Caracterización morfológica, molecular y fisiológica del sistema Colletotrichum/Glomerella – Glycine max y su relación biológico epidemiológica con otros hospedantes en la zona productora núcleo de Argentina
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Date
2020
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FCA-UNR
Abstract
Las enfermedades constituyen un factor limitante para la producción vegetal tanto en el
rendimiento como en la calidad de la semilla de cereales y oleaginosos. La antracnosis es una
enfermedad asociada al cultivo de soja y maíz, causada por las especies de hongos que conforman
un complejo conocido como enfermedades de fin de ciclo (EFC). El complejo fúngico
Glomerella/Colletotrichum (G/C) es un binomio constituido por un Ascomycota (fase sexual,
perfecta o teleomorfo) y un Deuteromycota (fase asexual, imperfecta o anamorfo), que causa
antracnosis en diversas especies vegetales de las familias Fabaceae, Poaceae, Solanaceae y
Rosaceae. Este complejo G/C muestra amplia variabilidad genética y especificidad fisiológica
al interactuar con diferentes genotipos de un mismo y/o diferentes hospedantes. Los objetivos
del trabajo fueron a)Validar morfológica y molecularmente las identidades de la colección de
aislados del complejo G/C obtenidos en plantas sintomáticas de diferentes familias y especies de
hospedantes y diversos ambientes de la zona núcleo; b) Caracterizar el comportamiento
(avirulencia/virulencia) de los diversos aislados del complejo fúngico y la reacción
(resistencia/susceptibilidad) de los hospedantes en base a la observación fenotípica e identificar
fuentes de resistencia a la enfermedad en los cultivos evaluados y c) Evaluar el complejo G/Cy
sus interacciones bajo condiciones seminaturales en una rotación soja – maíz. Durante dos ciclos
agrícolas, se evaluaron las asociaciones resultantes de la interacción de 3 genotipos de soja y 5
híbridos de maíz con 6 aislados G/C obtenidos de tallos sintomáticos de ambos cultivos y de
cítricos, provenientes de las provincias de Santa. Fe, Buenos Aires, Córdoba y Entre Ríos. La
identidad fue propuesta por macro y micromorfología y validada molecularmente por RAPDs y
secuenciación de amplicones de ITs. Las inoculaciones en soja se realizaron por herida en el
estado fenológico de V3. Las evaluaciones se realizaron según los parámetros de Incidencia (IE)
y Severidad de entrenudos (SE). Las inoculaciones en maíz se realizaron con jeringa en el estado
Vt y R1. Se evaluó IE % y SE % cada 10 días posterior a la inoculación hasta finalizar el ciclo del cultivo. En ambos cultivos (soja y maíz) se pudo determinar una Escala de 5 grados para
cuantificar severidad de antracnosis en entrenudos. Tanto los cultivares de soja como los de maíz
mostraron diferencias en su respuesta de resistencia y susceptibilidad, expresados en IE y SE
promedio frente al patógeno, y se detectaron además interacciones específicas significativas. Los
aislados de C. truncatum y C. gloeosporioides provenientes de cultivos de soja y de mandarina
fueron los más virulentos en las inoculaciones de maíz. Mientras en soja, las cepas de C.
graminicola, C. gloeosporioides y C. truncatum resultaron virulentas según la severidad de
antracnosis en los entrenudos. Las infecciones se produjeron con mayor severidad en el segundo
entrenudo avanzado hacia el ápice y hacia la base. Para el cumplimiento del tercer objetivo se
realizó un ensayo en parcelas bajo cubierta antigranizo, simulando condiciones naturales, donde
se sembraron los tres genotipos de soja sobre rastrojo de maíz infectado independientemente con
cinco cepas de G/C provenientes de hospedantes maíz y soja. Estos resultados mostraron que los
genotipos de soja se infectaron y expresaron síntomas de antracnosis causadas por aislados de
diferentes hospedantes y zonas agroecológicas, registrándose diferencias significativas en todas
las interacciones. En este sistema de rotación maíz – soja (ambos hospedantes de G/C), el rastrojo
de maíz infectado de antracnosis resultó efectivo como fuente de inóculo primario de C.
graminicola, C. truncatum y C. gloeosporioides e iniciar un proceso patógenico en los genotipos
de soja. Demostrando un riesgo epidemiológico para un sistema productivo basado en la
alternancia de cereales y oleaginosos, implementado y generalizado entre los productores de la
región centro. Por ello, la determinación de genotipos de soja y maíz con respuestas diferenciales
(R, MR/MS y S) frente a diferentes cepas del patógeno, permitirá su incorporación en futuros
programas de mejoramiento.
Glycine max y su relación bio-epidemiológica con otros hospedantes en la zona productora núcleo de Argentina. Diseases constitute a limiting factor for plant production, both in the yield and quality of cereal and oilseed seeds. Anthracnose is a disease associated with the cultivation of soybeans and corn, caused by the species of fungi that make up a complex known as end-of-cycle diseases (CFEs). The Glomerella / Colletotrichum (G/C) fungal complex is a binomial consisting of an Ascomycota (sexual, perfect or teleomorphic phase) and a Deuteromycota (asexual, imperfect or anamorphic phase), which causes anthracnose in various plant species of the Fabaceae families, Poaceae, Solanaceae and Rosaceae. This G/C complex shows wide genetic variability and physiological specificity when interacting with different genotypes of the same and / or different hosts. The objectives of the work were a) To validate morphologically and molecularly the identities of the collection of isolates of the G/C complex in symptomatic plants of different host families and species and various environments of the core zone; b) Characterize the behavior (avirulence / virulence) of the various isolates of the fungal complex and the reaction (resistance / susceptibility) of the hosts based on phenotypic observation and identify sources of resistance to the disease in the evaluated crops and c) Evaluate the G/C complex and its interactions under semi-natural conditions in a soybean-corn rotation. During two agricultural cycles, the associations resulting from the interaction of 3 soybean genotypes and 5 maize hybrids with 6 G/C isolates obtened from symptomatic stems of both crops and citrus fruits from the Santa Fe, Buenos Aires, Córdoba and Entre Ríos provinces, were evaluated. The identity was proposed by macro and micro-morphology and molecularly validated by RAPDs and ITS amplicon sequencing. Soybean inoculations were performed by wound in the phenological state of V3. The evaluations were carried out according to the Incidence (IE) and Internode Severity (SE) parameters. Corn inoculations were performed with a syringe in the Vt and R1 state. IE% and SE% were evaluated every 10 days after inoculation until the end of the cultivation cycle. In both crops (soybeans and corn), a 5-degree Scale could be determined to quantify anthracnose severity in internodes. Both soybean and corn cultivars showed differences in their resistance and susceptibility response, expressed in average IE and SE against the pathogen, and significant specific interactions were also detected. Isolates of C. truncatum and C. gloeosporioides from soybean and mandarin crops were the most virulent in maize inoculations. While in soybeans, the strains of C. graminicola and C. gloeosporioides and C. truncatum were virulent according to the severity of anthracnose in the internodes. Infections occurred more severely in the second internode advanced towards the apex and towards the base. To fulfill the third objective, a trial was carried out in plots under hail cover, simulating natural conditions, where the 3 soybean genotypes were planted on corn stubble independently infected with 5 G / C strains from corn and soybean hosts. The results showed that soybean genotypes were infected and expressed anthracnose symptoms caused by isolates from different hosts and agro-ecological zones, registering significant differences in all interactions. In this corn-soybean rotation system (both G/C hosts), anthracnose-infected corn stubble was effective as a source of primary inoculum for C. graminicola, C. truncatum and C. gloeosporioides and to start a pathogenic process in the soybean genotypes. Demonstrating an epidemiological risk for a production system based on the alternation of cereals and oilseeds, implemented and widespread among producers in the central region. Therefore, the determination of soybean and corn genotypes with differential responses (R, MR / MS and S) against different strains of the pathogen, will allow their incorporation in future breeding programs.
Glycine max y su relación bio-epidemiológica con otros hospedantes en la zona productora núcleo de Argentina. Diseases constitute a limiting factor for plant production, both in the yield and quality of cereal and oilseed seeds. Anthracnose is a disease associated with the cultivation of soybeans and corn, caused by the species of fungi that make up a complex known as end-of-cycle diseases (CFEs). The Glomerella / Colletotrichum (G/C) fungal complex is a binomial consisting of an Ascomycota (sexual, perfect or teleomorphic phase) and a Deuteromycota (asexual, imperfect or anamorphic phase), which causes anthracnose in various plant species of the Fabaceae families, Poaceae, Solanaceae and Rosaceae. This G/C complex shows wide genetic variability and physiological specificity when interacting with different genotypes of the same and / or different hosts. The objectives of the work were a) To validate morphologically and molecularly the identities of the collection of isolates of the G/C complex in symptomatic plants of different host families and species and various environments of the core zone; b) Characterize the behavior (avirulence / virulence) of the various isolates of the fungal complex and the reaction (resistance / susceptibility) of the hosts based on phenotypic observation and identify sources of resistance to the disease in the evaluated crops and c) Evaluate the G/C complex and its interactions under semi-natural conditions in a soybean-corn rotation. During two agricultural cycles, the associations resulting from the interaction of 3 soybean genotypes and 5 maize hybrids with 6 G/C isolates obtened from symptomatic stems of both crops and citrus fruits from the Santa Fe, Buenos Aires, Córdoba and Entre Ríos provinces, were evaluated. The identity was proposed by macro and micro-morphology and molecularly validated by RAPDs and ITS amplicon sequencing. Soybean inoculations were performed by wound in the phenological state of V3. The evaluations were carried out according to the Incidence (IE) and Internode Severity (SE) parameters. Corn inoculations were performed with a syringe in the Vt and R1 state. IE% and SE% were evaluated every 10 days after inoculation until the end of the cultivation cycle. In both crops (soybeans and corn), a 5-degree Scale could be determined to quantify anthracnose severity in internodes. Both soybean and corn cultivars showed differences in their resistance and susceptibility response, expressed in average IE and SE against the pathogen, and significant specific interactions were also detected. Isolates of C. truncatum and C. gloeosporioides from soybean and mandarin crops were the most virulent in maize inoculations. While in soybeans, the strains of C. graminicola and C. gloeosporioides and C. truncatum were virulent according to the severity of anthracnose in the internodes. Infections occurred more severely in the second internode advanced towards the apex and towards the base. To fulfill the third objective, a trial was carried out in plots under hail cover, simulating natural conditions, where the 3 soybean genotypes were planted on corn stubble independently infected with 5 G / C strains from corn and soybean hosts. The results showed that soybean genotypes were infected and expressed anthracnose symptoms caused by isolates from different hosts and agro-ecological zones, registering significant differences in all interactions. In this corn-soybean rotation system (both G/C hosts), anthracnose-infected corn stubble was effective as a source of primary inoculum for C. graminicola, C. truncatum and C. gloeosporioides and to start a pathogenic process in the soybean genotypes. Demonstrating an epidemiological risk for a production system based on the alternation of cereals and oilseeds, implemented and widespread among producers in the central region. Therefore, the determination of soybean and corn genotypes with differential responses (R, MR / MS and S) against different strains of the pathogen, will allow their incorporation in future breeding programs.
Description
Keywords
Maíz, Soja, Collectotrichum spp, Antracnosis, Interaciones Planta Patógeno