Concepts and Direction of Induced Systemic Resistance in Plants and its Application

Resistance to plant disease is often specific and metabolites and receptors contributing to this specificity may have specific structures. However, simple, structurally-unrelated compounds induce systemic resistance in unrelated plants to diverse pathogens including fungi, bacteria and viruses. Both resistance and induced systemic resistance (ISR) are associated with the rapid accumulation of the same structurally unrelated putative defense compounds that have diverse functions. It has been suggested that cultivar (race)-specific resistance is initiated by the specific interaction of a pathogen product (or pathogen induced product) and a plant receptor. However, restricted infection by pathogens can result in ISR and many different compounds can cause ISR. It is thus evident that there are both specific and non-specific routes to the master switch for ISR and there may be more than one master switch. Are reactive oxygen species and free radicals regulating the master switch(es) via both routes? It is also evident there are many switches, other than the master switch. Adding to the complexity of resistance and ISR are the observations that different compounds and pathways may mediate different biochemical resistances. Activation of one of the pathways may antagonize or enhance the activation or effectiveness of another. The review will address these complexities and questions and propose directions of research which require high priority. Factors which encourage and suppress the application of ISR in agriculture will also be addressed.     

Impaired female fertility in tubulointerstitial antigen-like 1-deficient mice

Tubulointerstitial nephritis antigen-like 1 (Tinagl1, also known as adrenocortical zonation factor 1 [AZ-1] or lipocalin 7) is a matricellular protein. Previously, we demonstrated that Tinagl1 expression was restricted to extraembryonic regions during the postimplantation period and detected marked expression in mouse Reichert’s membranes. In uteri, Tinagl1 is markedly expressed in the decidual endometrium during the postimplantation period, suggesting that it plays a physical and physiological role in embryo development and/or decidualization of the uterine endometrium during pregnancy. In the present study, in order to determine the role of Tinagl1 during embryonic development and pregnancy, we generated Tinagl1-deficient mice. Although Tinagl1^–/– embryos were not lethal during development to term, homologous matings of Tinagl1^–/– females and Tinagl1^–/– males showed impaired fertility during pregnancy, including failure to carry pregnancy to term and perinatal lethality. To examine ovarian function, ovulation was induced with equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG); the number of ovulated oocytes did not differ between Tinagl1^–/– and Tinagl1^flox/flox. In vitro fertilization followed by embryo culture also demonstrated the normal developmental potential of Tinagl1-null embryos during the preimplantation period. Our results demonstrate that Tinagl1 deficiency affects female mice and results in subfertility phenotypes, and they suggest that although the potential of Tinagl1^–/– oocytes is normal, Tinagl1 is related to fertility in adult females but is not essential for either fertilization or preimplantation development in vitro.     

Maize defence mechanisms against the European corn borer,Ostrinia nubilalis Hübner (Lepidoptera: Crambidae)

Maize is arguably the most widely grown crop in the world, but it is often associated with one of its major insect pests, the European corn borer (ECB). The damage caused by this species to maize production is generally variable, but in many cases it is economically significant. This review paper provides an overview of the research findings on the natural plant defence mechanisms against ECB larvae published till now. What is resistance and how it is achieved, what is the chemical response of maize plants to insect feeding and how tolerance can be increased. A short introduction in breeding for resistance and a discussion if the mentioned traits can be used in conventional breeding in order to create maize hybrids less affected by ECB are given.     

The Characterization of Heavy Metals in the Grapevine (Vitis vinifera) Cultivar Rkatsiteli and Wild Blackberry (Rubus fruticosus) from East Serbia by ICP-OES and BAFs

Inductively coupled plasma optical emission spectroscopy, in combination with calculation of various biological factors, was used in this study not only for a simple illustration of the present status of some essential and non-essential metals such as copper (Cu), zinc (Zn), nickel (Ni), lead (Pb), arsenic (As), and cadmium (Cd) in the grapevine cultivar Rkatsiteli and wild blackberry from East Serbia but also for the estimation of plant bioaccumulation potentials. Great majority of detected metal concentrations were in normal ranges except in few cases: Zn concentrations were at the level of deficiency in almost all plant parts, and some Cu and As concentrations were at the levels that could be considered phytotoxic. Biological accumulation factors provided very informative data on metal accumulation and translocation in both plants and pointed to low accumulation rates of metals except in the case of Cu, Zn, and As in some wild blackberry tissues.     

Evidence for genetic diversity of Toxoplasma gondii in selected intermediate hosts in Serbia

To contribute to the insight into the worldwide population structure of Toxoplasma gondii, we genetically characterized a total of eight strains isolated from intermediate hosts including humans, sheep and pigeons in Serbia. Although parasite DNA was detected in 28.2% (60/213) of the human samples from 162 patients serologically suspected of active toxoplasmosis, as well as in 5/7 seropositive pigeons and in 2/12 seropositive sheep examined, multilocus PCR-RFLP genotyping, using SAG1, 5′SAG2, 3′SAG2, GRA6, 5′GRA7 and 3′GRA7 as markers, was successful in only four human isolates (of which one was isolated from both the bronchoalveolar lavage fluid and blood samples of a single patient), one sheep and three pigeons. Of the eight isolates, five were type II (62.5%), one was type III, one was atypical, and one had a type I allele at GRA6 as the single locus genotyped. Although type II, as elsewhere in Europe, predominated, these results may suggest a higher genetic diversity of T. gondii in Serbia, reflecting local environmental contamination and also the geographical position of the country in South-East Europe.     

Comparison of bacterial culture, polymerase chain reaction, and a mix-enzyme-linked immunosorbent assay for the detection of Salmonella status in grow-to-finish pigs in western Canada with a Bayesian approach

Among grow-to-finish pigs from 10 herds in Alberta and Saskatchewan, 23 (16%) of 144 fecal samples were culture-positive and 40 (28%) of 144 pigs were seropositive for Salmonella. With a Bayesian model specifying dependence between the 2 tests, the sensitivity (Se) of culture and real-time polymerase chain reaction (RT-PCR) was 79% to 86%, depending on the cut-off value for the enzyme-linked immunosorbent assay (ELISA). Culture specificity (Sp) was assumed to be 100%; RT-PCR Sp was found to be 94%. The ELISA Se was 76% and 51% at optical density cut-off values ≥ 20% and ≥ 40%, respectively; the Sp was 94% at each cut-off value. The model showed some sensitivity to ELISA prior information, the ELISA Se being approximately 8% lower when informative prior information was specified in the model. When there was no adjustment for dependence between culture and RT-PCR, the posterior estimates for both culture and RT-PCR Se were 11% higher than with the conditional-dependence model and had considerably narrower probability intervals, which suggests that correlation between culture and PCR is important and should be adjusted for in future studies.     

Proportion of circulating chicken heterophils and CXCLi2 expression in response to Salmonella enteritidis are affected by genetic line and immune modulating diet

Genetic line and diet affect chicken heterophil activity and gene expression, and the combination of these factors can enhance disease resistance. This study evaluated the effects of immune modulating diets on heterophil/lymphocyte (H/L) ratio and heterophil chemokine expression in distinct genetic lines. Fayoumi and Leghorn chickens were fed a basal diet or immune modulating diets enhanced with β-glucans, ascorbic acid, or corticosterone. H/L ratios and heterophil gene expression in response to in vitro stimulation with Salmonella enteritidis (SE) were evaluated on days 1, 3, 7, and 21 of diet treatment. The stress-mimicking corticosterone diet influenced H/L ratio in the Leghorn line, but not the Fayoumi line, suggesting resistance to stress-induced immunosuppression in the Fayoumi line. Leghorn line H/L ratios were increased on days 1 and 3 of corticosterone diet treatment, but not days 7 or 21. Expression of CXCLi2 by SE stimulated heterophils was higher in the Leghorn line, suggesting that Leghorns rely more heavily on inflammatory response than do Fayoumis. Corticosterone diet was associated with reduced CXCLi2 expression in heterophils from both lines. Dietary β-glucan or ascorbic acid did not affect H/L ratio or CXCLi2 expression, suggesting that benefits of these immunomodulators may not be evident in healthy birds.     

Intratesticular benign peripheral nerve sheath tumour in a ferret (Mustela putorius furo)

A domestic ferret was submitted for sterilisation because of right testis enlargement. Oestradiol and cortisol concentrations were within normal physiological ranges, but testosterone was below and progesterone above normal. Microscopically, the right testis, with the exception of a small part of the epididymis, was replaced with neoplastic tissue. The tumour was composed of streams and bundles of closely packed spindle to ovoid cells forming whorls around collagen and capillaries, and separated by a collagenous matrix. In some areas, cells were loosely arranged and separated by a pale myxomatous matrix. The left testis showed atrophy. The majority of neoplastic cells expressed vimentin and S-100 protein, while expression of collagen IV was moderate and there was no expression of glial fibrillary acid protein. On the basis of macroscopical and histopathological findings, and supported by immunohistochemical reactivity, the diagnosis of benign peripheral nerve sheath tumour was made. This is the first report of benign peripheral nerve sheath tumour in ferret testis.