Suppression of Jasmonic Acid-Dependent Defense in Cotton Plant by the Mealybug Phenacoccus solenopsis

The solenopsis mealybug, Phenacoccus solenopsis, has been recently recognized as an aggressively invasive pest in China, and is now becoming a serious threat to the cotton industry in the country. Thus, it is necessary to investigate the molecular mechanisms employed by cotton for defending against P. solenopsis before the pest populations reach epidemic levels. Here, we examined the effects of exogenous jasmonic acid (JA), salicylic acid (SA), and herbivory treatments on feeding behavior and on development of female P. solenopsis. Further, we compared the volatile emissions of cotton plants upon JA, SA, and herbivory treatments, as well as the time-related changes in gossypol production and defense-related genes. Female adult P. solenopsis were repelled by leaves from JA-treated plant, but were not repelled by leaves from SA-treated plants. In contrast, females were attracted by leaves from plants pre-infested by P. solenopsis. The diverse feeding responses by P. solenopsis were due to the difference in volatile emission of plants from different treatments. Furthermore, we show that JA-treated plants slowed P. solenopsis development, but plants pre-infested by P. solenopsis accelerated its development. We also show that P. solenopsis feeding inhibited the JA-regulated gossypol production, and prevented the induction of JA-related genes. We conclude that P. solenopsis is able to prevent the activation of JA-dependent defenses associated with basal resistance to mealybugs

Single-mode cavities at frequencies of 172 and 178 MHz

In the report presented here the projects of two accelerating cavities with strong damping of higher modes (HOM) with special vacuum loads are presented. The designs of the cavities and loads are described. The design parameters of cavities, their spectra of higher modes and calculation results of the beam phase motion stability are given for the VEPP-2000 and NANOHANA Projects

Architecture d'un systeme adapte au traitement du signal

Devant faire face à un problème temps réel nécessitant : - une puissance de calcul comparable à celle des plus gros ordinateurs actuels, - une grande mobilité de l'installation, nous avons été amenés à étudier une architecture matérielle capable de subvenir à nos besoins. Cette architecture fait appel aux techniques modernes que sont l'informatique distribuée et l'array processing. Les objectifs, la conception et la réalisation d'un système souple et performant nous ont fait rejeter les logiciels généraux et par conséquent mal adaptés à ce genre de problème. Nous avons donc développé entièrement les logiciels de base nécessaires au bon fonctionnement de l'ensemble. Il est intéressant de suivre la démarche employée, les solutions originales adoptées, la méthodologie mise en oeuvre pour résoudre nos problèmes. Il importe de cerner le progrès, les perspectives qu'une telle configuration apporte dans les domaines exigeants en temps réel que sont le traitement du signal, le traitement d'images et la reconnaissance de formes

Etude de riz transgéniques résistants à la maladie du tungro, avec obtention de lignées quasi-immunes contre le "rice tungro spherical virus$

International audienc

A novel patatin-like protein from cotton plant, GhPat1, is co-expressed with GhLox1 during Xanthomonas campestris-mediated hypersensitive cell death

In cotton plant, Xanthomonas-induced hypersensitive response (HR) is accompanied by a lipid peroxidation process involving a 9-lipoxygenase (LOX), GhLox1. Initiation of this oxidative metabolism implies the release of the LOX substrates, or polyunsaturated fatty acids. Since patatin-like proteins (PLPs) are likely candidates for mediating the latter step, we searched for genes encoding such enzymes, identified and cloned one of them that we named GhPat1. Biochemical and molecular studies showed that GhPat1 expression was up-regulated during the incompatible interaction, prior to the onset of the corresponding galactolipase activity and cell death symptoms in tissues. Protein sequence analysis and modelling also revealed that GhPat1 catalytic amino acids and fold were conserved across plant PLPs. Based on these results and our previous work (Jalloul et al. in Plant J 32: 1-12, 2002), a role for GhPat1, in synergy with GhLox1, during HR-specific lipid peroxidation is discussed

The 9-lipoxygenase GhLOX1 gene is associated with the hypersensitive reaction of cotton Gossypium hirsutum to Xanthomonas campestris pv malvacearum

Hypersensitive reaction (HR) cell death of cotton to the incompatible race 18 from Xanthomonas campestris pathovar malvacearum (Xcm) is associated with 9S-lipoxygenase activity (LOX) responsible for lipid peroxidation. Here, we report the cloning of cotton (Gossypium hirsutum L.) LOX gene (GhLOXI) and the sequencing of its promoter. GhLOXI was found to be highly expressed during Xcm induced HR. Sequence analysis showed that GhLOXI is a putative 9-LOX, and GhLOXI promoter contains SA and JA responsive elements. Investigation on LOX signalisation on cotyledons infiltrated with salicylic acid (SA), or incubated with methyl-jasmonate (MeJA) revealed that both treatments induced LOX activity and GhLOXI gene expression. HR-like symptoms were observed when LOX substrates were then injected in treated (MeJA and SA) cotyledons or when Xcm compatible race 20 was inoculated on MeJA treated cotyledons. Together these results support the fact that GhLOXI encodes a 9 LOX whose activity would be involved in cell death during cotton HR