Caracterización genética de la resistencia a Meloidogyne incognita de la línea de pimiento P26

Meloidogyne incognita es uno de los principales patógenos del pimiento. En los últimos años las limitaciones en el uso de desinfectantes químicos han motivado el empleo de alternativas, como las resistencias genéticas. Se conocen tres genes mayores de resistencia frente al nematodo (Me1, Me3 y N). Se han encontrado variedades con resistencia parcial de naturaleza genética desconocida, como el caso de la línea P26 y cuya caracterización genética es el objetivo de este trabajo. Para ello P26 se ha cruzado con una línea susceptible (DLL) obteniéndose la F1, F2, y retrocruces BC1 y BC2, y se ha evaluado su nivel de resistencia frente a M. incognita. Los resultados revelan que se trata de una resistencia monogénica, de tipo cuantitativo con efectos aditivos, y con posibles interacciones con otros genes que modifican su expresión.Equipos de Protección de Cultivos y de Horticultura del IMIDA, por su colaboración técnica y la proporción de P26. Dr. Rafael Fernández Muñoz por su asesoramiento en la interpretación de los datos. INIA por la financiación de la beca predoctoral de F. Sánchez‐Solana

Effect of genetic background on resistance to Meloidogyne incognita in pepper

[SPA] En pimiento (Capsicum annuum L.) los genes mayores Me1, Me3 y N confieren resistencia cualitativa frente a M. incognita (principal nematodo patógeno de solanáceas). Sin embargo se han encontrado poblaciones del nematodo virulentas a algunos de estos genes que comprometen la eficacia de estas resistencias. No obstante se ha constatado una mayor durabilidad de estos genes mayores cuando se introgresan en fondos genéticos parcialmente resistentes. El objetivo fue explorar la influencia del fondo genético del pimiento controlando la resistencia parcial cuando se combina con los genes Me1 y Me3, su estabilidad y su modo de herencia. Se utilizaron líneas puras de pimiento susceptibles, parcialmente resistentes y portadoras de Me1 o Me3, y se construyeron diversos híbridos F1. Este material vegetal se testó frente a 3 aislados de M. incognita (dos de éstos virulentos a Me3), y se comparó su nivel de resistencia. Los resultados mostraron diferencias de tipo cuantitativo en la resistencia a M. incognita debidas al efecto del fondo genético, que se expresaron tanto en ausencia como en presencia de genes mayores de resistencia. Esta resistencia cuantitativa se mostró estable frente a los distintos aislados del patógeno y presentó un modo de herencia intermedio. [ENG] In pepper, three major genes –Me1, Me3 and N–confer qualitative resistance against Meloidogyne incognita (main pathogen nematode of Solanaceae). However, nematode virulent populations to some of these genes have been found, threatening the effectiveness of these resistances. Nevertheless higher durability of these major genes has been found when these are introgressed in partially resistant genetic background. The aim was to explore the influence of pepper genetic background controlling partial resistance when combined with Me1 and Me3 genes, its stability and its mode of inheritance. Some pepper inbred lines susceptible, partially resistant or resistant (that carriers Me1 or Me3) were used, and several hybrids F1 were built. This plant material was tested against 3 M. incognita isolates (two virulent to Me3), and their level of resistance was compared. The results showed quantitative differences in resistance to M. incognita due to the effect of genetic background, which was expressed both in presence and absence of qualitative resistance genes. This quantitative resistance was stable against different isolates of the pathogen and presented an intermediate inheritance mode.El equipo de Horticultura (IMIDA) y el Dr. A. Palloix (INRA) proporcionaron el material vegetal. Estudio financiado a través del Proyecto INIA RTA2009-0058 participado con Fondos FEDER. F. Sánchez ha disfrutado de una beca FPI-INIA

Uso reitereado de 1,3-dicloropropeno + cloropicrina en la desinfección de suelos de invernaderos de pimiento

Las mezclas de 1,3-dicloropropeno y cloropicrina se contemplan, a nivel mundial, como la alternativa al bromuro de metilo más asequible a corto plazo, al asociar sustancias con actividad nematicida (1,3 dicloropropeno, 1,3-D) y fungicida (cloropicrina, Pic) (Noling, eta!., 2001; Gilreath, eta!., 2004, 2006) y poderse aplicar por inyección al suelo o en el agua de riego.El trabajo se ha realizado en el marco de las actuaciones del proyecto INIA0T03-006-007-04 y del Programa de Colaboración de la Federación de Cooperativas Agrarias de Murcia y la Consejería de Agricultura y Agua de la Región de Murcia.M.A. Martínez disfruta de una beca predoctoral del INIA

Chitosan Increases Tomato Root Colonization by Pochonia chlamydosporia and Their Combination Reduces Root-Knot Nematode Damage

The use of biological control agents could be a non-chemical alternative for management of Meloidogyne spp. [root-knot nematodes (RKN)], the most damaging plant-parasitic nematodes for horticultural crops worldwide. Pochonia chlamydosporia is a fungal parasite of RKN eggs that can colonize endophytically roots of several cultivated plant species, but in field applications the fungus shows a low persistence and efficiency in RKN management. The combined use of P. chlamydosporia with an enhancer could help its ability to develop in soil and colonize roots, thereby increasing its efficiency against nematodes. Previous work has shown that chitosan enhances P. chlamydosporia sporulation and production of extracellular enzymes, as well as nematode egg parasitism in laboratory bioassays. This work shows that chitosan at low concentrations (up to 0.1 mg ml-1) do not affect the viability and germination of P. chlamydosporia chlamydospores and improves mycelial growth respect to treatments without chitosan. Tomato plants irrigated with chitosan (same dose limit) increased root weight and length after 30 days. Chitosan irrigation increased dry shoot and fresh root weight of tomato plants inoculated with Meloidogyne javanica, root length when they were inoculated with P. chlamydosporia, and dry shoot weight of plants inoculated with both P. chlamydosporia and M. javanica. Chitosan irrigation significantly enhanced root colonization by P. chlamydosporia, but neither nematode infection per plant nor fungal egg parasitism was affected. Tomato plants cultivated in a mid-suppressive (29.3 ± 4.7% RKN egg infection) non-sterilized clay loam soil and irrigated with chitosan had enhanced shoot growth, reduced RKN multiplication, and disease severity. Chitosan irrigation in a highly suppressive (73.7 ± 2.6% RKN egg infection) sterilized-sandy loam soil reduced RKN multiplication in tomato. However, chitosan did not affect disease severity or plant growth irrespective of soil sterilization. Chitosan, at an adequate dose, can be a potential tool for sustainable management of RKN.This research was funded by two grants from the Spanish Ministry of Economy and Competitiveness (AGL 2013-49040-C2-1-R and AGL2015-66833-R,) and by a Ph.D. fellowship from the University of Alicante to NE (UAFPU2011). Part of this work was filed for a patent (P201431399) by LL-L, FL-M, and NE as inventors

Influencia del humedecimiento del suelo previo a la aplicación del telone C-35 sobre la eficacia de la desinfección del suelo de invernaderos de pimiento

El Telone C-35 EC (1,3 dicloropropeno 60,3% + cloropicrina 32,3%), aplicado en el agua de riego, se presenta como una alternativa viable al uso del bromuro de metilo (BrMe) en la desinfección de suelos de invernaderos de pimiento

Chitosan increases tomato root colonization by Pochonia chlamydosporia and their combination reduces Root-Knot nematode damage

The use of biological control agents could be a non-chemical alternative for management of Meloidogyne spp. [root-knot nematodes (RKN)], the most damaging plant-parasitic nematodes for horticultural crops worldwide. Pochonia chlamydosporia is a fungal parasite of RKN eggs that can colonize endophytically roots of several cultivated plant species, but in field applications the fungus shows a low persistence and efficiency in RKN management. The combined use of P. chlamydosporia with an enhancer could help its ability to develop in soil and colonize roots, thereby increasing its efficiency against nematodes. Previous work has shown that chitosan enhances P. chlamydosporia sporulation and production of extracellular enzymes, as well as nematode egg parasitism in laboratory bioassays. This work shows that chitosan at low concentrations (up to 0.1 mg ml-1) do not affect the viability and germination of P. chlamydosporia chlamydospores and improves mycelial growth respect to treatments without chitosan. Tomato plants irrigated with chitosan (same dose limit) increased root weight and length after 30 days. Chitosan irrigation increased dry shoot and fresh root weight of tomato plants inoculated with Meloidogyne javanica, root length when they were inoculated with P. chlamydosporia, and dry shoot weight of plants inoculated with both P. chlamydosporia and M. javanica. Chitosan irrigation significantly enhanced root colonization by P. chlamydosporia, but neither nematode infection per plant nor fungal egg parasitism was affected. Tomato plants cultivated in a mid-suppressive (29.3 ± 4.7% RKN egg infection) non-sterilized clay loam soil and irrigated with chitosan had enhanced shoot growth, reduced RKN multiplication, and disease severity. Chitosan irrigation in a highly suppressive (73.7 ± 2.6% RKN egg infection) sterilized-sandy loam soil reduced RKN multiplication in tomato. However, chitosan did not affect disease severity or plant growth irrespective of soil sterilization. Chitosan, at an adequate dose, can be a potential tool for sustainable management of RKN