Seeing the forest for the trees: Use of phages to treat bacterial tree diseases     

Emily R. Grace  Mojgan Rabiey  Ville-Petri Friman  Robert W. Jackson 《Plant pathology》2021,70(9):1987-2004

Trees and woody plants can be attacked by many pests and pathogens either individually or as polymicrobial infections. In particular, infections caused by tree-specific bacterial pathogens have become more common during the last decade, causing serious concern for important tree and woody plant species in horticulture, urban environments, and forests. For example, Xylella and Pseudomonas bacteria are causing significant economic and ecological devastation throughout Europe in olive, cherry, and other stone fruits, mainly because of lack of efficient control methods and the emergence of bacterial resistance to traditional antimicrobial compounds such as copper and antibiotics. Hence, there is an urgent need for innovative approaches to tackle bacterial plant diseases. One way to achieve this could be through the application of biological control, which offers a more environmentally friendly and targeted approach for pathogen management. This review will explore recent advances in use of pathogen-specific viruses, bacteriophages (or phages), for the biocontrol of bacterial tree diseases. Phages are an important component of plant microbiomes and are increasingly studied in plant pathogen control due to their highly specific host ranges and ability to selectively kill only the target pathogenic bacteria. However, their use still poses several challenges and limitations, especially in terms of managing the bacterial diseases of long-lived trees. A particular insight will be given into phage research focusing on controlling Pseudomonas syringae pathovars, Erwinia amylovora, Xanthomonas species, Ralstonia solanacearum, and Agrobacterium tumefaciens. Recent milestones, current challenges, and future avenues for phage therapy in the management of tree diseases are discussed.  相似文献   

Simulation of corn yields in the Upper Great Lakes Region of the US using a modeling framework     

Gene R. Safir  Stuart H. Gage  Manuel Colunga-Garcia  Peter Grace  Shapoor Rowshan 《Computers and Electronics in Agriculture》2008,60(2):301-305

We examined the utility of a site-based simulation model for corn (MAIZE) applied to the Upper Great Lakes Region (UGLR) of the United States for 1992–1996. To evaluate model outputs, we used a modeling applications system integrative framework (MASIF) to simulate corn yields in the UGLR. We divided the region into two ecological zones (upper UGLR-1 and lower UGLR-2) and compared MAIZE and USDA National Agriculture Statistics Service (NASS) yield estimates in each zone. There was greater agreement between MAIZE and NASS yields at lower yield values. As NASS yields increased, MAIZE yields also increased, but to a greater extent than did NASS yields. We conducted a mean spatial analysis of maize yield from 1992 to 1996. We also conducted a spatial analysis of 1994, 1995 and 1996. There are both spatial and temporal differences when yields are mapped.  相似文献   

Land-use changes alter CO2 flux patterns of a tall-grass Andropogon field and a savanna-woodland continuum in the Orinoco lowlands     

San José J  Montes R  Grace J  Nikonova N 《Tree physiology》2008,28(3):437-450

Land use changes in the savannas of the Orinoco lowlands have resulted in a mosaic of vegetation. To elucidate how these changes have affected carbon exchanges with the atmosphere, we measured CO2 fluxes by eddy covariance and soil CO2 efflux systems along a disturbance gradient beginning with a cultivated tall-grass Andropogon field (S1) and extending over three savanna sites with increasing woody cover growing above native herbaceous vegetation. The savanna sites included a herbaceous savanna (S2), a tree savanna (S3) and a woodland savanna (S4). During the wet season, maximum diurnal net ecosystem exchange (NEE) over the S1-S4 sites was 6.6-9.3, 6.6-7.9, 10.6-11.3 and 9.3-10.6 micromol m(-2) s(-1), respectively. The rate of CO2 uptake over S1 was lower than that for C4 grasses elsewhere because of pasture degradation. Soil respiration and temperature were exponentially related when soil water content (theta) was above 0.083 m(3) m(-3); however, soil respiration declined markedly as theta decreased from 0.083-0.090 to 0.033-0.056 m(3) m(-3). There were bursts of CO2 emission when dry soils were rewetted by rainfall. During the wet season, all sites constituted carbon sinks with maximum net daily ecosystem production (NEP) of 2.1, 1.7, 2.1 and 2.1 g C m(-2) day(-1), respectively. During the dry season, the savanna sites (S2-S4) became carbon sources with maximum emission fluxes of -0.5, -1.4 and -1.6 g C m(-2) day(-1), respectively, whereas the tall-grass field (S1) remained a carbon sink with a maximum NEP of 0.3 g C m(-2) day(-1) at the end of the season. For all measurement periods, annual NEP of sites S1-S4 was 366, 6, 116 and 139 g C m(-2), respectively. Comparisons of carbon source/sink dynamics across a wide range of savannas indicate that savanna carbon budgets can change in sign and magnitude. On an annual basis, gross primary production over the S1-S4 stands was 797, 803, 136 and 1230 g C m(-2), respectively. Net primary productivity (NPP) of the S1-S4 stands, calculated from eddy covariance measurements as the daily sum of NEE and day and night heterotrophic respiration was 498, 169, 181 and 402 g C m-2 year-1, respectively. These values were slightly higher than NPP based on harvest measurements (432, 162, 176 and 386 g C m(-2) year(-1), respectively), presumably because fine roots were incompletely harvested. Soil water content limited carbon uptake at all sites, and water-use efficiency (WUE) was related to rainfall dynamics. During the dry season, all sites except the cultivated tall-grass Andropogon field (S1) had a negative WUE. Although our results are specific to the Orinoco vegetational mosaic, the effects of land-use practices on the controls and physiological functions of the studied ecosystems may be generalized to other savannas.  相似文献   

Mycorrhizal fungi of radiata pine in different forests of the north and south islands in New Zealand     

Myra Chu-Chou  Lynette J. Grace 《Soil biology & biochemistry》1988,20(6):883-886

Mycorrhizal fungi of radiata pine (Pinus radiata D. Don) planted in forests established on different soil types (sand, pumice-scoria and clay) located in the North and South Islands of New Zealand were studied. There were no major differences in the mycorrhizal fungal species between the forests in the North and South Islands and the most common mycorrhizal fungi were Rhizopogon rubescens Tul. and Suillus luteus (L. ex. Fr.) S.F. Gray.

The different soil types did affect the number of myocrrhizal fungal species and the abundance of sporocarps of this fungi. The largest number of fungal species were found in forests established on pumice-scoria.  相似文献   

Bacteriological quality and safety of ready-to-consume milk and naturally fermented milk in Borana pastoral area,southern Ethiopia     

Amenu  Kebede  Grace  Delia  Nemo  Shemsu  Wieland  Barbara 《Tropical animal health and production》2019,51(7):2079-2084

Tropical Animal Health and Production - Milk and milk products play an important role in the diet of pastoralists in Ethiopia. However, only few studies have been conducted on the microbial...  相似文献   

Tanglehead in Southern Texas: A Native Grass with an Invasive Behavior     

David B. Wester  Fred C. Bryant  Aaron D. Tjelmeland  Joshua L. Grace  Scott L. Mitchell  John T. Edwards  Fidel Hernández  Robert K. Lyons  Megan K. Clayton  Sandra Rideout-Hanzak  Richard V. Machen  J. Alfonso Ortega-S. 《Herpetological Monographs》2018,40(2):37-44

  相似文献   

Genetic Variations in Populations from Farms and Natural Habitats of Asian Green Mussel,Perna viridis,in Singapore Inferred from Nine Microsatellite Markers     

Grace Lin  Loong Chueng Lo  Gen Hua Yue 《Journal of the World Aquaculture Society》2012,43(2):270-277

The Asian green mussel, Perna viridis, has been widely cultured in Southeast Asia as delicious seafood depending on natural spat. We analyzed the genetic diversity and population structure of three populations (two from Singapore and one from Malaysia) from natural habitats and two from Singapore farms, by genotyping a total of 262 adult individuals using nine polymorphic microsatellites. In all five populations, high allelic (number of alleles A = 11.0–14.4,allelic richness Ar = 10.4–13.9) and gene diversity (expected heterozygosity He = 0.73–0.77) were observed, whereas deficiency of heterozygosity (inbreeding index f = 0.08–0.12) was detected in all populations. Genetic differentiation among populations was low (pairwise fixation index ranged from 0.003 to 0.088), but statistically significant. The usefulness of the information about genetic variations for genetic resource management of the populations in wild habitats and farms to keep genetic variation and setting up a breeding program of Asian green mussel was discussed.  相似文献   

Rickets in alpacas (Lama paces) in New Zealand     

F.I. Hill  K.G. Thompson  N.D. Grace 《New Zealand veterinary journal》2013,61(6):229-232

Rickets was diagnosed in two weaner alpacas from a flock showing ill thrift and lameness during the winter of 1992. Both animals had abnormally shaped ribs with occasional healing fractures, irregular thickening of growth plates and metaphyseal haemorrhages. The mean serum phosphorus concentrations of the alpacas fell during June and July, even though lambs grazing the same pasture had normal serum phosphorus concentrations and the phosphorus concentration of the pasture was considered adequate. Vitamin D deficiency may also have contributed to the osteodystrophy. The alpacas had a thick fleece during the winter, and diurnal Vitamin D₃, synthesis resulting from solar irradiation is likely to have been minimal, especially considering the reduced sunshine hours recorded during the 1992 winter. Surviving alpacas recovered after treatment with monosodium phosphate and an oral Vitamin D supplement. It is possible alpacas are more susceptible to deficiencies of phosphorus and Vitamin D than other grazing animals in New Zealand.  相似文献   

Climate influences the leaf area/sapwood area ratio in Scots pine     

Mencuccini M  Grace J 《Tree physiology》1995,15(1):1-10

We tested the hypothesis that the leaf area/sapwood area ratio in Scots pine (Pinus sylvestris L.) is influenced by site differences in water vapor pressure deficit of the air (D). Two stands of the same provenance were selected, one in western Scotland and one in eastern England, so that effects resulting from age, genetic variability, density and fertility were minimized. Compared with the Scots pine trees at the cooler and wetter site in Scotland, the trees at the warmer and drier site in England produced less leaf area per unit of conducting sapwood area both at a stem height of 1.3 m and at the base of the live crown, whereas stem permeability was similar at both sites. Also, trees at the drier site had less leaf area per unit branch cross-sectional area at the branch base than trees at the wetter site. For each site, the average values for leaf area, sapwood area and permeability were used, together with values of transpiration rates at different D, to calculate average stem water potential gradients. Changes in the leaf area/sapwood area ratio acted to maintain a similar water potential gradient in the stems of trees at both sites despite climatic differences between the sites.  相似文献   

Magnetic resonance imaging used for the evaluation of water presence in wood plastic composite boards exposed to exterior conditions     

Marek Gnatowski  Rebecca Ibach  Mathew Leung  Grace Sun 《Wood material science & engineering》2015,10(1):94-111

Abstract

Two wood plastic composite (WPC) boards, one experimental and one commercial, were exposed to exterior conditions and evaluated non-destructively using a clinical magnetic resonance imaging (MRI) unit for moisture content (MC) and distribution. The experimental board was exposed in Vancouver, British Columbia, for more than 8 years, and the commercial board was exposed near Hilo, Hawaii, for 2 years. Both boards were characterized in terms of wood content, density, water uptake properties and voids content. The experimental board was additionally destructively analysed for water absorption of the WPC and MC calculated based on the wood content for verification of MRI results. MRI detected the presence of free water and its distribution in both of the WPC boards. Fibre saturation in the experimental board was found to be about 22–24%, in comparison to 25–30% present in most wood species. There was good correlation between the detection of free water by MRI and by destructive testing. Magnetic resonance images showed various major points of water entry in the WPC boards such as the support area, the cut ends, the dripping edge and the sides of the boards. For the experimental board, significant water entry also occurred at the upper exposed surface.  相似文献