Petra Andrade-Hoyos

Objetivo. Identificar germoplasma de arroz resistente a Burkholderia glumae para desarrollar variabilidad genética que dé origen a nuevas variedades de arroz con resistencia al tizón de la panícula del arroz causado por esta bacteria. Materiales y métodos. En 2023 se evaluaron 230 genotipos del banco nacional de germoplasma de arroz del INIFAP, los cuales se inocularon en la etapa fenológica 4 y 5 mediante inyección de 0.5 mL de la solución bacteriana (1 x 107 UFC/mL) durante la etapa fenológica 4 y 5, con una cepa de B. glumae (registrada en el Genbank con número de accesión PV210103.1); previamente, en el invernadero del Campo Experimental Zacatepec, Morelos, dos semillas de cada uno de los 230 genotipos de arroz fueron sembradas en macetas usando un diseño experimental completamente al azar con tres repeticiones. Para sustentar los resultados se registró el porcentaje de grano vano y la severidad causada por la bacteria inoculada. Resultados. De la evaluación de los 230 genotipos de arroz, tres resultaron con resistencia a B. glumae (R):WAB45024-2-3P33HB, Orona A17 y FL02768-2P-6-4P-1P-M-1P, y 13 con moderada resistencia (MR). Conclusiones. Los materiales que resultaron resistentes a la cepa de B. glumae servirán como padres donadores de resistencia a B. glumae PV210103.1.

Resumen. Mortalidad del Picudo del Nopal Metamasisus spinolae1 Con la AplicaciÓN de Heterorhabditis bacteriophora2 JAAN-19 Se evaluó el nematodo Heterorhabditis bacteriophora (Poinar) JAAN-19 como agente de control biológico de Metamasius spinolae. In vitro, una concentración de 1000 Jl/picudo produjo una mortalidad de 90% tan-to en hembras como en machos en seis días después de la aplicación, lo que demostró la capacidad de búsqueda e infección del nematodo, alcanzando una mortalidad de 97% en un tiempo a los 8 días. La dosis letal (LD50) se calculó en 138 JI/picudo y la LD90 463 JI/picudo después de los 6 días. Estos resultados demuestran que H. bacteriophora JAAN-19 es un controlador de M. spinolae.

Cinnamon is a tree introduced to the lowlands of Mexico in the mid-16th century, but it spread to other places at the beginning of the 20th century due to its important commercial value as an aromatic spice. In the state of Veracruz, symptoms of dieback have been observed in 12-year-old cinnamon plantations cultivated in an agroforestry system, causing concern among producers. For this reason, the present investigation was carried out to determine the causal agent of these symptoms observed in cinnamon trees. Fifty symptomatic plants were recovered from established plantations. One hundred cinnamon root fragments showing dieback were selected and separated; isolates were made from tissue showing crown and root rot on clarified juice V-8 agar medium. After eight days, the growth of whitish coralloid mycelium with characteristics similar to the Phytophthora oomycete was consistently observed. Subsequently, the identity corresponding to P. cinnamomi was confirmed by morphological, taxonomic studies and Bayesian inference of the rDNA internal transcribed spacer. The pathogenicity test was performed on 20 6-month-old cinnamon plants grown in pots by inoculating 2.5 × 10⁴/mL of zoospores around the roots. Control plants were inoculated with sterile distilled water and kept in a greenhouse under conditions controlled. After five weeks, symptoms of root rot were observed in the inoculated plants; however, the control group plants remained healthy. The results showed that P. cinnamomi subclade 7c was responsible for the symptoms observed in lowland cinnamon plantations in Mexico. Our findings suggest that this phytopathogen is a new threat for cinnamon growers; likewise, it is recommended that growers implement management strategies to avoid its introduction into nurseries or new plantations that could be susceptible to this pathogen.