Delayed Senescence and Marketability Index Preservation of Blackberry Fruit by Preharvest Application of Chitosan and Salicylic Acid.

Blackberry fruits are appreciated as a source of nutrients and compounds related to benefit human health. However, they are highly perishable and very susceptible to decay factors. Current methods to improve and maintain blackberry quality are limited in use because of the fruit's fragile physical properties. Regarding these properties, it has been reported that the activities of certain enzymes are linked to senescence and fruit softening processes. This study was aimed to assess the effect of salicylic acid (SA) and chitosan (COS) as preharvest treatments on the physiology related to improving fruit conservation and preserving the marketability index of blackberry fruit. The preharvest treatments were foliar sprayed on blackberry plants at different concentrations. The activities of enzymes superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and polygalacturonase (PG) were measured. Total soluble solids (TSS), titratable acidity (TA), TSS/TA ratio, and marketability index (MI) were analyzed after 144 h of storage. The application of 3 mM of SA and 0.25% of COS treatments preserved the MI of blackberries by reducing leakage, red drupelet reversion (RDR), and mycelium presence in the fruit. SA application increased SOD, CAT, and PAL activities. Our results also showed that SA and COS preharvest treatments modified the activity of the cell wall degrading enzyme PG, which might play a role in improving the shelf life and resistance to decay factors of blackberry fruit without any significant effects on physicochemical properties like TSS, TA, and the TSS/TA ratio.

A Novel Isolate of Bacillus cereus Promotes Growth in Tomato and Inhibits Clavibacter michiganensis Infection under Greenhouse Conditions.

The need to produce food in a sustainable way to counteract the effects of excessive use of agrochemicals opens the door to the generation of new technologies that are not based on fossil fuels and are less toxic to ecosystems. Plant growth-promoting bacteria (PGPB) could represent an alternative to chemical biofertilizers and pesticides offering protection for biotic and abiotic stresses. In this work, a bacterial isolate from roots of castor bean (Ricinus communis) was identified and named as Bacillus cereus strain "Amazcala" (B.c-A). This isolate displayed the ability to solubilize inorganic phosphate and produce gibberellic acid (GA3). Moreover, this bacterium provided significant increases in height, stem width, dry weight, and total chlorophyll content in tomato plants. Interestingly, B.c-A also significantly decreased the severity of bacterial canker disease on tomato caused by Clavibacter michiganensis (Cmm) in preventive disease assays under greenhouse conditions. Based on our results, B.c-A can be considered as PGPB and a useful tool in Cmm disease control on tomato plant under greenhouse conditions.

Plant Hormesis Management with Biostimulants of Biotic Origin in Agriculture.

Over time plants developed complex mechanisms in order to adapt themselves to the environment. Plant innate immunity is one of the most important mechanisms for the environmental adaptation. A myriad of secondary metabolites with nutraceutical features are produced by the plant immune system in order to get adaptation to new environments that provoke stress (stressors). Hormesis is a phenomenon by which a stressor (i.e., toxins, herbicides, etc.) stimulates the cellular stress response, including secondary metabolites production, in order to help organisms to establish adaptive responses. Hormetins of biotic origin (i.e., biostimulants or biological control compounds), in certain doses might enhance plant performance, however, in excessive doses they are commonly deleterious. Biostimulants or biological control compounds of biotic origin are called "elicitors" that have widely been studied as inducers of plant tolerance to biotic and abiotic stresses. The plant response toward elicitors is reminiscent of hormetic responses toward toxins in several organisms. Thus, controlled management of hormetic responses in plants using these types of compounds is expected to be an important tool to increase nutraceutical quality of plant food and trying to minimize negative effects on yields. The aim of this review is to analyze the potential for agriculture that the use of biostimulants and biological control compounds of biotic origin could have in the management of the plant hormesis. The use of homolog DNA as biostimulant or biological control compound in crop production is also discussed.

Silencing of a Germin-Like Protein Gene (CchGLP) in Geminivirus-Resistant Pepper (Capsicum chinense Jacq.) BG-3821 Increases Susceptibility to Single and Mixed Infections by Geminiviruses PHYVV and PepGMV.

Germin-like proteins (GLPs) are encoded by a family of genes found in all plants, and in terms of function, the GLPs are implicated in the response of plants to biotic and abiotic stresses. CchGLP is a gene encoding a GLP identified in a geminivirus-resistant Capsicum chinense Jacq accession named BG-3821, and it is important in geminivirus resistance when transferred to susceptible tobacco in transgenic experiments. To characterize the role of this GLP in geminivirus resistance in the original accession from which this gene was identified, this work aimed at demonstrating the possible role of CchGLP in resistance to geminiviruses in Capsicum chinense Jacq. BG-3821. Virus-induced gene silencing studies using a geminiviral vector based in PHYVV component A, displaying that silencing of CchGLP in accession BG-3821, increased susceptibility to geminivirus single and mixed infections. These results suggested that CchGLP is an important factor for geminivirus resistance in C. chinense BG-3821 accession.

Perspective for Aquaponic Systems: "Omic" Technologies for Microbial Community Analysis.

Aquaponics is the combined production of aquaculture and hydroponics, connected by a water recirculation system. In this productive system, the microbial community is responsible for carrying out the nutrient dynamics between the components. The nutrimental transformations mainly consist in the transformation of chemical species from toxic compounds into available nutrients. In this particular field, the microbial research, the "Omic" technologies will allow a broader scope of studies about a current microbial profile inside aquaponics community, even in those species that currently are unculturable. This approach can also be useful to understand complex interactions of living components in the system. Until now, the analog studies were made to set up the microbial characterization on recirculation aquaculture systems (RAS). However, microbial community composition of aquaponics is still unknown. "Omic" technologies like metagenomic can help to reveal taxonomic diversity. The perspectives are also to begin the first attempts to sketch the functional diversity inside aquaponic systems and its ecological relationships. The knowledge of the emergent properties inside the microbial community, as well as the understanding of the biosynthesis pathways, can derive in future biotechnological applications. Thus, the aim of this review is to show potential applications of current "Omic" tools to characterize the microbial community in aquaponic systems.

Ecophysiological responses to the effect of annual management on an endemic viviparous fish in central plateau of México

Studies on the biological aspects of fish typically focus on species that currently have commercial value, causing species that lack such market value to be ignored. This is the case of several freshwater fish, specifically of several members of the Goodeidae family. In the State of Querétaro there are several species of this family characterized for being viviparous and having distinctive sexual dimorphism that may have commercial potential. The subject of this study is Girardinichthys multiradiatus, a viviparous fish endemic to the upper-half of the Lerma River basin. The lack of knowledge regarding its biology and ecology has prevented the development of guidelines to manage its habitat and to preserve its population. The objective was to determine the ecophysiological responses of G. multiradiatus to its environmental management. From the sampling (24 hours every two months) population structure and dynamics were analyzed throughout a hydrological cycle using meristic data (standard length). Trophic and ecophysiological responses to fluctuations in environmental factors were also identified. Although the mexcalpique is a polytrophic species, results show that it prefers feeding on Diptera or Cladocera, while detritus is the third substance frequently found in their stomachs. Environmentally, the water regime is responsible for fluctuations in the population dynamics of the species, while temperature changes are the most influence its energy balance. These results can guide efforts to conserve this species and its habitat.

Los estudios sobre aspectos biológicos de los peces se centran, generalmente, en especies que actualmente tienen interés comercial, lo que ocasiona que las especies que carecen de tal valor en el mercado estén prácticamente olvidadas; tal es el caso de varios peces de agua dulce y más específicamente de algunos integrantes de la familia Godeidae. En el estado de Querétaro se encuentran varias especies pertenecientes a esta familia que se caracterizan por ser vivíparas y presentar un marcado dimorfismo sexual, aspectos que pudieran definir un potencial comercial. El pez objeto de este estudio es Girardinichthys multiradiatus, especie endémica de la parte alta-media de la cuenca del río Lerma; los lugares donde habita presentan procesos de degradación, fragmentación del hábitat y extracción de agua, que ponen en riesgo su existencia. Además, la falta de conocimiento sobre su biología y ecología, no permiten que se elaboren pautas de gestión de sus poblaciones o hábitats con fines de conservación y preservación de la especie o de los procesos ecológicos que mantienen la estabilidad del ecosistema que ocupa. En el presente trabajo se estudió la población de G. multiradiatus localizada en el bordo de San Martín, Amealco. El objetivo del presente trabajo fue determinar las respuestas ecofisológicas de G. multiradiatus debido al manejo de su ambiente. Se hicieron ciclos de 24 horas en muestreos bimensuales a lo largo de un ciclo hidrológico en el que se analizaron la estructura y dinámica de la población; asimismo, se determinaron las respuestas tróficas y ecofisiológicas de la población ante las fluctuaciones de los factores ambientales de su entorno. Los resultados muestran que aunque el mexcalpique es polítrofo, prefiere dípteros, cladóceros y detritus, habiendo diferencias alimentarias entre las clases de edades. G. multiradiatus presenta 12 clases de talla que van de 8 a 48 mm de longitud patrón. En el medio ambiente, el régimen de agua es responsable de las fluctuaciones en la dinámica poblacional de las especies, mientras que el cambio de temperatura es el factor de mayor influencia sobre su balance energético. Estos resultados pueden guiar los esfuerzos para conservar esta especie y su hábitat.

A germin-like protein gene (CchGLP) of Capsicum chinense Jacq. is induced during incompatible interactions and displays Mn-superoxide dismutase activity.

A germin-like gene (CchGLP) cloned from geminivirus-resistant pepper (Capsicum chinense Jacq. Line BG-3821) was characterized and the enzymatic activity of the expressed protein analyzed. The predicted protein consists of 203 amino acids, similar to other germin-like proteins. A highly conserved cupin domain and typical germin boxes, one of them containing three histidines and one glutamate, are also present in CchGLP. A signal peptide was predicted in the first 18 N-terminal amino acids, as well as one putative N-glycosylation site from residues 44-47. CchGLP was expressed in E. coli and the recombinant protein displayed manganese superoxide dismutase (Mn-SOD) activity. Molecular analysis showed that CchGLP is present in one copy in the C. chinense Jacq. genome and was induced in plants by ethylene (Et) and salicylic acid (SA) but not jasmonic acid (JA) applications in the absence of pathogens. Meanwhile, incompatible interactions with either Pepper golden mosaic virus (PepGMV) or Pepper huasteco yellow vein virus (PHYVV) caused local and systemic CchGLP induction in these geminivirus-resistant plants, but not in a susceptible accession. Compatible interactions with PHYVV, PepGMV and oomycete Phytophthora capsici did not induce CchGLP expression. Thus, these results indicate that CchGLP encodes a Mn-SOD, which is induced in the C. chinense geminivirus-resistant line BG-3821, likely using SA and Et signaling pathways during incompatible interactions with geminiviruses PepGMV and PHYVV.