Bacillus is one of the main rhizobacteria to have been used as a study model for understanding many processes. However, their impact on photosynthetic metabolism has been poorly studied. The aim of this study was to evaluate the physiological parameters of pepper (Capsicum chinense Jacq.) plants inoculated with Bacillus spp. strains. Pepper seeds were inoculated with Bacillus cereus (K46 strain) and Bacillus spp. (M9 strain; a mixture of B. subtilis and B. amyloliquefaciens), chlorophyll fluorescence and gas exchange were evaluated. The ANOVA (P ≤ 0.05) showed that the maximum photochemical quantum yield of photosystem II (PSII) (F v /F m ) in plants inoculated with the M9 strain (0.784) increased with respect to other treatments (K46: 0.744 and Control: 0.739). Inoculated plants with M9 and K46 strains exhibited an increase of both photochemical quenching (qP) (by 27% and 24%, respectively) and CO 2 assimilation rate (photosynthesis) (by 20% and 16%, respectively), when compared with non-inoculated plants. Furthermore, plants inoculated with M9 and K46 showed decreased transpiration (61% and 57%, respectively) with respect to controls. Likewise, both electron transport rate of PSII (ETR) and PSII operating efficiency (Φ PSII ) increased in inoculated plants. However, only plants inoculated with the M9 strain showed enhancements on all growth characteristics. Our results therefore show that inoculating plants with M9 strain positively influenced the performance of the photosynthetic mechanism in pepper plants to increase chlorophyll fluorescence and gas exchange parameters. Promotion of photosynthetic capacity in pepper was due to increased ETR in the thylakoid membranes, which was promoted by the bacteria. M9 strain could even be used in sustainable agriculture programs.

Resumen. El género Fusarium es un patógeno asociado al marchitamiento del chile y con reducción del rendimiento del cultivo. Las rizobacterias son una alternativa para mejorar la producción agrícola y protección contra fitopatógenos. En el presente estudio se evaluó el antagonismo in vitro de diez cepas de Bacillus contra Fusarium equiseti ITCF1 y F. solani ITCF2, todas la cepas bacterianas inhibieron el crecimiento micelial entre 21.28 y 71.70 %, adicionalmente las cepas CBMT2 y CBMT51 presentaron halos de inhibición contra F. equiseti con halos de 3.76 y 6.37 mm.

Trichoderma spp. se utilizan como método de biocontrol de fitopatógenos causantes de pérdidas agrícolas. El objetivo de este trabajo fue identificar nueve cepas de Trichoderma, determinar la capacidad an- tagónica contra Fusarium oxysporum y Corynespora cassiicola, así como los genes que codifican los elicitores Sm1 y Epl1 de la resistencia sistémica en plantas. La capacidad antagónica contra fitopatógenos se determinó mediante enfrentamientos duales. La identificación molecular correspondió a T. asperellum (19-31), T. erinaceum (10-15), T. ghanense (21-39) y T. harzianum (18-31, 05E-60, 20-35, 13-01, 01-01, 29-54). Las cepas, 10-15, 19-31 y 05E-60 presentaron mayor capacidad de inhibición micelial contra F. oxysporum, mientras las cepas 32-09 y 27-08 contra C. cassiicola. Los metabolitos volátiles de las cepas 27-08, 21-39 y 05E-60 inhibieron el crecimiento de F. oxysporum. La presencia de los genes Epl1 fueron identificados en las cepas 19-31 y 10-15, y Sm1 en las cepas 27-08 y 32-09.

The aim of this study was to evaluate the effect of inoculation with Bacillus spp. isolates on the photosynthetic apparatus of Capsicum chinense plants infected with PepGMV. In vitro and greenhouse experiments were performed to evaluate whether the inoculation improved plants’ performance through the increase in photosynthetic efficiency to control PepGMV. The results showed that despite PepGMV infection, the plants inoculated with some isolates of Bacillus spp. had a healthy photosynthetic mechanism, as the photochemical parameters and gas exchange increased. The maximum photochemical quantum yield of PSII (Fv/Fm) of plants with PepGMV and inoculated with Bacillus isolates (M9, K46, and K47) increased (7.85, 7.09, and 7.77%, respectively) with respect to uninoculated controls. In inoculated plants, the CO2 assimilation rate increased and the transpiration rate decreased, therefore indicating an increased water use efficiency. This effect was reflected by the less severe symptoms caused by PepGMV in the plants obtained from seeds inoculated with different Bacillus spp. Plants inoculated with K47 isolates showed an increase in fruit yield and quality. This study suggests that it is possible to protect, at the greenhouse level, C. chinense plants from PepGMV through selected rhizobacteria inoculation.

No abstract

No abstract

En áreas tropicales se conoce poco sobre la diversidad de parasitoides, especialmente en cultivos; donde se ha demostrado que estos insectos son sensibles al aumento de la superficie agrícola. El objetivo del trabajo fue evaluar la diversidad y composición de especies de parasitoides en cultivos de maíz de diferente superficie con selva baja caducifolia circundante. Se colocaron seis trampas Malaise: dos en un cultivo de maíz de 10 ha, dos en maíz de 50 ha y dos en selva, que funcionaron durante el ciclo fenológico del maíz, en las que se realizaron colectas semanales. Se recolectaron 1 149 individuos, que representan 43 géneros de los que 21 son nuevos registros para el estado de Campeche, México. No se encontraron diferencias en el número de géneros presentes en los sitios y la composición de comunidades fue similar, lo que refleja la migración de géneros entre la selva y los agroecosistemas; pero si presentaron diferencias en los géneros dominantes, lo que sugiere que los parasitoides responden al hábitat. Se encontraron siete gremios de parasitoides, dominando los parasitoides que atacan fitófagos ocultos. La diversidad de géneros fue similar entre la selva y maíz de 50 ha, la diversidad de gremios se relaciona con el tamaño del hábitat, áreas de mayor tamaño, tienen mayor biodiversidad. Los géneros que dominaron las comunidades fueron Eiphosoma, Pristomerus, Microcharops y Casinaria, los cuales, con excepción del último, han sido registrados como controladores biológicos de Spodoptera frugiperda en maíz.

Corynespora cassiicola is a pathogen that causes lesions in different organs of tomato crops. For its control, synthetic fungicides are used that require more than one application. Trichoderma spp. is a highly interactive saprophytic fungus in the rhizosphere known as a biological control agent against plant diseases and promoter of plant growth due to its different modes of action. The effect on physiological and growth variables in Solanum lycopersicum plants inoculated with spore concentrations 1x100, 1x105, 1x106, 1x107 and 1x108 of Trichoderma asperellum Ta-13-17 and Fithan®, (as a commercial control) was evaluated. As a biocontrol agent for C. cassiicola under protected conditions. The 1x106, 1x108 and Fithan® treatments obtained the highest photosynthetic rates with 20.7, 20.6 and 19.6 µmol m-2 s-1 respectively. The 1x108 conidia mL-1 treatment obtained the highest means in the photosynthesis variables 20.6 µmol m-2 s-1, yield 1347.02 g per plant and presented a lower percentage of final severity, lower speed in the distribution of the disease and lower accumulation of area under the disease progress curve.