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1.
X. Wang    Y. Jacob    S. Mastrantuono    J. Bazzano    R. Voisin  D. Esmenjaud 《Plant Breeding》2004,123(1):79-83
The spectrum and inheritance of resistance to the root‐knot nematode Meloidogyne hapla was studied in the diploid species Rosa multiflora and R. indica. The host suitability of seven rose rootstocks, namely five R. multiflora (K2, K1, Floradale, CE63 and CE65) and two R. indica (CE35 and Maroc) clonal accessions, was evaluated using four geographic isolates of M. hapla. Plants grown under greenhouse conditions were tested at high and durable inoculum pressure of nematodes and rated for nematode infestation five months after inoculation on a 0–5 gall index. Different host suitabilities to M. hapla were demonstrated depending on the nematode isolates: in R. multiflora, the clone K2 had a resistant (R) response to all isolates; the clone K1 ranged from intermediate (I) (isolate ‘Canada’) to resistant (other isolates), Floradale was shown to be intermediate, whereas CE63 and CE65 were moderate to good hosts (H). In R. indica, both rootstocks were good to excellent hosts for the isolate Canada but resistant to all three other isolates, thus expressing an isolate‐specific resistance. A study on the genetics of resistance in R. multiflora to the M. hapla isolate Canada was then conducted using an incomplete diallel cross involving all previous clones except Floradale. A total of 120 hybrid individuals belonging to several progenies representing the cross combinations R × I, R × H, I × H and H × H were evaluated. Individuals of each progeny generally ranged into a monomodal distribution that suggests polygenic inheritance of resistance. In the family Rosaceae, the differences in the resistance genetics to the meiotic species M. hapla and to the mitotic species, M. arenaria, M. incognita and M. javanica are discussed in relation to the reproductive status of the nematodes.  相似文献   
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Background

In order to maintain high yields while saving water and preserving non-renewable resources and thus limiting the use of chemical fertilizer, it is crucial to select plants with more efficient root systems. This could be achieved through an optimization of both root architecture and root uptake ability and/or through the improvement of positive plant interactions with microorganisms in the rhizosphere. The development of devices suitable for high-throughput phenotyping of root structures remains a major bottleneck.

Results

Rhizotrons suitable for plant growth in controlled conditions and non-invasive image acquisition of plant shoot and root systems (RhizoTubes) are described. These RhizoTubes allow growing one to six plants simultaneously, having a maximum height of 1.1 m, up to 8 weeks, depending on plant species. Both shoot and root compartment can be imaged automatically and non-destructively throughout the experiment thanks to an imaging cabin (RhizoCab). RhizoCab contains robots and imaging equipment for obtaining high-resolution pictures of plant roots. Using this versatile experimental setup, we illustrate how some morphometric root traits can be determined for various species including model (Medicago truncatula), crops (Pisum sativum, Brassica napus, Vitis vinifera, Triticum aestivum) and weed (Vulpia myuros) species grown under non-limiting conditions or submitted to various abiotic and biotic constraints. The measurement of the root phenotypic traits using this system was compared to that obtained using “classic” growth conditions in pots.

Conclusions

This integrated system, to include 1200 Rhizotubes, will allow high-throughput phenotyping of plant shoots and roots under various abiotic and biotic environmental conditions. Our system allows an easy visualization or extraction of roots and measurement of root traits for high-throughput or kinetic analyses. The utility of this system for studying root system architecture will greatly facilitate the identification of genetic and environmental determinants of key root traits involved in crop responses to stresses, including interactions with soil microorganisms.
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4.
The effect of RUS, a major quantitative resistance (QR) factor inherited from Populus trichocarpa, was assessed in two Populus deltoides × P. trichocarpa F1 progenies against eight isolates of Melampsora larici‐populina, the causal agent of Eurasian poplar rust. Six isolates were identified on which RUS had no significant effect. The first RUS‐defeating isolate identified suggested a pre‐existing potential to overcome RUS in the pathogen’s populations. The P. deltoides genetic background made no difference either to the ability of a given isolate to overcome RUS or to the relative and absolute aggressiveness of the isolates. This study illustrates how extreme the isolate‐specificity of QR can be. It also yields insights into the relationship between size of uredinia and sporulation rate, discussing the epidemiological significance of spore production per mm2 uredinium.  相似文献   
5.
Penetration, development and emigration of M. arenaria in the roots of three Myrobalan plum (Prunus cerasifera) clones genetically characterized for their resistance to root-knot nematodes (RKN) were studied during the 10 (penetration) and 15 (emigration) days following the date of inoculation (D) of 2500 juveniles (J2s) per plant into the soil. Miniaturized tests were conducted on the two resistant clones P.2175 (Ma1 gene) and P.1079 (Ma2 gene) and the susceptible clone P.2032 (recessive for both genes), obtained from micropropagated plantlets and grown in mini-containers under controlled conditions at 25°C in a growth chamber. For penetration and development studies, nematodes in the roots were recovered by the acid fuchsin-lactophenol staining technique. Equivalent numbers of J2s were recovered in all the clones at D+1 and D+2. Subsequently, the numbers increased rapidly in P.2032 and were significantly different from those in P.1079 and P.2175 that remained at a low level. No swollen larvae were observed in the resistant clones. In P.2032, the first swollen larvae were observed at D+4, the first females were observed at D+12, whereas the first females with attached egg sacs and the first new-generation J2s were obtained between D+21 and D+28. Our data suggest that the resistance phenomenon does not act on the very early nematode penetration but acts later by preventing feeding-site induction and development into the third-stage. For emigration studies, plants in which J2s had been allowed to penetrate for two days (from D to D+2) were washed free of soil, repotted and then, after various periods of growth, soil-free roots were placed under a mistifier to evaluate the numbers of emigrating individuals. Emigration of J2s from the roots occured mainly from D+2 to D+4 in all the genotypes and was very limited from D+4 to D+10. There was no significant differences in the number of emigrated juveniles between the resistant and susceptible clones, indicating that emigration cannot explain the difference in the numbers of nematodes recovered in the roots.  相似文献   
6.
In humans, magnetic resonance (MR) imaging is the method of choice for the diagnosis of stress fractures. In this paper, bilateral stress fracture of the lateral condyle of the third metacarpal bone in a French trotter is described. Results of the radiographic, MR imaging, and histologic examinations are presented, with a focus on the MR signal abnormalities found. Based on this patient, the potential use of MR imaging for the diagnosis of stress fractures in horses is discussed.  相似文献   
7.
ABSTRACT The species X. index, X. diversicaudatum, X. vuittenezi, and X. italiae are established (E) or putative (P) vectors of Grapevine fanleaf virus (GFLV) (E), Arabis mosaic virus (E), Grapevine chrome mosaic virus (P), and GFLV (P) nepoviruses of grapevine, respectively. All four species are very closely related taxonomically and their low field densities make them difficult to identify from morphological and morphometrical diagnostic characters when only single or few individuals are detected. To improve diagnostic accuracy, a simple method was developed. The internal transcribed spacer 1 (ITS1) region spanning the 18S and 5.8S ribosomal genes was sequenced in one population of each species using two conserved primers from these genes. The ITS1 fragments were 1,132 bp (X. vuittenezi), 1,153 bp (X. index), 1,175 bp (X. diversicaudatum), and 1,190 bp (X. italiae), i.e., a difference of over 5% between the extremes. The sequence variability made it possible to design species-specific internal sense primers that amplified, in combination with the same antisense ITS1 primer, a single signature fragment (340 bp for X. index, 414 bp for X. italiae, 591 bp for X. vuittenezi, and 813 bp for X. diversicaudatum). Tests with DNA from a single adult or juvenile nematode confirmed the specificity of the primers from diverse isolates or populations. The primers were successfully used in a multiplex test for the reliable detection of two to four mixed species, each represented by a single individual. This multiplex-based diagnostic tool will be particularly useful for successful nematode management practices in vineyards.  相似文献   
8.
Kovacs  Jennifer L.  Wolf  Candice  Voisin  Dené  Wolf  Seth 《BMC ecology》2017,17(1):1-3
Background

Learning processes can be broadly categorized into associative and non-associative. Associative learning occurs through the pairing of two previously unrelated stimuli, whereas non-associative learning occurs in response to a single stimulus. How these two principal processes compare in the same learning task and how they contribute to the overall behavioural changes brought about by experience is poorly understood. We tackled this issue by scrutinizing associative and non-associative learning of prey, Western flower thrips Frankliniella occidentalis, by the predatory mite, Neoseiulus californicus. We compared the behaviour of thrips-experienced and -naïve predators, which, early in life, were exposed to either thrips with feeding (associative learning), thrips without feeding (non-associative learning), thrips traces on the surface (non-associative learning), spider mites with feeding (thrips-naïve) or spider mite traces on the surface (thrips-naïve).

Results

Thrips experience in early life, no matter whether associative or not, resulted in higher predation rates on thrips by adult females. In the no-choice experiment, associative thrips experience increased the predation rate on the first day, but shortened the longevity of food-stressed predators, a cost of learning. In the choice experiment, thrips experience, no matter whether associative or not, increased egg production, an adaptive benefit of learning.

Conclusions

Our study shows that both non-associative and associative learning forms operate in foraging predatory mites, N. californicus. The non-rewarded thrips prey experience produced a slightly weaker, but less costly, learning effect than the rewarded experience. We argue that in foraging predatory mites non-associative learning is an inevitable component of associative learning, rather than a separate process.

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9.
Nine Myrobalan plum clones ( Prunus cerasifera ) obtained from in vitro propagation were tested for host suitability to four root-knot nematode (RKN) isolates ( Meloidogyne incognita (2), M. javanica (1), and M. hispanica (1)) and one root-lesion nematode (RLN), Pratylenchus vulnus , isolate. The clones are characterized according to the Ma major resistance genes that control resistance to M. arenaria , M. incognita and M. javanica and are categorized into five resistant (R) and four host (H) clones to these RKN species. As expected, the clones ranged, regardless of the RKN species or isolate, into the same distinct R (P.2175, P.1079, P.2980, H.17 and H.21) and H (P.2794, H.18, H.23 and P.16.5) groups for RKN resistance. The P. vulnus tests showed that all the clones had higher final populations than initial populations ( P f :  P i > 1) and that P f :  P i ratios were equivalent in each RKN resistance group (R or H). Consequently, resistant alleles of RKN Ma genes in Myrobalan plum have no major effect on RLN multiplication. Our data must be taken into account for breeding strategies aimed at incorporating multiple resistance to both RKN and RLN in Prunus spp.  相似文献   
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