The causal agent of cucurbit powdery mildew in southeastern Spain has been investigated since 1996. Of the 139 single-spore
isolates obtained, all were identified asSphaerotheca fusca. Four physiological races (1, 2, 4 and 5) of the pathogen were detected. During the survey, a population shift ofS. fusca was observed: race 1 was progressively replaced by other races. In addition, race coexistence was observed in several cucurbit
greenhouses. Four host range patterns or pathotypes were distinguished among the isolates ofS. fusca. All isolates were highly aggressive on melon and especially on zucchini cultivars. No clear relationships between races
and pathotypes could be established, although isolates virulent on watermelon were preferentially associated with race 1.
These data show an apparent heterogeneity ofS. fusca populations in southeastern Spain that should be analyzed further.
http://www.phytoparasitica.org posting Aug. 9, 2002. 相似文献
The inoculation of different isolates ofSclerotinia sclerotiorum (Lib.) de at various host sites showed that infection severity differed between sites on the same host, but not between isolates. We suggest that these differences are due to variations in relative humidity between the ambient conditions within the plant canopy rather than to different susceptibilities to infection of the plant organs. 相似文献
The Kemp’s ridley (Lepidochelys kempii) is the world’s most endangered sea turtle species. Predominately nesting at only one beach in Mexico, this species declined to an estimated 300 females in the mid-1980s. Conservation efforts in the United States and Mexico, including a head start programme in southern Texas in which hatchlings were reared in captivity for several months before being released into the wild, resulted in the recovery of this species.
Although genetic data have previously been used to assess the success of the head start programme and dispersal of individual adults, data on immature turtles sampled at foraging areas and adult females sampled at the main nesting beach in Mexico are lacking. Genetic characterization of immature individuals is important for understanding recruitment, survival, and population demography, while genetic data on individuals from Mexico are essential for understanding dispersal and overall genetic diversity in this species.
To address these gaps, mitochondrial DNA data were collected from 106 immature individuals sampled at four different foraging sites in the northern Gulf of Mexico and from 18 nesting females at the primary nesting beach in Mexico.
Two previously unknown mitochondrial DNA haplotypes were discovered among the immature individuals.
Except for these two new haplotypes, the genetic diversity of immature individuals in the northern Gulf of Mexico closely corresponds to that of adults sampled in Mexico, which suggests that much of the diversity within the nesting population can be found among immature animals dispersing to foraging grounds, including locations in the northern Gulf of Mexico.
Continued monitoring of the genetic variation of different life stages of this species across its distribution range will help assess the success of conservation programmes by ensuring the maintenance of genetic diversity and representation of this diversity across the species’ distribution range.
Background: Urinary tract infection (UTI) is a common disease in sows due to intensification of pig production. Despite direct economic losses, UTI prevalence and respective microbial identification are still poorly studied.
Objective: The aims of this study were to identify the causative agents of UTI in sows through MALDI-TOF MS and to characterize their antimicrobial resistance profiles.
Materials and Methods: Urine samples from 300 sows of three herds from São Paulo State (Brazil) were screened for UTI; suggestive samples were submitted to bacterial isolation. Species identification was performed by MALDI-TOF MS and susceptibility profiles were determined using disc diffusion method.
Results: 128 samples suggestive of UTI were analyzed; 48% of the animals presented UTI caused by a single pathogen, while the remaining 52% presented mixed infection. Escherichia coli stood out with the highest frequency among both single and mixed infections. The Gram-positive were exclusively associated with 27% of single infections. The mixed infections were further classified into 49 profiles. The high frequency of multiresistant profiles stood out for most of the studied isolates.
Conclusions: MALDI-TOF MS enabled the identification of rare pathogens related to UTI which may represent higher risk for porcine health, especially considering high frequency of multiresistant profiles. 相似文献
The use of plastic materials for mulching is a very common practice for vegetable crops. Black polyethylene is the most widely used due to its excellent properties and low cost. However, the massive use of these materials supposes an environmental risk. In the last few years, the use of starch-based biodegradable films has been introduced as an alternative to conventional mulches. These materials can be incorporated into the soil at the end of the crop season and undergo biodegradation by soil microorganisms. A 2-year study was conducted to determine the response of a tomato crop to seven mulch materials (polyethylene and biodegradable) in open fields in Central Spain. Biodegradable films underwent early decomposition, but in general remained functional during use and did not affect yield and the fruit quality attributes (total soluble solids, firmness, dry weight, juice content and shape). The temperatures reached under polyethylene films were always higher than under biodegradable films, which could be a disadvantage in certain circumstances, especially in hot climates, although may be advantageous in cool conditions. The use of polyethylene films resulted in the lowest values of soil microbial biomass C and soil organic matter mineralization, probably due to the increase of temperature registered under mulches. The analysis of the marketable yield components indicates that the variability in yield mainly depended on the number of fruits, with mean fruit weight being practically constant in the different treatments and seasons, which suggests the strong varietal character of this parameter. 相似文献
There is an increasing interest in the legume species Medicago truncatula as a model plant for structural and functional genomic studies that can be used to identify agronomically important genes in legumes. Field screening has shown very high levels of resistance to Orobanche crenata in M. truncatula. However, in vitro studies with O. crenata, Orobanche foetida, Orobanche ramosa and Orobanche minor showed useful variation among accessions at early stages of the parasite–host interaction. Significant differences were observed in the levels of germination of O. crenata and O. foetida seeds induced by different accessions of M. truncatula. Only limited germination was observed on accession SA‐4327. All accessions induced little O. ramosa and O. minor germination. Accessions also varied in the number of O. crenata and O. foetida attachments supported, with few developing on accession SA‐27774. The variation observed for induction of germination and of subsequent attachment will be useful to isolating and characterizing genes involved in the early stages of Orobanche–host plant interaction and for the study of the biosynthetic pathways of production for germination stimulants. 相似文献
The aim of this study is to explore the potential use of the information generated by the Spanish traceability program (SIMOGAN) for animal breeding purposes in the Pirenaica beef cattle breed. The traits included in the study were: cold carcass weight (CW, n = 20,010), conformation (CON, n = 15,808), fat cover (FC, n = 13,739) and colour (COL, n = 3477) from the SIMOGAN database; and weaning weight (WW, n = 15,561) from the Breeders Association (CONASPI) database. Posterior marginal estimates of genetic parameters were obtained using Bayesian inference, implemented via a Gibbs sampling scheme. Posterior marginal means of heritabilities were 0.34, 0.28, 0.19, 0.23 and 0.38 for CW, CON, FC, COL and WW, respectively. Moreover, posterior marginal distributions of genetic correlations between CW-CON, CW-WW, CON-FC and FC-WW do not include the zero within the Highest Posterior Density (HPD) at 95%, and their posterior mean estimates were 0.30, 0.54, − 0.35 and 0.23, respectively. These results indicate that there is enough genetic variability for selection in CW, CON, FC, COL and WW. The availability of records is potentially abundant at a very low cost, thus they can be easily included in the selection criteria. Consequences of the current selection criteria (WW) and other possible alternatives are discussed. 相似文献