Marker-Assisted Pyramiding of Blast-Resistance Genes in a japonica Elite Rice Cultivar through Forward and Background Selection

Rice blast, caused by Pyricularia oryzae, is one of the main rice diseases worldwide. The pyramiding of blast-resistance (Pi) genes, coupled to Marker-Assisted BackCrossing (MABC), provides broad-spectrum and potentially durable resistance while limiting the donor genome in the background of an elite cultivar. In this work, MABC coupled to foreground and background selections based on KASP marker assays has been applied to introgress four Pi genes (Piz, Pib, Pita, and Pik) in a renowned japonica Italian rice variety, highly susceptible to blast. Molecular analyses on the backcross (BC) lines highlighted the presence of an additional blast-resistance gene, the Pita-linked Pita2/Ptr gene, therefore increasing the number of blast-resistance introgressed genes to five. The recurrent genome was recovered up to 95.65%. Several lines carrying four (including Pita2) Pi genes with high recovery percentage levels were also obtained. Phenotypic evaluations confirmed the effectiveness of the pyramided lines against multivirulent strains, which also had broad patterns of resistance in comparison to those expected based on the pyramided Pi genes. The developed blast-resistant japonica lines represent useful donors of multiple blast-resistance genes for future rice-breeding programs related to the japonica group

Comportement des nouveaux riz africains face à la pyriculariose en Côte d\'Ivoire : cas du Nerica 1 (Bonfani) et du Nerica 2 (Keah).

Les variétés de riz pluvial (oryza glaberrima x Oryza sativa) NERICA1 (Bonfani) et NERICA2 (Kéah), grâce à leur potentiel agronomique, sont en diffusion en Côte d\'Ivoire depuis près de 3 ans. Cela, dans un contexte épidémique marqué par une pression relativement forte de la pyriculariose maladie fongique due à Magnaporthe grisea (Barr, 1977), très préjudiciable au riz Oriza sativa. Dans le but de prévenir d\'éventuelles attaques sévères des NERICA par la maladie, une étude d\'évaluation de leur résistance a été conduite en condition contrôlée. Elle a consisté à confronter par inoculation au stade végétatif (4-5 feuilles), ces variétés de riz à 40 isolats de Magnaporthe grisea, représentatifs de la diversité au sein de la population du parasite en Côte d\'Ivoire. Les résultats des inoculations ont montré une résistance, relativement générale chez NERICA 2 à la pyriculariose, contrairement à NERICA 1 qui a été sévèrement attaqué par certaines souches de la maladie. Ces informations recommandent, au niveau des stratégies de lutte contre la pyriculariose, de privilégier dans les zones à risque, la culture de NERICA 2 au NERICA 1 ou, de cultiver cette dernière variété soit en association, soit en rotation avec le NERICA 2. Par ailleurs, il sera opportun d\'apprécier la réaction du NERICA 1 et du NERICA 2 à la pyriculariose du cou qui à l\'instar de la pyriculariose foliaire, engendre des pertes de récolte souvent importantes sur le riz en Côte d\'Ivoire.NERICA 1 (Bonfani) and NERICA 2 (Kéah) are two upland rice (oryza glaberrima x Oryza sativa) varieties characterized by high yield potentials. For the past three years, these varieties have been extensively used in rice growing regions of Côte d\'Ivoire. Unfortunately, the crop has been subject to omprtant fungus attack. The rice Oriza sativa blast, is caused by a fungus, known as Magnaporthe grisea (Barr, 1977). In order to assess the incidence of the disease on these varieties, an inoculation trial involving 40 isolates, of the pathogen was conducted. NERICA 2 exhibited foliar resistance to all the isolates whereas NERICA 1 was severely attacked. Besides the leaves, the pathogen also affects the neck of the plant which results in important yield losses. Therefore, it would be worthwhile determining the behaviour of the varieties to neck blast. Keywords: Riz, Variétés NERICA, yriculariose, résistance, inoculation, Côte d'Ivoire; Riz, NERICA variety, blast, inoculation, resistance, Côte d'IvoireAgronomie Africaine Vol. 17 (1) 2005: pp. 29-3

Caracterización de cepas de "Magnaporthe oryzae" de distintos hospedantes y virulencia en arroz y trigo

El objetivo fue caracterizar la variabilidad genética de aislamientos de Sudamérica y explorar la patogenicidad de aislamientos de malezas sobre arroz y trigo.EEA Concepción del UruguayFil: Consolo, Verónica Fabiana. Fundación para Investigaciones Biológicas Aplicadas. Centro de Estudios de Biodiversidad y Biotecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Milazzo, J. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; FranciaFil: Adreit, H. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; FranciaFil: Asselborn, Miriam. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; ArgentinaFil: Liberman, Claudia Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; ArgentinaFil: Maumary, Roxana L. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Bonell, Martha Lucrecia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; ArgentinaFil: Tharreau, D. Centre de Coopération Internationale en Recherche Agronomique pour le Développement; FranciaFil: Pedraza, Maria Virginia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Concepción del Uruguay; Argentin

First Report of Black Sigatoka Disease in Bananas Caused by Pseudocercospora fijiensis on Mauritius Island

International audienc

Water management and development: the limits of coordination

International audienceActors involved in water resource management and development policies from the large water cycle (at the river basin level) to the small water cycle (drinking water, sanitation and distribution) are numerous and diversified, in their institutional and economic positioning, as well as in the logic of the approaches they develop. In view of the expectations of a comprehensive policy in this field and of the obviously limited results obtained so far, the phasing of these approaches and the coordination of these actors is a major axis of the actions to be carried out in order to better manage the water resources. We argue the need for an explicit and assumed strengthening of the coordination of water stakeholders at all levels of governance. We question the reasons for these partial successes and failures and the way to overcome these difficulties, questions renewed on the basis of recent experiences. In particular, interdisciplinary and intersectoral collaboration using new hybrid modeling approaches (coupling multi-agent system, geographic information system, equation models, cellular automata, etc.), allows to precisely simulate the scenarios of evolution of water resource management and development, to assess ex ante their social, economic and environmental impacts and to anticipate the contribution of an increased coordination of water stakeholders in a logic of development-friendly actions