The Extraordinary Nature of RNA Interference in Understanding Gene Downregulation Mechanism in Plants

Gene silencing (also known as ribonucleic acid [RNA] interference [RNAi] or interfering RNA) was first recognized in plants and is considered one of the most significant discoveries in molecular biology in the last several years. These short-chain ribonucleic acid molecules regulate eukaryotic gene expression. The phenomenon involves a process that promotes RNA transcripts degradation through complementarity between RNA molecules and RNAi transcripts, resulting in the reduction of their translation levels. There are two principal classes of regulatory RNA molecules: small interfering RNAs (siRNA) and microRNAs (miRNA). Both are generated from the cleavage of double-stranded self-complementary RNA hairpins by a DICER enzyme that belongs to the RNase III family. Small RNAs (of about 21–24 nucleotides in size) guide specific effector Argonaute protein to a target nucleotide sequence by complementary base pairing. Thereby, the effector protein complex downregulates the expression of RNA or DNA targets. In plants, cis-regulatory RNAi sequences are involved in defense mechanisms against antagonistic organisms and transposition events, while trans-regulatory sequences participate in growth-related gene expression. siRNA also performs neutral antiviral defense mechanisms and adaptive stress responses. This document is an attempt to scrutinize the RNAi nature in understanding gene downregulation mechanism in plants and some technical applications

Physical and chemical properties of soils irrigated with vinasses for the cultivation of sugarcane (Saccharum spp.) in the central region of Veracruz, Mexico

Objective: To evaluate the physical and chemical properties of a soil with vinasse application (two years) (V), compared to a soil without vinasse (W/V). Design/methodology/approach: In both agroecosystems, the evaluated parameters were texture, pH, electrical conductivity (EC), organic matter (OM), phosphorus (P), potassium (K), nitrates (NO3) and total nitrogen (TN) according to standardized methods in NOM-021-SEMARNAT-2000. Results: There were no significant changes (p>0.05) in the pH and electrical conductivity, however, the application of vinasse significantly increased (p˂0.05) the content of TN (1.52%), K (112.00 mg L-1) and OM (4.52%) in relation to soils W/V (0.78%, 25.60 mg L-1, 7.40 mg L-1, 2.75%, respectively). Limitations on study/implications: In Veracruz state, there are few studies that allow knowing the contributions, and physical and chemical effects on soils irrigated with vinasses. Findings/conclusions: Even though, the vinasse used showed a positive effect on the physical and chemical characteristics of the soil (V), the mineral fertilization program must be reformulated to increase the concentration of potassium and phosphorus in soils with silt loam texture. In addition, it is recommended to adjust and normalize the dose of N that vinasse can provide instead of conventional fertilizers. Keywords: Soil fertility, sugarcane, vinasses.Objective: To evaluate the physical and chemical properties of a soil irrigated with vinasse for two years (+V), compared with a soil without vinasse (-V) application.Design/Methodology/Approach: The following parameters were evaluated for both agroecosystems: texture, pH, electrical conductivity (EC), organic matter (OM), phosphorus (P), potassium (K), nitrate (NO 3 ), and total nitrogen (TN). The evaluation followed the standardized methods established in NOM-021-SEMARNAT-2000.Results: There were no significant changes (p > 0.05) in the soil’s pH and electrical conductivity. However, the application of vinasse significantly increased (p < 0.05) the concentrations of TN (1.52%), K (112.00 mg L -1 ), and OM (4.52%) in relation to soils - V (0.78%, 25.60 mg L -1 , 7.40 mg L-1 , and 2.75%, respectively). Study Limitations/Implications: There are few studies about the contributions and the physical and chemical effects of soil irrigation with vinasses in the State of Veracruz.Findings/Conclusions: Even though vinasse had a positive effect on the physical and chemical characteristics of the soil, the mineral fertilization program must be reformulated to increase the K and P concentration in soils with silt loam texture. In addition, we recommend adjusting and normalizing the dose of N that vinasse can provide to complement conventional fertilizers

Oribátidos, colémbolos y hormigas como indicadores de perturbación del suelo en sistemas de producción agrícola

The abundance, richness and diversity of oribatids, collembola and ants were compared as indicators of soil disturbance found under (traditional) minimal management systems, transition management and technified handling of the mango crop, as well as in the technified management system of sugarcane in the Central Veracruz region in Mexico. In each management system, soil and litter samples were taken, in which arthropods were collected using the Berlese-Tullgren funnels method. The samplings were carried out in three seasons of the spring, summer and winter for 2017 and 2018. The most abundant species were the mites Ceratozetes sp., Archegozetes longisetosus, Scheloribates laticlava, Paropanolophus sp. and Pseudoparasitus sp., Collembola Pseudosinella sp. and Seira sp., and the ants Solenopsis conjurata, Solenopsis terricola, Pyramica brevicornis and Pachycondyla harpax. Colémbolos and ants were more abundant under the mínimum management system followed by management in transition, and finally in the systems of technified management of mango and sugarcane. On the other hand, the oribatids were more abundant in the management system of mango cultivation. The management system technified with sugar cane had an average of 12.3 individuals, 1.3 species and amount of 0.26 diversity, which was significantly lower than the other systems (abundance, F3,112 = 7.2, p = 0.0001, richness, F3,112 = 13.3, p = 0.0001, diversity, F3,112 = 13.2, p = 0.0001), which did not show significant differences among themselves (p > 0.05).Se comparó la abundancia, riqueza y diversidad de oribátidos, colémbolos y hormigas como indicadores de perturbación del suelo encontrados bajo sistemas de manejo mínimo (tradicional), manejo en transición y manejo tecnificado del cultivo de mango, así como el sistema de manejo tecnificado de la caña de azúcar en la región Centro de Veracruz, México. En cada sistema de manejo se tomaron muestras de suelo y hojarasca, para colectar artrópodos mediante el método de embudos de Berlese-Tullgren. Los muestreos se realizaron en primavera, verano e invierno durante el 2017 y 2018. Las especies con mayor abundancia fueron los ácaros Ceratozetes sp., Archegozetes longisetosus, Scheloribates laticlava, Paropanolophus sp. y Pseudoparasitus sp., los colémbolos Pseudosinella sp. y Seira sp., y las hormigas Solenopsis conjurata, https://www.facebook.com/isastoppr/videos/2280266608886864colémbolos y hormigas fueron más abundantes bajo el sistema de manejo mínimo seguido por manejo en transición, y por último en los sistemas de manejo tecnificado de mango y caña de azúcar. En cambio, los oribátidos fueron más abundantes en el sistema de manejo tecnificado del cultivo de mango. El sistema de manejo tecnificado con caña de azúcar con promedio de 12.3 individuos, 1.3 especies y 0.26 de diversidad fue significativamente inferior a los otros sistemas (abundancia, F3,112 = 7.2, p = 0.0001; riqueza, F3,112 = 13.3, p = 0.0001; diversidad, F3,112 = 13.2, p = 0.0001), los cuales no presentaron diferencias significativas entre sí (p >0.05)

Fauna y microflora edáfica asociada a diferentes usos de suelo

In order to evaluate the effects of land use with sugarcane and grasses on macrofauna, mesofauna and microflora in the municipality of Úrsulo Galván, Veracruz, we compared the abundance, richness and diversity of groups of organisms in soil with sugarcane, grass and native vegetation typical of the region. Soil samples were taken from a 25 x 25 cm quadrant at a depth of 0-30 cm, from which soil fauna and microflora were extracted to identify and quantify them. Results indicate that soil with sugarcane was less harmful to soil fauna (9 taxa and 305 individuals) than soil with grass (6 taxa and 91 individuals) and that it was not statistically different from soil with native vegetation (9 taxa and 357 individuals). The abundance of most of the macro and mesofauna groups corresponded to soil with native vegetation (Aranea, Formicidae, Diplopoda and Oligochaeta) and with sugarcane (Isoptera, Chilopoda y Diplura). In the dry season, soil with sugarcane recorded the highest abundance of phosphorus-solubilizing and nitrogen-fixing bacteria (12333 cfu and 9465 cfu, respectively) compared to soil with native vegetation (4840 cfc and 5774 cfu, respectively). Only the soil covered with sugarcane has no effect on the soil’s microbial flora and fauna.Con el objetivo de evaluar los efectos del uso de suelo con caña de azúcar y pastos, sobre la macrofauna, mesofauna y microflora en el municipio de Úrsulo Galván, Veracruz, se comparó la abundancia, riqueza y diversidad de grupos de organismos en suelo con caña, pasto y vegetación nativa típica de la región.Se utilizaron muestras de suelo tomadas con un cuadrante de 25 x 25 cm a profundidad de 0-30 cm, de los que se extrajo la fauna y microflora edáfica, para identificarla y cuantificarla. Los resultados indican que el suelo con caña de azúcar fue menos nocivo para la fauna edáfica (9 taxones y 305 individuos) que el suelo con pasto (6 taxones y 91 individuos) y que no fue diferente estadísticamente con el suelo con vegetación nativa (9 taxones y 357 individuos). La abundancia de la mayoría de los grupos de macro y mesofauna correspondieron a suelo con vegetación nativa (Aranea, Formicidae, Diplopoda y Oligochaeta) y con caña de azúcar (Isoptera, Chilopoda y Diplura). En la época de secas, el suelo con caña de azúcar registró la mayor abundancia de bacterias solubilizadoras de fósforo y fijadoras de nitrógeno (12333 ufc y 9465 ufc, respectivamente) en comparación con el suelo con vegetación nativa (4840 ufc y 5774 ufc, respectivamente). Únicamente el suelo cubierto con caña de azúcar tiene nula afectación sobre la fauna y flora microbiana del suelo

BIOSTIMULANTS AND BIORATIONAL INSECTICIDES IN THE CULTIVATION OF EGGPLANT IN PROTECTED CONDITIONS OF MACRO TUNNELS

Background. Microbial biostimulants in plants allow to improve nutrition and quality in crop fruits. Insecticides based on entomopathogenic fungi and state-of-the-art insecticides control pests in vegetables effectively. Objective. To evaluate three biostimulants and three biorational insecticides in eggplant cultivation under macrotunnel protected conditions. Methodology. The biostimulant treatments were: Genifix®, T22®, Mix® and control; for insecticides were: Movento®, Beauveria bassiana, Isaria javanica and control. They were evaluated in eggplant under macrotunnel conditions. Results. There was a significant effect of biostimulants on the increase in weight and dimensions of eggplant fruits, highlighting Genifix®, followed by T22® and Mix®. Movento® reduced more whiteflies compared to B. bassiana and I. javanica. Implications. The evaluated products can be applied in a biorational management of eggplant, reducing the excessive use of synthetic fertilizers and insecticides. Conclusions. The potential of the biostimulant Genifix®, T22® and Mix® to improve the development of eggplant fruits was demonstrated, as well as the insecticide Movento® to control the pest Bemisia tabaci in eggplant. The bioinsecticide B. bassiana can be used effectively in integrated management of whitefly in eggplant

Fauna edáfica e insectos asociados a las arvenses en limón persa, monocultivo y policultivo

Abstract. The state of Veracruz, Mexico, has a productive potential under the monoculture system, but there are environmental problems and agricultural pests. Faced with this situation, alternatives are being sought to develop more sustainable agroecosystems, such as diversified plots or intercropping. Therefore, the objective of the work was to compare the abundance, richness, diversity and equity of edaphic fauna and insects associated with arvences in the cultivation of persian lemon in monoculture and in polyculture in the central coastal region of Veracruz, Mexico. Monoculture plots (persian lemon only) and polyculture plots (persian lemon, banana and cocoa) were evaluated. Three plots were located: 1 = monoculture at a distance of 250 m from the plot in polyculture, 2 = monoculture at a distance of 100 m from the plot in polyculture and 3 = plot in polyculture. Ecological indices of abundance, richness, diversity, equity, and similarity of organisms in each of the plots were calculated. For the edaphic fauna, the polyculture plot had the highest diversity and equity and was significantly different from the monoculture plots; the monoculture plots were more similar to each other than with the poly- culture plot. For insects associated with arvences, the polyculture plot had greater diversity and equity, in addition to being significantly different from the most remote monoculture plot, but not to the closest one, the polyculture plot shared the greatest similarity of insects with the monoculture plot closest to this.Resumen. El estado de Veracruz, México, cuenta con un potencial productivo bajo el sistema de monocultivos, pero se tienen problemas ambientales y de plagas agrícolas. Ante esta situación, se están buscando alternativas para desarrollar agroecosistemas sostenibles, como las parcelas diversificadas o cultivos intercalados. Por lo anterior, el objetivo del trabajo fue comparar la abundancia, riqueza, diversidad y equidad de fauna edáfica e insectos asociados a las arvenses en el cultivo de limón persa en monocultivo y policultivo en la región centro costera del estado de Veracruz, México. Se evaluaron parcelas en monocultivo (solo limón persa) y parcelas en policultivo (limón persa, plátano y cacao). Se ubicaron tres parcelas: 1 = monocultivo a distancia de 250 m de la parcela en policultivo, 2 = monocultivo a distancia de 100 m de la parcela en policultivo y 3 = parcela en policultivo. Se calcularon los índices ecológicos de abundancia, riqueza, diversidad, equidad y similaridad de organismos en cada una de las parcelas. Para la fauna edáfica, la parcela en policultivo tuvo la mayor diversidad y equidad y fue significativamente diferente a las parcelas en monocultivo, las parcelas en monocultivo fueron más similares entre sí que con la parcela en policultivo. Para insectos asociados a las arvenses, la parcela en policultivo tuvo mayor diversidad y equidad, además de que fue significativamente diferente a la parcela en monocultivo más alejada, pero no a la más cercana, la parcela en policultivo compartió la mayor similaridad de insectos con la parcela en monocultivo más cercana a este

Insights into the Molecular Basis of Huanglongbing Tolerance in Persian Lime (<i>Citrus latifolia</i> Tan.) through a Transcriptomic Approach

Huanglongbing (HLB) is a vascular disease of Citrus caused by three species of the α-proteobacteria “Candidatus Liberibacter”, with “Candidatus Liberibacter asiaticus” (CLas) being the most widespread and the one causing significant economic losses in citrus-producing regions worldwide. However, Persian lime (Citrus latifolia Tanaka) has shown tolerance to the disease. To understand the molecular mechanisms of this tolerance, transcriptomic analysis of HLB was performed using asymptomatic and symptomatic leaves. RNA-Seq analysis revealed 652 differentially expressed genes (DEGs) in response to CLas infection, of which 457 were upregulated and 195 were downregulated. KEGG analysis revealed that after CLas infection, some DEGs were present in the plant–pathogen interaction and in the starch and sucrose metabolism pathways. DEGs present in the plant–pathogen interaction pathway suggests that tolerance against HLB in Persian lime could be mediated, at least partly, by the ClRSP2 and ClHSP90 genes. Previous reports documented that RSP2 and HSP90 showed low expression in susceptible citrus genotypes. Regarding the starch and sucrose metabolism pathways, some genes were identified as being related to the imbalance of starch accumulation. On the other hand, eight biotic stress-related genes were selected for further RT-qPCR analysis to validate our results. RT-qPCR results confirmed that symptomatic HLB leaves had high relative expression levels of the ClPR1, ClNFP, ClDR27, and ClSRK genes, whereas the ClHSL1, ClRPP13, ClPDR1, and ClNAC genes were expressed at lower levels than those from HLB asymptomatic leaves. Taken together, the present transcriptomic analysis contributes to the understanding of the CLas-Persian lime interaction in its natural environment and may set the basis for developing strategies for the integrated management of this important Citrus disease through the identification of blanks for genetic improvement