Effect Of Rust Infection Research Articles

Puccinia sambuci Infection of American Elderberry Plants

Elderberry rust (Puccinia sambuci Schwein.) Arthur (=P. bolleyana) (Arthur, 1921) disease is frequently found in commercial American elderberry (Sambucus nigra L. subsp. canadensis L.) plantings when an alternate host, Carex sp., is present. To evaluate potential infection periods of P. sambuci on elderberry plants, micrometeorological conditions were monitored. Rust symptoms were observed on elderberry on 5 Apr. 2016, and conditions favorable for possible infection were 9 to 18 °C, ≥3 hours of continuous leaf wetness, and ≥85% relative humidity. Studies were also conducted to ascertain whether P. sambuci with varying pustule numbers affects fruiting, berry puree quality, or vegetative growth. Fruit yield was reduced by 31% when potted ‘Bob Gordon’ elderberry averaged six rust pustules per plant compared with noninfected plants. In another experiment, field-grown ‘Wyldewood’ plants averaging 137 rust pustules/cane at harvest had 47% less fruit weight on canes than uninfected canes. Titratable acidity of fruit puree from plants was lower when plants had either 690 rust pustules/plant or 137/pustules/cane, but soluble solids and pH of puree were unaffected by P. sambuci infection. The effect of rust infection on vegetative growth of elderberry plants also varied with pustule numbers. With a low infection level (six pustules per plant), P. sambuci did not induce premature leaf loss on ‘Bob Gordon’ plants or adversely affect shoot dry weight at the end of the growing season. When P. sambuci infection on ‘Wyldewood’ plants was more severe (137 pustules/cane), greater leaf loss occurred on infected canes than on uninfected canes. At very high infection levels (690 pustules/plant), ‘Bob Gordon’ plant dry weight was reduced. Because of the potential for fruit yield loss on elderberry plants, control of P. sambuci at relatively low infection levels on this plant may be warranted. Strategies that eliminate or suppress the alternate host would likely reduce the P. sambuci inoculum and limit the potential for elderberry plant infection.

Interactions between the rust fungus Puccinia punctiformis and ectophagous and endophagous insects on creeping thistle

Summary Plant–pathogen–insect interactions may have various outcomes that are of great interest when considering the combined use of insects and pathogens in the biological control of weeds. Here effects of rust infection on herbivore attack and of herbivory on rust infection were analysed to ensure that these possible control agents do not impede each other. The system studied was the weed creeping thistle Cirsium arvense, the specialized rust fungus Puccinia punctiformis, and ectophagous and endophagous insect herbivores. On 20 sites around Göttingen, Germany, the abundance of ectophagous and endophagous insects on systemically rust‐infected and uninfected plants was quantified by suction samples and the dissection of shoots. Abundance of ectophagous insects was not reduced by rust infection, and aphids as well as several beetle species were more abundant on systemically infected plants. Preference of endophagous insects differed between species: larvae of Apion weevils were more abundant in infected shoots, whereas Melanagromyza aeneoventris, Urophora cardui, all of them oligophagous, and some leaf miners preferred uninfected plants. In dual‐choice feeding tests, larvae of the oligophagous chrysomelid beetle Cassida rubiginosa were more likely to feed on leaf segments of uninfected thistles. Enhancement of rust infection rate by simulated herbivory was analysed. Thistle leaves were perforated and infection rate was recorded after 2 weeks under natural Puccinia punctiformis spore concentrations. Numbers of uredosori were significantly higher in perforated leaves. Artificial inoculation resulted in an even greater increase in uredosori, both in perforated and unperforated thistles. As the majority of ectophagous and endophagous insects did not discriminate between systemically infected and uninfected thistles, herbivore damage together with infection with Puccinia punctiformis can be expected to increase stress on creeping thistle when used in biological control of the weed. Insects may not only affect plant growth by herbivory but may also increase the susceptibility of healthy thistles to local rust infection by wounding of leaves.

Effect of rust infection on purine catabolism enzyme levels in wheat leaves

Variations in purine catabolism enzymes (xanthine oxidase, uricase and allantoinase) in wheat ( Triticum aestivum) leaves were determined during compatible and incompatible interactions with a local isolate of Puccinia recondita f.sp. tritici. The cultivars Thatcher, Mentana and Leopardo as well as isolines with resistance (Lr) genes in a Thatcher background were employed. The level of xanthine oxidase enhancement was correlated with the three different infection stages: (i) from the beginning to the end of mesophyll colonization by intercellular mycelium (1-4 days post-inoculation); (ii) subepidermal structure (flecks) differentiation (5-7 days post-inoculation); and (iii) maturation of uredospore-producing uredinia (7-11 days post-inoculation). Early and consistent enhancement in xanthine oxidase was detected only during incompatible interactions whereas late enhancements were only detected in the highly compatible ones. In contrast to xanthine oxidase, uricase activity did not change early after infection, whether compatible or incompatible interactions were involved. Uricase was mostly stimulated in the compatible interactions during fungal structure differentiation (stromatic structure and uredinia) and during the same period in moderately incompatible interactions showing macroscopic necrotic symptoms but not in highly incompatible ones (pseudo-immune responses). According to previous results, allantoinase activity was absent in healthy wheat leaves. In rust-infected leaves allantoinase was evident starting from 7 days post-inoculation at the beginning of uredospore differentiation and the values reached corresponded to the level found in germinating uredospore suggesting that the fungal enzyme was being measured. Allantoinase was not detectable in rust-infected leaves 1-4 days post-inoculation with the assay method used and was hardly detectable 5-6 days postinoculation when the activity level in mycelium, calculated on the basis of chitin content, accounted for about one-third of that found during uredospore differentiation. The results obtained indicate that purine catabolism is involved during wheat leaf rust infection. Particular attention was given to the possible role of xanthine oxidase enhancement during the hypersensitive response in relation to the stage of the infection process it took place as well as the duration and intensity reached. The in vivo inhibition of host xanthine oxidase following application of allopurinol by root absorption in concentrations which did not inhibit fungal growth resulted in some inhibition of the hypersensitive response. Therefore, it was concluded that during wheat leaf rust infection, xanthine oxidase is probably responsible, at least in part, for host cell damage associated with hypersensitivity by mechanism/s possibly involving release of toxic amounts of superoxide.

Effect of Rust Infection on Cell Walls of Barley and Wheat; Immunocytochemistry Using Anti‐Barley Thionin as a Probe

AbstractPolyclonal antiserum prepared against barley cell wall thionin was used to localize and quantitate immunoreactive material on the cellular level in healthy and rust‐infected leaves of barley and wheat. Three types of sites were used for the immunocytochemical analysis: as control sites, mesophyll cell walls were selected in uninoculated leaves, and in leaves that were inoculated with rust but where the sites were not in contact with the pathogen: these were compared with mesophyll cell walls that were in contact with intercellular rust hyphae in inoculated leaves.Similar amounts of cell wall thionin were detected in all 3 barley cultivars before inoculation. At sites where intercellular hyphae of Puccinia hordei had made contact with mesophyll cell walls, less thionin was found in the compatible host cv. Larker, but in incompatible hosts (cvs. Gold and Bolivia) the thionin concentration did not differ from that of the controls.Two cultivars of wheat were studied with respect to immunoreactive material in their mesophyll cell walls, the universal rust suscept cv. Little Club and the highly rust‐resistant cv. Khapli. Before inoculation, leaves of cv. Khapli contained about twice the amount of immunoreactive material in mesophyll cell walls than those of cv. Little Club. This relation was unchanged in walls that had made contact with P. graminis tritici, but in non‐contacted walls of infected cv. Little Club leavest, he concentration of this material had risen to levels typical for those of cv. Khapli. Tests for immunoreactive material with pre‐embedding cytochemistry yielded negative results, indicating that it is not exposed on the surface of mesophyll walls in barley and wheat.

Effect of rust infection on levels of uricase, allantoinase and ureides in susceptible and hypersensitive bean leaves

The enzymatic activities involved in two sequential steps of purine catabolism and ureide biosynthesis, i.e. uricase, catalase and allantoinase, were determined in susceptible and hypersensitive bean leaf tissue after infection with Uromyces phaseoli. Uricase increased to approx. two times more than the control value 20–22 h after inoculation of the hypersensitive cv. K.W. 765 (reaction grade 2 ++) close to pathogen penetration and first haustoria formation and, 1 day later, in the susceptible cvs Golden Gate Wax, Pinto 111 (reaction grade 6) and in the hypersensitive cv. K.W. 814 (reaction grade 1). Afterwards, the highest increases in uricase activity (up to 10 times the control), mainly localized in fractions of leaf homogenate sedimenting at 2000 g and 15000 g , were detected in c.v. K.W. 765 during lesion development, indicating that a peroxisome-associated enzyme was involved. Lower increases (up to two to three times the control) were observed in the susceptible cultivars during stroma differentiation (flecks) and uredospore formation. Catalase linked to the particulate fractions increased in susceptible cultivars to the same extent as uricase from 2 to 6 days after inoculation. Also in cv. K.W. 765 it increased during lesion development, but very much less than uricase, with the consequence that a possible toxic action, due to unscavenged H 2O 2 production, could arise during hypersensitivity expression. An enhancement of allantoinase two or three times the control values during stroma differentiation was detected in susceptible cultivars. By contrast, allantoinase activity was unchanged during local lesion formation in cv. K.W. 765, indicating that the activation of this enzyme is specifically involved during the establishment of a biotrophic relationship between Phaseolus vulgaris and Uromyces phaseoli. In the susceptible cultivar, an increase in allantoic acid during the late stages of infection (uredospores differentiation) was observed. Both allantoin and allantoic acid were enhanced during lesion development in the hypersensitive cultivar. The results are consistent with the interpretation that the enhanced purine catabolism in rust-infected bean leaves is connected both to a nutritional benefit for the parasite in the compatible relationship, and to a toxic effect for the host in the incompatible one.

Effect of rust infection on galactolipids and galactolipid fatty acids of vicia faba chloroplasts

Galactolipid content and galactolipid fatty acid composition of chloroplasts isolated from healthy and rust-affected Vicia faba leaves were determined. Rust infection induced a general decrease in monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) from 2 to 14 days after inoculation. The drop in both galactolipids was particularly marked at 8, 10 and 14 days after inoculation. The level of unsaturation and the 18:3 to 18:2 ratio of MGDG fatty acids were slightly reduced at advanced stages of the disease, while in DGDG the decrease of both parameters was observed only at 2 days after inoculation.

The Impact of a Pathogen (Puccinia Lagenophorae) on Populations of Groundsel (Senecio Vulgaris) Overwintering in the Field: II. Reproduction

SUMMARY (1) Reproduction during the spring was studied in monocultures of groundsel (Senecio vulgaris L.) overwintered in the field. In the autumn, populations had been either inoculated with a fungal pathogen (Puccinia lagenophorae), which caused rust disease, or left as controls. The effects of rust infection were examined in relation to status within a hierarchical population (assessed by sub-classes based on shoot dry weights). (2) In control populations, the first capitulum buds were produced in late February. The onset of flowering became progressively delayed as status within the hierarchy declined. In all sub-classes of the population, rust infection during the previous autumn delayed flowering in the spring by 1-2 weeks. (3) The percentage of plants within a sub-class that were reproductive (bore buds or capitula) in March and April declined as status in the hierarchy decreased. In classes of comparable status, fewer plants flowered in inoculated than in control populations. (4) In April, sub-classes with low mean dry weights in both populations produced fewer buds and mature capitula. The number of florets per capitulum were also decreased in lower status classes. Rust inhibited all measured components of reproduction in all classes. (5) During May, many large control plants senesced and their reproductive output declined. Thus, most sub-classes of control populations produced a similar number of florets. In contrast, vegetative growth in inoculated populations continued and all measures of reproduction were far greater in the class of highest status than in any other. There was a seven-fold increase in the contribution of this class to floret production (70%) relative to its frequency in the original population. In control populations, there was no more than a two-fold difference between floret production and frequency in the parent population. (6) Infection resulted in no significant change in the percentage of florets that developed into seed or in the viability of seed. (7) Over the duration of this experiment, the potential seed production of control populations (calculated from capitulum production, florets per capitulum and percentage seed set) was >460 000 seeds m-2. Populations that had been rust-infected in the autumn potentially produced 183 000 seeds m-2, a reduction of >60% compared

Effect of rust infection on rates of photochemical polyphenol oxidation and latent polyphenol oxidase activity of Vicia faba chloroplast membranes

Changes in (i) the rate of light-dependent polyphenol oxidation (via the non-cyclic electron transport pathway) and (ii) the activity of latent membrane-bound polyphenol oxidase (PPO) (measured in the dark) were determined following infection with the rust fungus Uromyces fabae . The rate of photochemical polyphenol oxidation was consistently suppressed in chloroplast membranes isolated from infected leaves, relative to their healthy counterparts. This decrease seemed to be due to the block in the non-cyclic electron transport pathway that we described earlier for the photoreduction of NADP. This conclusion was supported by the finding that rust infection effected a reduction in the rate of the photo-oxidation of both water (NADP as acceptor) and dihydroxyphenylalanine (DOPA) (O 2 as acceptor). In contrast to light-dependent oxidation, enzyme-mediated polyphenol oxidation [assayed in the dark in either the absence or presence of sodium dodecyl sulfate (SDS)] was elevated in chloroplasts from infected leaves. In this respect, latent membrane-bound chloroplast PPO from Vicia faba resembled its soluble active counterpart from other plants.

Some effects of rust infection and moisture stress on growth, diffusive resistance and distribution pattern of labelled assimilates in sunflower

Greenhouse experiments, where sunflower plants (cv. Peredovic) were inoculated with Puccinia helianthi at the vegetative stage of plant growth, showed that the effect of rust on growth parameters varied according to the moisture stress to which plants were subjected. Rust infection caused a marked reduction in the diffusive resistance of leaves in darkness. However, the diffusive resistance in light of leaves not stressed or subjected to mild moisture stress was unaffected by rust infection. In uninfected plants subjected to moderate moisture stress, the diffusive resistance in light increased markedly, whereas in rust-infected leaves it remained the same as in leaves not stressed or subjected to mild moisture stress. Carbon-14 uptake by the first pair of true leaves of non-stressed plants or those subjected to mild moisture stress was unaffected by a low level of rust infection (9% disease rating). Carbon-14 uptake by uninfected leaves was reduced when they were subjected to moderate moisture stress. Rust infection and moderate moisture stress caused a reduction in the rate of translocation of labelled assimilate from leaves fed with 14CO2 and also altered the distribution pattern of labelled translocate to various sinks.

Effects of simulated rust epidemics on the growth and yield of sunflower

Oil yield losses in sunflower (cv. Peredovic) caused by rust infection (Puccinia helianthi) were greatly influenced by the growth stage of the plant when infection occurred and by the intensity of infection. Simulated epidemics produced under greenhouse conditions, where plants were first inoculated at the vegetative, budding, anthesis or seed development stages of growth and thereafter at 10 day intervals, resulted in reductions in oil yield of 85, 73, 38 and 13% respectively relative to those in uninoculated controls. In contrast, plants inoculated once only at each of these growth stages showed reductions in 011 yield of 13, 42, 35 and 10% respectively. When plants were inoculated at the vegetative stage and thereafter at 10, 20 and 40 day intervals, the reductions in oil yield were 85, 79 and 64% respectively relative to uninoculated controls. The reduction in oil yield of infected plants was caused by a reduction in the number of seeds produced per head, the weight of individual seeds and the percentage oil content of seeds. The effects of rust infection on other parameters showed similar trends to that on oil yield.

Fungicides for control of poplar leaf rust and effects of control on growth ofPopulus nigracv. ‘Sempervirens’ andP. × euramericanacv. ‘I-214’

Abstract Infection by Melampsora larici-populina Klebahn. on Populus nigra L. cv. ‘Sempervirens’ and P. × euramericana (Dode) Guinier cv. ‘I-214’, grown for one season from cuttings, was controlled by the fungicides: ‘Bas 31703F’ (0.15%), ‘Cuprox with Calirus’ (0.1%, 0.05%), ‘Thiram with Actidione’ (0.2% 25 ppm), ‘Thiram with Calirus’ (0.08%, 0.05%), ‘Cuprox’ (0.2%), ‘Plantvax 2E’ (0.45%), ‘Melprex’ (0.1%), ‘Polyram combi with Calixin’ (0.16%, 0.05%), ‘Bordeaux’ (2/2/50), ‘Citcop 4E’ (0.4%), and ‘Thiram with nickel sulphate’ (0.12%, 0.10%), when applied at 14- and 21-day intervals. ‘Thiram’ (0.2%) and ‘Dichlone’ (0.10%) were less effective for rust control. The effect of rust infection was greatest upon the root system, and the percentage reduction in diameter growth was greater than height. Root and shoot growth were proportional to the level of rust control through use of fungicides.

Effect of a rust infection on photophosphorylation by isolated chloroplasts

The effect of rust infection on photophosphorylation was determined with chloroplasts isolated from Vicia faba leaves. From the period of extensive haustorial penetration (2 days after inoculation) to the onset of uredospore differentiation (7 days after inoculation), noncyclic photophosphorylation with NADP or ferricyanide as acceptor was inhibited, whereas cyclic photophosphorylation catalyzed by either ferredoxin or phenazine methosulfate was less affected. Evidence is presented that the suppression of ATP formation in noncyclic photophosphorylation induced by the parasite was mainly due to an inhibition of electron transport from water to NADP or ferricyanide.

Effect of rust infection on marquis wheat grain proteins

Rust infected common (bread) wheat (cv. Marquis) lacked one of the low molecular weight glutenin components that was present in the healthy sample of the same variety. This could explain the decrease in gluten content and sedimentation value that resulted from the rust infection. Amino acid analyses showed that the flour protein from the rusted sample contained more of the basic amino acids and less glutamic acid and proline. Rust infection did not affect the polyacrylamide gel electrophoretic patterns.

The effect of rust infection on DNA, RNA, and protein in nuclei of Khapli wheat leaves

The effects were determined of infection with Race 15B of the stem rust fungus on the levels of nuclear DNA (Feulgen), RNA (azure B), histone (fast green pH 8.1), and total protein (fast green pH 2.0) and on the size of the nuclei in the mesophyll cells of the primary leaf of Khapli wheat (rust reaction type 1). Nuclear size, RNA, and total protein content increased and histone content decreased by 3 days after inoculation. DNA content decreased from 4 days after inoculation. These results for the resistant variety Khapli are similar to those reported earlier for the susceptible variety, Little Club, but the observed changes occur more rapidly after inoculation than they do in Little Club.

Effect of Rust Infection on Oxidative Phosphorylation of Wheat Leaves

WE have already reported1,2 that the rate of consumption of oxygen by wheat leaves infected with stem rust fungus is not augmented by treatment with 2,4-dinitrophenol, in contrast with the great respiratory increase observed in healthy leaf tissue after treatment with dinitrophenol.

Effects of Rust Infection on the Carbohydrate Metabolism of Wheat Seedlings

In the course of studies on the nature of resistance of plants to disease, experiments were performed to determine the effect of stem rust (Puccinia graminis Pers. f. sp. tritici Erikss. and Henn., race 34) infection on the distribution of the carbon-14 of photosynthetically fixed carbon-14 dioxide among the sugars in the wheat varieties Gabo 54 and Little Club. These varieties are resistant (reaction type 1) and susceptible (reaction type 4), respectively, to race 34 of the pathogen.