotype proved the most aggressive and also dominated infection of all cultivars in the field: other genotypes were rarely detected. Additional selection occurs during the tuber phase. Studies in Belfast demonstrated that the cultivar influences which genotypes infect tubers; even where multiple genotypes have colonised foliage, few infect tubers. Over the winter, some genotypes may be lost by tuber rotting. A further bottle-neck occurs when epidemics are initiated by surviving infected tubers: field trials showed that when tubers inoculated with different genotypes were planted, generally only one successfully initiated foliar infection. Finally, the extreme efficiency of asexual reproduction in P. infestans, compared with the sexual cycle, must be important in perpetuating clonal genotypes in regions where tuber infection is frequent and infected tubers can survive the winter. However, none of these factors seems sufficient to explain why sexually-recombinant populations have apparently become established in some parts of Europe, including the Netherlands, Poland and the Nordic countries, yet, in many other regions, sexual recombination seems to be very infrequent or even absent. Barriers to successful recombination and perpetuation of sexual progeny may well be important: these merit further investigation. Above all, chance may play a crucial role, particularly in terms of the introduction and survival of new, fit genotypes of P. infestans by man, its principal vector.vokMyynti MTT Tietopalvelut 31600 Jokioine
