use of enzyme-linked immunosorbent assay [ELISA] for quantitative detection of potato virus Y in potato and other test plants.

In this study, ELISA was used to detect potato virus Y [PVY] in crude extracts of virus preparations from artificially infected leaves and tuber sprouts of different potato cultivars as well as in extracts and intact leaf discs of some hosts such as potato hybrid A6, tobacco, wild tobacco, tomato, wild tomato, pepper, Physalis floridana, Datura metel, D. Stramonium, Hyoscyamus muticus, Chenopodium amaranticolor, C. Quinoa, egg plant, Solanum nigrum, Gomphrena globosa and in some other herbaceous test plants. ELISA was a rapid and sensitive method enabling PVY to be detected three days after the inoculation of potato seedlings. The best stage of plant development for PVY detection in potato sprouts was 55 days after planting. It was possible to detect PVY by ELISA in intact leaf discs without the homogenization of Enab El-Deeb, potato, pepper, tomato, Datura metel, wild tobacco plants and gave a positive reaction with extracts containing PVY, but not with the other five plant viruses

Response of nitrogen components of tomato plants to potato virus- Y infection

Changes in nitrogen components of leaves of susceptible [Lycopersicon esculentum cv. Moneymaker] and resistant [Lycopersicon pimpinellifolium L.] tomato species, at various intervals post- inoculation with Yo group [common strain of potato virus Y [PVY]] were recorded. In susceptible tomato species, virus infection lowered the total nitrogen content as a result of decreased amino peptide, nitrate and total nitrogen components. The maximum decrease was recorded after 28 days post-inoculation. The remaining components were not affected by the infection, but the insoluble nitrogen increased, reaching maximum at 14 and 21 days post-inoculation. In resistant tomato species, virus infection stimulated total nitrogen accumulation as a result of increased peptide, nitrite and insoluble nitrogen contents. The effect was most pronounced at 14 days post- inoculation. The other components were less than in the control. The drop reached its maximum after 7, 21 and 28 days post-inoculation

Phosphorus distribution in healthy and potato virus Y-infected tomato plants

The influence of Y degree group of the common strain of potato virus Y [PVY] on the amount and distribution of phosphorus in leaves, stems and roots of the susceptible [Lycopersicon esculentum cv. [Money maker]] and resistant [Lycopersicon pimpinellifolium L.] tomato species at 1/2,1, 5,15, 25 and 35 days post infection was studied. During the first days post infection, the infected leaves of the susceptible tomato showed higher organic and total soluble phosphorus content while the inorganic phosphorus remained unchanged. By the end of the experiment, the inorganic and RNA phosphorus contents were lower than in the healthy leaves .PVY infection lowered the DNA-P content during most periods post infection except on the first and fifth day. It also increased the other insoluble and decreased the total insoluble phosphorus contents. During the whole experimental period, the infected stems were low in their soluble phosphorus components and high in the DNA-P whereas the RNA and the other insoluble phosphorus were not affected. Also the virus did not cause any significant change in the soluble fractions of the roots but their RNA and other insoluble phosphorus decreased whereas the DNA and total insoluble phosphorus contents were not affected. In the resistant tomato, the organic and total soluble phosphorus of the inoculated leaves significantly increased but the inorganic phosphorus remained unchanged during the fifth day post inoculation onwards. The RNA-P decreased whereas the DNA, other insoluble and total insoluble phosphorus increased. Infected stems had lower soluble and insoluble phosphorus components except DNA-P that increased. In roots, the soluble phosphorus components increased but the RNA and other insoluble phosphorus components decreased. The distribution of the different phosphorus fractions revealed that PVY infection increased the organic phosphorus and decreased the DNA-P and RNA-P of the leaves of the susceptible tomato plants and also decreased the organic phosphorus and increased the DNA and RNA phosphorus of the stems and roots. In resistant tomato, PVY increased the DNA-P and decreased the organic and RNA phosphorus distribution in leaves while in stems and roots the virus decreased the inorganic and DNA phosphorus and increased die RNA-P

Carbohydrate content of some potato virus Y-diseased solanaceous plants

Different carbohydrate components, viz. total soluble reducing and non reducing sugars and starch were compared in leaves of four solanaceous plants namely Lycopersicon esculentum cv. Money maker [susceptible tomato]; Lycopersicon pimpinellifolium L. [resistant tomato]; Capsicum annuum cv. "California Wonder" [pepper] and Solanum nigrum var. judaicum [Enab El-Deeb] at different intervals after inoculation with an isolate belonging to Y° group of the common strain of potato virus Y [PVY] studies indicate that: i - In susceptible tomato: virus infection lowered significantly the total carbohydrate content and starch content and decreased also the monosaccharide content but increased sucrose concentration. ii- In resistant tomato: virus infection decreased significantly all carbohydrate fractions except only the monosaccharides. iii- In pepper: virus infection lowered the total carbohydrate content as a result of decreased monosaccharides, sucrose and starch components .iv- In Enab El-Deeb: virus infection also decreased the total carbohydrate as well as the starch and total soluble sugars

Effect of some water soluble vitamins on potato virus Y infectivity I Effect of thiamine hydrochloride and riboflavin

This work was carried out to study the effect of various concentrations of eithe thiamine hydrochloride [vitamin B1] or riboflavin [vitamin B2], i.e. 100, 500, 1000 and 2000 ppm, on PVY infectivity both in vitro and in-vitro. In-vitro: Thiamine hydrochloride caused a highly significant reduction in PVY infectivity at 2000 ppm after 1 and 3 hours storage period, and a significant reduction in PVY infectivity was observed. In-vivo: A highly significant reduction in PVY infectivity was occurred at 2000 ppm of thiamine hydrochloride when rubbed immediately before and after inoculation. No significant reduction was observed in case of riboflavin. Accordingly, thiamine hydrochloride [vitamin B1] was more effective in reducing PVY infectivity than riboflavin vitamin B2

Effects of auxins on the infectivity of potato virus Y in hypersensitively reacting datura

Datura metel plants reacting hypersensitively to potato virus Y were used to test the effects of the natural auxin indoleacetic acid [IAA] and the synthetic auxin alpha-naphthylacetic acid [NAA] on the infectivity of the virus. The virus infectivity expressed as percentage of plants showing infection, decreased by increasing the auxin concentration from 10 to 200 ppm and by lengthen in the storage period from 60 to 180 min. Both IAA and NAA inhibited the virus infectivity in-vitro to a considerable extent. Complete inhibition was achieved when the virus was stored for 60 and 180 min with 200 ppm NAA. Preinoculation spraying with IAA and NAA was more effective in inhibiting the virus infectivity than postinoculation spraying. NAA was more effective in reducing PVY activity than IAA

Studies on the effects of some alkaloids and alkaloidal salts on potato virus Y infectivity: I Effect of alkaloids

The inhibitory properties of two alkaloids, ephedrine and caffeine, which belong respectively to the phenylalkylamine group and to the purine group, were evaluated against the mosaic symptoms produced by PVY on Datura metel plants. Each alkaloid was either mixed with the virus inoculum or rubbed to the leaves before and after inoculation. When ephedrine - at various concentrations- was mixed with virus inoculum, the infectivity decreased gradually with increasing concentration and with lengthened time of contact, between ephedrine and virus form 60 to 180 min. With caffeine, the infectivity increased by increasing its concentration and decreased by lengthening the time of contact between caffeine and virus. When applied by rubbing, immediately [zero time] and 24 hours before and after virus inoculation ephedrine was superior to caffeine in inhibiting the virus infectivity