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1.
Oded Cohen Ozgur Batuman Yoni Moskowits Alexander Rozov Elisha Gootwine Munir Mawassi Moshe Bar-Joseph 《Phytoparasitica》2005,33(2):141-148
Mechanical inoculations with contaminating tools and propagation of infected budwood were considered the main causes for the
omnipresence of multiple viroid species among citrus and other Middle Eastern and Mediterranean fruit trees and grapevines.
However, neither means could explain viroid infections of wild trees — scattered on terrains inaccessible to humans — nor
the finding of similar viroids among graft-incompatible plants. Northern hybridization of RNA extracts made of scrapings from
the surfaces of goat (Capra hircus) horns that were rubbed against etrog (Citrus medica) stems infected with a citrus viroids complex, revealed accumulation of considerable amounts ofCitrus exocortis viroids (CEVd) andHop stunt viroids (HSVd). Experimental transmission of both CEVd and HSVd was obtained by rubbing healthy citrus plants with goat horns that
had been rubbed 24 h earlier on infected etrog stems. These results implicate goats as possible vectors of viroids. Transmissionvia goats could have facilitated the long-range spread of viroids among cultivated and wild plants andvice versa and also among graft-incompatible plants. 相似文献
2.
Cells use transporters of different affinities to regulate nutrient influx. When nutrients are depleted, low-affinity transporters are replaced by high-affinity ones. High-affinity transporters are helpful when concentrations of nutrients are low, but the advantage of reducing their abundance when nutrients are abundant is less clear. When we eliminated such reduced production of the Saccharomyces cerevisiae high-affinity transporters for phosphate and zinc, the elapsed time from the initiation of the starvation program until the lack of nutrients limited growth was shortened, and recovery from starvation was delayed. The latter phenotype was rescued by constitutive activation of the starvation program. Dual-transporter systems appear to prolong preparation for starvation and to facilitate subsequent recovery, which may optimize sensing of nutrient depletion by integrating internal and external information about nutrient availability. 相似文献
3.
As a result of rapid land development in Israel during the past three decades, some 26 species of higher plants, about one percent of the local flora, have become extinct. In addition to listing such species, this paper deals with the ecological implications of this finding. Recommendations for the prevention of further damage to the local flora, and rare plants in particular, are given. 相似文献
4.
Y. Chen Y. Inbar S. Zilkah A. Koren M. Dinar M. Gokkes M. Raviv R. Reuveni Shlomot Medina Y. Shamir Orna Etzion Orna Duvdevani Y. Shor R. Schayer Ester Hadar Ruhama Berliner A. Gamliel J. Katan G. Kritzman Leah Tsror A. Nachmias V. Weitsman D. Mor Y. Inbar M. J. Boehm H. A. J. Hoitink Y. Hadar Y. Elad H. Yunis H. Volpin E. Pressman A. Gamliel J. Katan M. Sachs 《Phytoparasitica》1991,19(2):161-170
5.
An artificial capillary barrier to improve root zone conditions for horticultural crops: physical effects on water content 总被引:1,自引:1,他引:0
Eviatar Ityel Naftali Lazarovitch Moshe Silberbush Alon Ben-Gal 《Irrigation Science》2011,29(2):171-180
Capillary barriers (CBs) occur at the interface of two soil layers having distinct differences in textural and hydraulic characteristics.
The objective of this study was to introduce an artificial CB, created by a layer of gravel below the root zone substrate,
in order to optimize conditions for the cultivation of horticultural crops. Potential root zone formats were analyzed with
and without the gravel CBs for variables including the following: depth of CB; barrier separating the root zone from the surrounding
soil; and root zone soil texture. Field and simulated results revealed that artificial CBs increased root zone water content
and changed water flow dynamics. Volumetric soil water content was increased by 20–70%, depending on the soil texture and
depth of the barrier. Sandy soil texture and shallower placement resulted in relatively higher water content. For sandy soil
without plants, a shallow (0.2 m depth) CB increased water content of the overlaying soil by 50% compared to the control.
The introduction of a gravel CB below the root zone of pepper plants (Capsicum Annum L.) lead to 34% higher matric head, 50% lower diurnal fluctuations in matric head and 40% increase in pepper fruit yield.
Increasing water content by way of artificial CBs appeared to improve the water use efficiency of pepper plants. Such an improvement
could lead to reduced water and fertilizer application rates and subsequent reduction in contamination below the root zone.
This is especially relevant for substrates of low water-holding capacity typically used in horticulture crop production. 相似文献
6.
Lev-Yadun S Ne'eman G Abbo S Flaishman MA 《Science (New York, N.Y.)》2006,314(5806):1683; author reply 1683
Kislev et al. (Reports, 2 June 2006, p. 1372) described Neolithic parthenocarpic fig fruits and proposed that they derive from trees propagated only by cuttings and thus represent the first domesticated plant of the Neolithic Revolution. Because parthenocarpic fig trees naturally produce both seeded and seedless fruits and are capable of spontaneous reproduction, we argue that the finds do not necessarily indicate cultivation, nor horticulture predating grain crops. 相似文献
7.
Shpyrko OG Streitel R Balagurusamy VS Grigoriev AY Deutsch M Ocko BM Meron M Lin B Pershan PS 《Science (New York, N.Y.)》2006,313(5783):77-80
X-ray measurements reveal a crystalline monolayer at the surface of the eutectic liquid Au82Si18, at temperatures above the alloy's melting point. Surface-induced atomic layering, the hallmark of liquid metals, is also found below the crystalline monolayer. The layering depth, however, is threefold greater than that of all liquid metals studied to date. The crystallinity of the surface monolayer is notable, considering that AuSi does not form stable bulk crystalline phases at any concentration and temperature and that no crystalline surface phase has been detected thus far in any pure liquid metal or nondilute alloy. These results are discussed in relation to recently suggested models of amorphous alloys. 相似文献
8.
9.
Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is an explosive compound whose extensive use has resulted in significant contamination of soils and groundwater worldwide. We studied its in situ biodegradation along the unsaturated zone beneath an explosives wastewater lagoon using compound-specific isotope analysis (CSIA) of RDX in the unsaturated zone, together with biodegradation slurry experiments under anaerobic conditions. We found the highest degradation potential of RDX and its nitroso derivatives in the upper part of the soil profile while in the lower parts, RDX-degradation potential was lower and the nitroso derivatives tended to persist. This was also observed in the field, as reflected by the isotopic composition of RDX along the profile. We also found a correlation between biodegradation potential and clay content: biodegradation was further enhanced in layers characterized by high-clay content or in those influenced by the high-clay layers. In addition, in the presence of high organic matter content, further enhancement of biodegradation was observed. We obtained different isotopic enrichment factors (?) for RDX biodegradation in different sections of the unsaturated profile and suggest that different degradation pathways exist simultaneously in situ, in variable proportions. Using the range of enrichment factors, we were able to assess the biodegradation extent of RDX at different sampling points along the profile, which ranged between 30 and 99.4%. The novel application of CSIA together with slurry experiments provides better insight into degradation processes that are otherwise difficult to detect and assess. 相似文献
10.
Kerem Z Bilkis I Flaishman MA Sivan L 《Journal of agricultural and food chemistry》2006,54(4):1243-1247
The roots of Rumex bucephalophorus, collected in Israel, were analyzed for trans-stilbenes. Two stilbene-O-glycosyl derivatives were identified, in addition to 3,5,4'-trihydroxystilbene (1) (resveratrol). The stilbene-O-glycosyl derivatives were 5,4'-dihydroxystilbene-3-O-beta-d-glucopyranoside (2) (piceid) and the new 5,4'-dihydroxystilbene-3-O-alpha-arabinopyranoside (3), which is being named rumexoid. The structure of rumexoid was elucidated by using spectroscopic data. The antioxidant capacities of stilbenoids 1-3 were determined and expressed as trolox equivalent antioxidant capacity (TEAC). TEAC value for trans-resveratrol was highest (2.7) and for rumexoid lowest (1.5). In vitro, trans-resveratrol and rumexoid demonstrated a potent inhibitory effect on alpha-glucosidase activity (IC50 < 0.1 and < 0.5 mM, respectively). The commercial antidiabetic agent acarbose was shown to inhibit only 35% of the enzyme activity at 0.5 mM. The addition of piceid to the reaction mixture did not inhibit alpha-glucosidase in vitro in the range of concentrations used. These findings extend the range of reported beneficial effects of stilbene derivatives, and demonstrate the multifaceted activities that dietary polyphenols may exert in the intestine, where their concentrations are highest in the body. 相似文献