Nitrogen loading of Eucalyptus globulus seedlings: nutritional dynamics and influence on morphology and root growth potential

New Forests - Achieving successful outplanting of trees on increasingly harsher sites is a global concern. In Chile, for example, new Eucalyptus globulus plantations are being targeted to poorer,...     

A lesion-mimic mutant of wheat with enhanced resistance to leaf rust

A lesion-mimic mutant was obtained from a mutagenic treatment performed with ethyl methanesulfonate on the Argentine bread wheat ( Triticum aestivum ) cultivar Sinvalocho M.A. The HLP (hypersensitive-like phenotype) mutant exhibited tiny, discrete, white lesions in the absence of any pathogen, resembling the typical hypersensitive response (HR). The lesions only became evident once the fifth or sixth leaf emerged, and spread at random along the leaf blades and leaf sheaths of the developing plant, including tissues of the spike. Because the lesion-mimic mutant showed no lesions at the seedling stage, the phenotypes of both the mutant and its mother line were identical at this point. Histochemical studies showed that spontaneous hypersensitive-like lesions in the HLP mutant corresponded to cell death. In leaf-rust ( Puccinia triticina ) infection experiments performed at seedling and adult-plant stages, adult HLP plants showed enhanced resistance to leaf-rust attack compared with plants of Sinvalocho M.A. of comparable developmental stage, suggesting that the HLP mutation may confer increased resistance to the fungus. Because enhanced resistance coincided with the presence of spontaneous HR lesions, activation of HLP plant defence responses appeared to be tightly linked to this phenomenon. Final plant height and yield components in the lesion-mimic mutant did not differ from those of the mother line, indicating that the HLP mutation caused no detrimental pleiotropic effects that significantly affected agronomic performance. These data support the direct use of mutations in disease-resistance breeding.     

An investigation of Salmonella Fluntern illnesses linked to leopard geckos—United States, 2018

Reptile contact can result in zoonotic non‐typhoidal salmonellosis. In April 2018, Oregon Public Health Division contacted CDC about a cluster of four Salmonella serovar Fluntern (SF) illnesses in four states (OR, CA, IA, NY); patients reported contact with geckos, a popular reptile pet. PulseNet, the national molecular subtyping network of food‐borne disease surveillance, subsequently identified additional SF clinical isolates. Twelve cases in 11 states were identified; median age was 5 years (range: <1–58 years). Three patients were hospitalized; no deaths were reported. Of those with exposure information (n = 10), all reported reptile exposure; 9 (90%) specified contact with leopard geckos. No common source of geckos was identified from reported purchase locations. Los Angeles County (LAC) health officials isolated SF from one patient's leopard gecko. Five reptile/gecko isolates were identified from the USDA National Veterinary Services Laboratories (NVSL) from 2015 to 2018. Five countries responded to an Epidemic Intelligence Information System post by PulseNet; reptile isolate sequence data were received from Czech Republic. A clinical case from England was identified through the National Center for Biotechnology Information pathogen detection pipeline; the patient did not report contact with leopard geckos. Whole genome sequencing analysis revealed substantial genetic diversity between clinical and animal isolates; however, gecko and clinical isolates from LAC were highly related (1 allele difference). This investigation linking SF illnesses to leopard geckos highlights an important public health risk from pets. A better understanding of how geckos are distributed by the pet industry in the United States could improve traceability to points of origin and mitigate Salmonella transmission at gecko breeders. Earlier NVSL reports of SF isolates from geckos suggest the risk of human SF infection from geckos is not new. This investigation demonstrates a need to educate gecko breeders, retailers and gecko owners about the continued Salmonella infection risk from pet geckos.     

Genetic differentiation among Atlantic island populations of the brown spiny lobster Panulirus echinatus (Decapoda: Palinuridae)

1. Declines in Panulirus echinatus Smith, 1869 populations along their wide distribution in the Atlantic Ocean have spurred efforts to improve their fisheries management and conservation. In this study, the genetic structure of these populations is reported for the first time.
2. In a survey of 18 species‐specific polymorphic microsatellite markers, 152 individuals were genotyped from five Atlantic oceanic islands, covering most of the insular distribution range of the species. The analyses revealed that P. echinatus is genetically partitioned into two stocks in the Atlantic Ocean. A highly significant genetic structure was observed between north‐east and south‐west Atlantic populations based on fixation index, discriminant analysis of principal components, and structure and barrier analysis.
3. We suggest that the Equatorial Circulation System represents a biophysical barrier that effectively limits migration among Atlantic subtropical gyre systems, as has been described for other species. Other physical and ecological barriers, such as the Mid‐Atlantic Ridge itself, the distance between the eastern and western sides of the Atlantic (Mid‐Atlantic Barrier) and water mass differences, as well as other biological aspects, may also influence larval dispersal and modulate the insular distribution of this species.
4. The results show the existence of two distinct genetic stocks of P. echinatus and have implications for fisheries management in the Atlantic Ocean, including their independent management according to their individual status. The Cabo Verde and the Canarian populations (north‐east Atlantic) showed the lowest level of genetic variability in comparison with the south‐western populations. A combination of factors that have occurred or are occurring in the Canary Islands, such as overfishing and volcanic eruptions, is likely to explain the reduced abundance of this lobster species in the area.

     

Analysis of Quality Protein Changes in Nixtamalized QPM Flours as a Function of the Steeping Time

This study showed the protein changes in Quality Protein Maize (QPM H‐368C) during the traditional nixtamalization process as a function of the steeping time from 0 to 15 hr. Protein content (N × 6.25), pH, protein fractionation, reactive lysine, essential amino acids, and protein digestibility were analyzed to explain the protein quality modifications in nixtamalized corn flours (NQF). The thermoalkaline process increased significantly (P ≤ 0.05) the protein content (5.57 ± 0.86%) in NQF obtained at 3, 5, 7, 9, 11, 13, and 15 hr of steeping time compared with native corn or corn without treatment (NC). The pH values of NQF were not proportional to the steeping time and significantly different (P ≤ 0.05) between them. At 5 hr critical steeping time, the total lysine and reactive lysine content decreased severely (36 and 32%, respectively) with statistical differences (P ≤ 0.05) compared with NC. On the other hand, the tryptophan content decreased significantly (P ≤ 0.05) at steeping times of 5–15 hr (38.70 ± 6.7%) compared with NC. The changes in the lysine and tryptophan content were not proportional to the steeping time. The protein recovery in the albumin and globulin fraction diminished (P ≤ 0.05) with respect to raw corn. The protein recovery for γ‐zeins, glutelin‐like proteins, glutelins, and residue increased. A significant (P ≤ 0.05) decrease was found in the essential amino acids in NQF with 3–7 hr of steeping time compared with NC. Equally important was the reduction in protein digestibility observed in NQF steeped at long steeping times (11–15 hr) with significant (P ≤ 0.05) differences compared with NC. The protein solubility distribution along the steeping step and the essential amino acids location, specifically lysine in corn kernel, could explain partially the protein quality changes observed in this research. Finally, these results contribute to reconciling discrepancies associated with the protein quality modifications in nixtamalized corn reported previously in literature.     

Genetic diversity in the parental lines and heterosis of the tropical rice hybrids

Genetic diversity within and between the maintainer (B) and restorer (R) lines used in hybrid breeding programs of the Philippine was investigated with information from analysis of pedigree record, quantitative traits and SSR assays. Mean coefficients of coancestry were calculated as 0.11 within R lines, 0.27 within B lines, and 0.04 between R and B lines, indicating greater diversity among R lines than among B lines, and the significant divergence between B and R lines. These results are consistent with those obtained from quantitative trait analysis and SSR marker assays. Relative gene diversity for 37 random SSR markers averaged 0.20 within B lines,0.28 within R lines, and 0.52 between two groups of lines. There were no consistent associations among various genetic diversity measures. Random sets of SSR marker and pedigree based diversity measures had no significant correlation with mid-parent heterosis for grain yield and biomass, indicating that prediction of heterosis for complex traits based on these two genetic diversity estimates is difficult. This revised version was published online in August 2006 with corrections to the Cover Date.     

Evaluation of proline analysis and chlorophyll fluorescence quenching measurements as drought tolerance indicators in durum wheat (Triticum turgidum L. var. durum)

Summary The possibility of using proline accumulation and fluorescence inhibition as predictive tests for drought tolerance in durum wheat has been investigated. The drought susceptibility of 25 genotypes was evaluated by comparing yields and yield components in irrigated and non irrigated conditions in the field. A drought susceptibility index (DSI) was calculated based on yields from irrigated and dry treatments and compared with the results obtained using the two physiological criteria. Proline accumulation and chlorophyll fluorescence inhibition were found to be significantly and negatively correlated with DSI of grain yield, biological yield, and thousand kernel weight, and tiller index. The use of both criteria for breeding durum wheat in Mediterranean dryland is discussed.     

Implantation of exogenous enzymatic activity in isolated alveolar macrophages

Alveolar macrophages acquired the capacity to oxidize uric acid after exposure to uricase. Presumably this resulted from intracellular incorporation of the enzyme by endocytosis. This approach may provide a general method for (i) testing regulatory biochemical mechanisms, (ii) therapeutic replacement of deficient regulatory macromolecules, and (iii) studying environmental factors that produce genetic alterations.     

Maize leaf elongation: continuous measurements and close dependence on plant water status

A simple method was developed for measuring extensive intact leaves of monocots on a minute-by-minute basis. Growth was markedly reduced by a slight reduction in leaf water potential. When plants mildly deficient in water were irrigated, growth resumed virtually instantly. The transitional rapid growth aftr watering suggests that water deficit increased cell extensibility.