Effect of the strigolactone analogs methyl phenlactonoates on spore germination and root colonization of arbuscular mycorrhizal fungi

Strigolactones (SLs), a novel class of plant hormones, are key regulator of plant architecture and mediator of biotic interactions in the rhizosphere. Root-released SLs initiate the establishment of arbuscular mycorrhizal (AM) symbiosis by inducing spore germination and hyphal branching in AM fungi (AMF). However, these compounds also trigger the germination of root parasitic weeds, paving the way for deleterious infestation. Availability of SLs is required for investigating of their functions and also for application in agriculture. However, natural SLs are difficult to synthesize due to their complex structure and cannot be isolated at large scale, as they are released at very low concentrations. Therefore, there is a need for synthetic SL analogs. Recently, we reported on the development of simple SL analogs, methyl phenlactonoates (MPs), which show high SL activity in plants. Here, we investigate the effect of MP1, MP3 and the widely used SL-analog GR24 on AMF spore germination and host root colonization. Our results show that MP1 and MP3 inhibit AMF spore germination, but promote the intra-radical root colonization, both more efficiently than GR24. These results indicate that field application of MP1 and MP3 does not have negative impact on mycorrhizal fungi. In conclusion, our data together with the previously reported simple synthesis, high activity in regulating plant architecture and inducing Striga seed germination, demonstrate the utility of MP1 and MP3 as for field application in combating root parasitic weeds by inducing germination in host's absence

The apocarotenoid metabolite zaxinone regulates growth and strigolactone biosynthesis in rice

Strigolactone and abscisic acid are carotenoid-derived plant hormones. Here the authors describe the identification of zaxinone, a further apocarotenoid metabolite, which down-regulates strigolactone content and is required for normal growth and development in rice

Do NERICA rice cultivars express resistance to Striga hermonthica (Del.) Benth. and Striga asiatica (L.) Kuntze under field conditions?

The parasitic weeds Striga asiatica and Striga hermonthica cause high yield losses in rain-fed upland rice in Africa. Two resistance classes (pre- and post-attachment) and several resistant genotypes have been identified among NERICA (New Rice for Africa) cultivars under laboratory conditions (in vitro) previously. However, little is known about expression of this resistance under field conditions. Here we investigated (1) whether resistance exhibited under controlled conditions would express under representative Striga-infested field conditions, and (2) whether NERICA cultivars would achieve relatively good grain yields under Striga-infested conditions. Twenty-five rice cultivars, including all 18 upland NERICA cultivars, were screened in S. asiatica-infested (in Tanzania) and S. hermonthica-infested (in Kenya) fields during two seasons. Additionally, a selection of cultivars was tested in vitro, in mini-rhizotron systems. For the first time, resistance observed under controlled conditions was confirmed in the field for NERICA-2, -5, -10 and -17 (against S. asiatica) and NERICA-1 to -5, -10, -12, -13 and -17 (against S. hermonthica). Despite high Striga-infestation levels, yields of around 1.8 t ha−1 were obtained with NERICA-1, -9 and -10 (in the S. asiatica-infested field) and around 1.4 t ha−1 with NERICA-3, -4, -8, -12 and -13 (in the S. hermonthica-infested field). In addition, potential levels of tolerance were identified in vitro, in NERICA-1, -17 and -9 (S. asiatica) and in NERICA-1, -17 and -10 (S. hermonthica). These findings are highly relevant to rice agronomists and breeders and molecular geneticists working on Striga resistance. In addition, cultivars combining broad-spectrum resistance with good grain yields in Striga-infested fields can be recommended to rice farmers in Striga-prone areas

Methylation at the C-3′ in D-Ring of Strigolactone Analogs Reduces Biological Activity in Root Parasitic Plants and Rice

Strigolactones (SLs) regulate plant development and induce seed germination in obligate root parasitic weeds, e.g. Striga spp. Because organic synthesis of natural SLs is laborious, there is a large need for easy-to-synthesize and efficient analogs. Here, we investigated the effect of a structural modification of the D-ring, a conserved structural element in SLs. We synthesized and investigated the activity of two analogs, MP13 and MP26, which differ from previously published AR8 and AR36 only in the absence of methylation at C-3′. The de-methylated MP13 and MP26 were much more efficient in regulating plant development and inducing Striga seed germination, compared with AR8. Hydrolysis assays performed with purified Striga SL receptor and docking of AR8 and MP13 to the corresponding active site confirmed and explained the higher activity. Field trials performed in a naturally Striga-infested African farmer’s field unraveled MP13 as a promising candidate for combating Striga by inducing germination in host’s absence. Our findings demonstrate that methylation of the C-3′ in D-ring in SL analogs has a negative impact on their activity and identify MP13 and, particularly, MP26 as potent SL analogs with simple structures, which can be employed to control Striga, a major threat to global food security

L'application du droit international humanitaire et des droits fondamentaux dans les conflits armés auxquels prennent part des entités non étatiques

When the instruments of international humanitarian law had to be modernized, the non-international armed conflict was an epiphenomenon and its advent has always been considered a disruptive element of a deeply internationalized international scene. Nevertheless, the growing importance of this type of conflict has highlighted the ever-increasing role of a new type of actors, namely non-State armed groups. From now on, they are the major actors of conflicts largely majority. For this reason, we believe that it is time to change the approach and review the solutions proposed in the applicable international instruments. For all these reasons and to adapt the law to the realities of current conflicts, an approach stripped of any ideological and pejorative burden must take precedence over the current one. Similarly, it is fundamentally necessary to make these groups bear the consequences of their actions by committing their international responsibility.Lorsqu’il a fallu moderniser les instruments du droit international humanitaire le conflit armé non international n’était qu’un épiphénomène et son avènement a toujours été considéré comme un élément perturbateur d’une scène internationale profondément étatisé. Néanmoins l’importance croissante de ce type de conflit a permis de mettre en exergue le rôle sans cesse croissant d’un nouveau type d’acteurs à savoir les groupes armés non étatiques. Désormais, ils sont les acteurs majeurs de conflits largement majoritaires. Pour cette raison, nous pensons qu’il est temps de changer d’approche et de revoir les solutions proposées dans les instruments internationaux applicables. Pour toutes ces raisons et pour adapter le droit aux réalités des conflits actuels, une approche dépouillée de toute charge idéologique et péjorative doit primer par rapport à celle actuelle. De même, il est fondamentalement nécessaire de faire assumer à ces groupes les conséquences de leurs agissements en engageant leur responsabilité internationale

The application of international humanitarian law and fundamental rights in armed conflict involving non-State entities

Lorsqu’il a fallu moderniser les instruments du droit international humanitaire le conflit armé non international n’était qu’un épiphénomène et son avènement a toujours été considéré comme un élément perturbateur d’une scène internationale profondément étatisé. Néanmoins l’importance croissante de ce type de conflit a permis de mettre en exergue le rôle sans cesse croissant d’un nouveau type d’acteurs à savoir les groupes armés non étatiques. Désormais, ils sont les acteurs majeurs de conflits largement majoritaires. Pour cette raison, nous pensons qu’il est temps de changer d’approche et de revoir les solutions proposées dans les instruments internationaux applicables. Pour toutes ces raisons et pour adapter le droit aux réalités des conflits actuels, une approche dépouillée de toute charge idéologique et péjorative doit primer par rapport à celle actuelle. De même, il est fondamentalement nécessaire de faire assumer à ces groupes les conséquences de leurs agissements en engageant leur responsabilité internationale.When the instruments of international humanitarian law had to be modernized, the non-international armed conflict was an epiphenomenon and its advent has always been considered a disruptive element of a deeply internationalized international scene. Nevertheless, the growing importance of this type of conflict has highlighted the ever-increasing role of a new type of actors, namely non-State armed groups. From now on, they are the major actors of conflicts largely majority. For this reason, we believe that it is time to change the approach and review the solutions proposed in the applicable international instruments. For all these reasons and to adapt the law to the realities of current conflicts, an approach stripped of any ideological and pejorative burden must take precedence over the current one. Similarly, it is fundamentally necessary to make these groups bear the consequences of their actions by committing their international responsibility

Specification-Based Intrusion Detection Using Sequence Alignment and Data Clustering

International audienceIn this paper, we present our work on specication-based intrusion detection. Our goal is to build a web application rewall which is able to learn the normal behaviour of an application (and/or the user) from the trac between a client and a server. The model learnt is used to validate future trac. We will discuss later in this paper, the interactions between the learning phase and the exploitation phase of the generated model expressed as a set of regular expressions. These regular expressions are generated after a process of sequence alignment combined to BRELA (Basic Regular Expression Learning Algorithm) or directly by the later. We also present our multiple sequence alignment algorithm called AMAA (Another multiple Alignment Algorithm) and the usage of data clustering to improve the generated regular expressions

The pachycondyla apicalis ants search strategy for data clustering problems

International audienceThis paper presents a work inspired by the Pachycondyla apicalis ants behavior for the clustering problem. These ants have a simple but efficient prey search strategy: when they capture their prey, they return straight to their nest, drop off the prey and systematically return back to their original position. This behavior has already been applied to optimization, as the API meta-heuristic. API is a shortage of api-calis. Here, we combine API with the ability of ants to sort and cluster. We provide a comparison against Ant clustering Algorithm and K-Means using Machine Learning repository datasets. API introduces new concepts to ant-based models and gives us promising results