Characterization of wild plum (<Emphasis Type="Italic">Ximenia americana</Emphasis> L. var. <Emphasis Type="Italic">americana</Emphasis>; Olacaceae) fruit growing at Tepexi de Rodríguez,Puebla, Mexico

As a country, Mexico presents an especially wide range of fruit germplasm diversity. Tepexi de Rodríguez, Puebla, Mexico, belongs to The Tehuacán-Cuicatlán Valley, which is an arid zone recognized to have a flora diversity. In that place, wild plum (Ximenia americana L. var. americana; Olacaceae), locally named “tihuixocote” grows mainly in backyards, the fruit of this species is appreciated by native people due to its taste, which is reported to be a mixture between sweet and sour. Fruit from 15 trees were characterized by measuring bio-physical and bio-chemical parameters, including weight, diameter (equatorial and polar), relationship equatorial/polar diameters, total sugar, soluble solid content and phenolic compounds. The results of this study indicate variability for these various wild plum fruit characteristics among trees growing in a reduced territorial space.     

Reaction of potato varieties toPotato mop-top virus infection in the andes

The unexpected detection ofPotato mop-top virus (PMTV) in potatoes growing at several locations in the U.S.A. and Canada in 2002 has led to the realization that this soil-borne virus may be widespread throughout the potato-producing regions of both countries. A lack of information concerning the response of U.S. cultivars to PMTV infection caused us to examine the effects of PMTV on field-grown plants at three locations in the Peruvian Andes where the virus and its fungal vector,Spongospora subterranea, are endemic. All 21 U.S. cultivars tested proved susceptible to PMTV infection, especially at La Victoria where the overall incidence of both PMTV and powdery scab was high. Symptom expression in the foliage proved to be an unreliable indicator of virus infection, and thus, more reliable serological (NCM-ELISA) and nucleic acid-based techniques (NASH and RT-PCR) were used to monitor tuber tissue for the presence of PMTV. As much as 25% of field-grown tubers of cvs Kennebec, Monona, and Norland were infected with PMTV, but no correlation between virus infection and either the incidence or severity of powdery scab for any variety was apparent. Although PMTV infection did not result in the appearance of spraing or other internal necrotic reactions resembling those reported from many North American and European locations, a disproportionate proportion of infected tubers did exhibit a reticulate surface cracking. In hydroponic culture, the proportion of cracked tubers increased dramatically when the nutrient solution was seeded with virus-infestedS. subterranea. Comparatively few tubers of cvs Monona and Russet Burbank exhibited this surface cracking, suggesting that these two varieties may be somewhat tolerant to PMTV infection.     

Coupling proton transfer reaction-mass spectrometry with linear discriminant analysis: a case study

Proton transfer reaction-mass spectrometry (PTR-MS) measurements on single intact strawberry fruits were combined with an appropriate data analysis based on compression of spectrometric data followed by class modeling. In a first experiment 8 of 9 different strawberry varieties measured on the third to fourth day after harvest could be successfully distinguished by linear discriminant analysis (LDA) on PTR-MS spectra compressed by discriminant partial least squares (dPLS). In a second experiment two varieties were investigated as to whether different growing conditions (open field, tunnel), location, and/or harvesting time can affect the proposed classification method. Internal cross-validation gives 27 successes of 28 tests for the 9 varieties experiment and 100% for the 2 clones experiment (30 samples). For one clone, present in both experiments, the models developed for one experiment were successfully tested with the homogeneous independent data of the other with success rates of 100% (3 of 3) and 93% (14 of 15), respectively. This is an indication that the proposed combination of PTR-MS with discriminant analysis and class modeling provides a new and valuable tool for product classification in agroindustrial applications.     

Performance and water requirement of young olives (Olea europaea L.) in the harsh environment of Kuwait

In the harsh environmental conditions of Kuwait, plants are frequently exposed to high temperatures, low relative humidity and drought. Because water resources available for agriculture are limited, an efficient irrigation strategy is vital for sustainable olive production. In view of these facts, a study to determine the behavior and water requirement of young olive plants under Kuwait's environmental conditions was carried out. The investigation included five cultivars (cvs. Arbequina, Barnea, Coratina, Koroneiki and UC13A6) and three levels of irrigation (50, 75 and 100% of ETc) with brackish water (ECe 5.0 dS m^?1). One-year-old grafted plants were used in this study. With the exception of UC13A6, the cultivars showed good adaptation to the harsh weather conditions in Kuwait and to brackish water irrigation during the first 18 months after the beginning of the irrigation treatments. Indeed, they showed good height and shoot growth, with cultivars Barnea, Arbequina and Coratina showing the highest values. Cultivar Barnea was the most vigorous variety under Kuwait's environmental conditions. Vegetative growth in these varieties was not significantly reduced in the 50% ETc treatment. This indicates huge opportunities to improve the water-use-efficiency through further investigations aimed at optimizing the amount of water supplied with irrigation.     

Effects of ethylene and 1-methylcyclopropene (1-MCP) on gene expression and activity profile of alpha-1,4-glucan-phosphorylase during banana ripening

Starch phosphorylases are enzymes that can use starch as substrate, and they are supposed to act in both in starch synthesis and degradation. This paper reports the effects of ethylene and 1-methylcyclopropene (1-MCP) on the degradation of starch and phosphorylase activity and gene expression. The results indicate that phosphorylase activity is induced during ripening and that it is associated with the onset of starch degradation. The regulation of banana phosphorylase activity is mainly dependent on gene expression, and the absence of ethylene perception by 1-MCP had a positive effect. However, this effect can be precluded by increased levels of ethylene, both autocatalytic and exogenous.     

Morphological and molecular characterization of different Echinochloa spp. and Oryza sativa populations

Echinochloa P. Beauv. is an important genus because many of its species are weeds infesting most paddy fields, which can reduce the rice grain production by up to 80%. A controversy exists about the taxonomy of the genus due to the high level of morphological variations found in these species. Cyhalofop-butyl, an aryloxyphenoxy-propionate herbicide, is used to control Echinochloa spp. in paddy fields, although differences in susceptibility were found between different Echinochloa species. E. colona was highly susceptible [ED50= 34 g of active ingredient (ai) ha(-1)]; very similar results were obtained with the remaining species. By contrast, E. oryzicola (170 g of ai ha(-1)) was less sensitive, with the herbicide symptoms appearing later. Because of this differential susceptibility, morphological and molecular studies were carried out. A morphological study, using 21 characters both quantitative and qualitative of spikelets and seedlings, was capable of clearly distinguishing closely related E. crus-galli plants (two populations), E. muricata and E. crus-pavonis, and E. oryzicola, E. utilis, and E. colona species. The resolution of Echinochloa species at the molecular level, based on RAPD analyses, was fairly consistent with morphological analysis results. Among the 60 primers screened, 21 primers exhibited polymorphic bands and produced a total of 136 RAPD markers. Of all the amplified fragments, 90 were found to be polymorphic. E. oryzicola and E. colona were clearly separated, and the RAPD analyses showed that both E. crus-galli populations were 100% related and 51% related to E. utilis, whereas E. crus-pavonis and E. muricata (73% similarity) appeared as being clearly separated from this group.     

Natural and synthetic antioxidant additives for improving the performance of new biolubricant formulations

Knowledge of the oxidative stability of vegetable oils for lubricant applications is a key point, because vegetable oil oxidation potential is the main disadvantage for its use as a lubricant. Oil degradation after an oxidation process can seriously affect its lubricating function and increase wear. In this work, two different methods for evaluating the oxidation stability of lubricating vegetable oils, the oxidation onset temperature, characterized through DSC measurements (ASTM E 2009-08), and the pressure drop in the oxygen pressure vessel (ASTM D 942-02), have been used. Additionally, thermogravimetric analysis and FTIR studies have also been carried out. High-oleic sunflower (HOSO) and castor (CO) oils were selected and blended with natural ((+)-α-tocopherol (TCP), propyl gallate (PG), l-ascorbic acid 6-palmitate (AP)) or synthetic antioxidants (4,4'-methylenebis(2,6-di-tert-butylphenol) (MBP)), with the aim of formulating biodegradable vegetable-based lubricants according to REACH regulation. (1) The results showed that the most effective biodegradable antioxidant is PG, comparable to MBP, whereas lower effectiveness was obtained for TCP and AP. In relation to the methods tested, DSC measurements achieve accurate data more quickly for evaluating the oxidation stability of these basestocks, showing a linear correlation with the traditional method based on the oxygen bomb test. The empirical equation obtained depends on the mechanism involved in the antioxidant activity.     

Collaborative study of the determination of boric acid in caviar by emission spectroscopy.

Caviar samples were spiked at the 0.1 and 0.2% levels and digested with nitric acid in a closed Teflon-lined digestion vessel to prevent volatility losses. The boron was complexed with 2-ethyl-1,3-hexanediol and extracted into methylisobulty ketone. The emission of the boron oxide band was measured in a nitrous oxidehydrogen flame. The mean recoveries at the 0.1 and 0.2% levels for 6 collaborators were 95.7 and 97.1%, respectively.     

Egg detection in females of the polyphagous predator <Emphasis Type="Italic">Macrolophus pygmaeus</Emphasis> (Heteroptera: Miridae) by serological techniques

Macrolophus pygmaeus is a polyphagous mirid bug native to the Mediterranean area where it is widely used in the biological control of whiteflies and other pests in vegetable crops. To assess the presence of eggs in females is important in order to optimize predator release strategies, as well as their mass rearing. This study shows an alternative to the traditional procedures of fertility assessment based on evaluation of newly hatched nymphs. A polyclonal antiserum was produced against M. pygmaeus egg proteins, and an ELISA protocol was developed to determine whether laboratory-reared or field-collected females contained egg proteins (mainly vitellin). When field-collected females were analysed, an 80% contained egg proteins indicating that they were reproductively active. Presence/absence of egg proteins was detected with an error than 1%. Since this ELISA protocol allowed also the detection of egg protein precursors, it was more precise and less time consuming than conventional techniques as abdomen dissection or egg-hatch evaluation in determining egg presence in females.     

Systemic acquired resistance in crop protection: from nature to a chemical approach

Plant natural resistance to potential parasites is regulated by two fundamental mechanisms: the "nonhost" and the "gene-for-gene" resistance, respectively. The latter is relevant when a cultivar resistant (R) gene product recognizes an avirulence gene product in the attacking pathogen and triggers an array of biochemical reactions that halt the pathogen around the site of attempted invasion. To cope with virulent pathogens, plants may benefit by some temporary immunity after a challenge triggering such an array of defense reactions, following a localized necrotizing infection as a possible consequence of a hypersensitive response (HR). This process, mediated by accumulation of endogenous salicylic acid (SA), is called systemic acquired resistance (SAR) and provides resistance, to a certain extent even against unrelated pathogens, such as viruses, bacteria, and fungi, for a relatively long-lasting period. SAR may be more potently activated in plants pretreated with chemical inducers, most of which appear to act as functional analogues of SA. This review summarizes the complex aspects of SAR as a way to prevent crop diseases by activating the plants' own natural defenses. The following outline is taken: (1) introduction through the historical insight of the phenomenon; (2) oxidative burst, which produces high levels of oxygen reactive species in a way similar to the inflammation state in animals and precedes the HR to the pathogen attack; (3) SAR as a coordinate action of several gene products leading to the expression of defenses well beyond the time and space limits of the HR; (4) jasmonic acid (JA) and ethylene as other endogenous factors mediating a different pathway of induced resistance; (5) pathogenesis related proteins (PR proteins) de novo synthesized as specific markers of SAR; (6) exogenous inducers of SAR, which include both synthetic chemicals and natural products; (7) the pathway of signal transduction between sensitization by inducers and PR expression, as inferred by mutageneses, a process that is still, to a large extent, not completely elucidated; (8) prospects and costs; (9) final remarks on the state-of-the-art of the topic reflecting the chemical view of the author, based on the more authoritative ones expressed by the authors of the reviewed papers.