DISEASE COMPLEX IN TOMATO CV. 035 INVOLVING MELOIDOGYNE INCOGNITA AND FUSARIUM OXYSPORUM F. SP. LYCOPERSICI

Experiments in this investigation indicated that the tomato cv. 035 is moderately resistant to Meloidogyne incognita (Mi) and Fusarium oxysporum f. sp. lycopersici (Fol) since it supports a low population of Mi nematode and retarded fusarial damage in single infections while the plant vigor was unaffected adequately. This resistance was decreased as increased of inoculum levels (from 100 to 2000 IJ2) of Mi and (from 102 to 1010 propagules) of Fol indicating that this resistance is mainly density-dependent. However, co-infection by both pathogens a lesser margin of simulative effect on root galling and wilt severity was occurred. Therefore, wounding by invading IJ5 of Mi proved to be unimportant for establishment of Fol wilt fungus. The results indicated also that, the sequence of infection by nematodes and fungus can predispose the host plant to attack by the other. As with Mi pre infection, nematode causes changes in host that predispose it to fungal attack leading to severe wilt expression. Likewise, pre-infection with for allowed not only more nematode penetration but also more nematode developed than in fungus. Accordingly, the present results led to the fact that, the interactions between Mi nematode and Fol wilt fungus are physiological rather than physical

Actin-Depolymerizing Factor2-Mediated Actin Dynamics Are Essential for Root-Knot Nematode Infection of Arabidopsis

Reorganization of the actin and microtubule networks is known to occur in targeted vascular parenchymal root cells upon infection with the nematode Meloidogyne incognita. Here, we show that actin-depolymerizing factor (ADF) is upregulated in the giant feeding cells of Arabidopsis thaliana that develop upon nematode infection and that knockdown of a specific ADF isotype inhibits nematode proliferation. Analysis of the levels of transcript and the localization of seven ADF genes shows that five are upregulated in galls that result from the infection and that ADF2 expression is particularly increased between 14 and 21 d after nematode inoculation. Further analysis of ADF2 function in inducible RNA interference lines designed to knock down ADF2 expression reveals that this protein is required for normal cell growth and plant development. The net effect of decreased levels of ADF2 is F-actin stabilization in cells, resulting from decreased F-actin turnover. In nematode-infected plants with reduced levels of ADF2, the galls containing the giant feeding cells and growing nematodes do not develop due to the arrest in growth of the giant multinucleate feeding cells, which in turn is due to an aberrant actin network

Conformational restrictions of peptides via backbone modification: Solution and crystal-state analysis of Boc-L-Pro-DZPhe-Gly-NH2

An N-alpha-protected model tripeptide amide containing, in the central position, an alpha,beta-dehydrophenylalanine (Z-configurational isomer), Boc-L-Pro-DELTA-Z-Phe-Gly-NH2 (Boc, tert-butyloxycarbonyl), has been synthesized by solution methods and fully characterized. IR absorption and H-1 NMR studies provided evidence for the occurrence of a significant population of a conformer containing two consecutive, intramolecularly H-bonded (type II-III') beta-bends in solution. However, an X-ray diffraction analysis clearly indicates that only the type-II beta-bend structure survives in the crystal state

Feeding cells induced by phytoparasitic nematodes require y-Tubulin ring complex for microtubule reorganization

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Grapevine Resistance to the Nematode Xiphinema index

Breeding for varieties carrying natural resistance (R) against plant-parasitic nematodes is a promising alternative to nematicide ban. In perennial crops, the long plant-nematode interaction increases the risk for R breaking and R durability is a real challenge. In grapevine, the nematode has a high economic impact by transmitting (GFLV) and, to delay GFLV transmission, rootstocks resistant to this vector are being selected, using in particular as an R source. To optimize this strategy, the durability has been studied under controlled conditions in F1 and BC1 muscadine-derived resistant accessions previously obtained from either hardwood-cutting or in vitro propagation. After inoculation with a mix, in equal proportions, of four lines representative of the diversity, multiplication on plants has been monitored 3 to 6 years. The nematode reproduction factor remained lower than 1 in resistant plants obtained from hardwood cuttings while it increased at values far beyond 1 in resistant plants of in vitro origin. Data for nematode numbers per gram of roots mostly paralleled those obtained for the reproduction factor. The effect of the propagation type on resistance over years was also evaluated for the ratio female/juvenile and the frequency of males. Altogether our results illustrate that the muscadine-derived resistance based on hardwood cuttings is durable. By contrast, in resistant and reference accessions obtained from in vitro, our data suggest that the increased nematode multiplication might be mainly due to the modification of root architecture consecutive to this propagation method