THE TOMATO BROWN RUGOSE FRUIT VIRUS IS RESTRICTED TO SPECIFIC AREAS IN SONORA, MEXICO - A STUDY OF 2021-2022 SEASON

Background: Tomato brown rugose fruit virus (ToBRFV) has spread worldwide affecting tomato crop production in several countries. Although there are commercial ToBRFV-resistant tomato varieties; still, careful monitoring of its prevalence is necessary for establishing feasible epidemiological control programs. Since Sonora has a strategic geographic location for tomato cultivation and export, studies on the detection and prevention of ToBRFV outbreaks are pertinent as part of the actions to achieve the eradication of this virus. Objective: To determine the recent prevalence of ToBRFV in tomato-producing areas of the state of Sonora, Mexico in the period 2021-2022, using a combination of molecular and serological tools. Methodology: Samples of tomato leaves and fruits were collected from commercial greenhouses in different regions of Sonora from September 2021 to June 2022. Forty-four tomato leaves and 42 seed samples were analyzed for ToBRFV using reverse transcriptase-polymerase chain reaction and by direct detection of viral epitopes by immunochromatography. Results: 60% and 48% of the samples tested positive for ToBRFV by immunochromatography and RT-qPCR, respectively, showing an exact agreement regarding the samples’ origin. Implications: Future research may focus on genomic analysis of viral isolates that would provide clues of ToBRFV propagation speed and emergence of particular viral strains typical of the place of origin. Conclusion: The presence of ToBRFV in the state of Sonora, Mexico is limited to specific geographic sites, which suggests that local regulations and phytosanitary actions have worked to control the spread of the virus

Pectic and Galacturonic Acid Oligosaccharides on the Postharvest Performance of Citrus Fruits

Orange [Citrus sinensis (L.) Osbeck] and grapefruit (Citrus paradisi Macfad) citrus fruits are prone to develop different peel physiological disorders caused by storage at both chilling and nonchilling temperatures. The effect of galacturonic acid oligosaccharides (GAOs) and pectic oligosaccharides (POs) in reducing postharvest nonchilling peel pitting (NCPP), decay, and chilling injury (CI) in orange cv. Navelina and the effect of POs in reducing CI in grapefruit cv. Rio Red, were investigated. The incidence of these disorders was examined in fruits stored at chilling and nonchilling temperatures and at 90% to 95% relative humidity (RH). POs showed a better efficacy than GAOs in reducing postharvest losses in orange. The POs were able to reduce NCPP and decay in ‘Navelina’ fruits stored at 20 °C, irrespective of the fruit maturity stage. The application of 10 g·L−1 POs also reduced CI and the chilling-induced ethylene production in oranges and grapefruits maintained at the chilling temperature. Likewise, the decrease in ethylene production found in ‘Navelina’ fruits that developed NCPP during storage at the nonchilling temperature was related to lower peel damage. Moreover, results showed that POs do not induce an increase in ethylene when fruit are stored under conditions that do not cause stress-related injury to fruit. Therefore, POs efficacy in reducing postharvest physiological disorders is not likely mediated by ethylene. Overall results indicate that the application of POs may be an acceptable alternative to mitigate postharvest losses of citrus fruits.Araceli M. Vera-Guzman is a doctoral student in the graduate program of CIAD, and received a graduate fellowship from CONACyT, México. Part of this work was supported by the Spanish Ministry of Science and Technology (Research Grant AGL2013-41734-R and AGL2014-55802-R) and by the Generalitat Valenciana, Spain (Grant PROMETEOII/2014/027).Peer reviewe

Total RNA quality of lyophilized and cryopreserved dormant grapevine buds

Background: Plant tissues must be preserved in their collection state, especially for genome-wide expression profile studies. Lyophilization is a feasible, affordable tool when fresh tissues cannot be shipped at ultralow temperatures from their origin to the place of analysis. In this study, the total RNA quality of dormant grapevine buds (Vitis vinifera L. cv. ‘Flame Seedless’) of freeze-dried samples stored at room temperature conditions was evaluated and compared to that of cryopreserved (-80°C) grapevine buds. Results: Good yield and quality of RNA were obtained from freeze-dried dormant buds stored at room temperature for 0, 3 and 6 weeks after they were lyophilized. Further experiments confirmed that the extracted total RNA could be used for actin and β-tubulin PCR gene amplification. Conclusion: High-quality RNA that is useful for downstream applications was obtained from freeze-dried dormant grapevine bud tissue, similarly to the RNA obtained from cryopreserved dormant grapevine buds

Chitosan Sensitivity of Fungi Isolated from Mango (Mangifera indica L.) with Anthracnose

In Mexico, the mango crop is affected by anthracnose caused by Colletotrichum species. In the search for environmentally friendly fungicides, chitosan has shown antifungal activity. Therefore, fungal isolates were obtained from plant tissue with anthracnose symptoms from the state of Guerrero in Mexico and identified with the ITS and β-Tub2 genetic markers. Isolates of the Colletotrichum gloeosporioides complex were again identified with the markers ITS, Act, β-Tub2, GADPH, CHS-1, CaM, and ApMat. Commercial chitosan (Aldrich, lot # STBF3282V) was characterized, and its antifungal activity was evaluated on the radial growth of the fungal isolates. The isolated anthracnose-causing species were C. chrysophilum, C. fructicola, C. siamense, and C. musae. Other fungi found were Alternaria sp., Alternaria tenuissima, Fusarium sp., Pestalotiopsis sp., Curvularia lunata, Diaporthe pseudomangiferae, and Epicoccum nigrum. Chitosan showed 78% deacetylation degree and a molecular weight of 32 kDa. Most of the Colletotrichum species and the other identified fungi were susceptible to 1 g L−1 chitosan. However, two C. fructicola isolates were less susceptible to chitosan. Although chitosan has antifungal activity, the interactions between species of the Colletotrichum gloeosporioides complex and their effect on chitosan susceptibility should be studied based on genomic changes with molecular evidence

Byrsonima crassifolia L. Kunth a bio-resource with potential: Overview and opportunities

Byrsonima crassifolia L. Kunth is a plant native to the Americas that grows in tropical and subtropical areas. Fresh B. crassifolia fruits are a good source of ascorbic acid and carotenoids and contain volatile compounds such as butyric and caproic acids. Although B. crassifolia is commonly exploited from wild natural ecosystems, it exhibits the potential to become a crop plant. When optimal agronomic management systems support propagation by seed, fruits with more homogeneous characteristics can be produced compared to those obtained from wild or backyard plants. B. crassifolia fruits can be found in local markets in Central and South America. The pulp, peel, and other B. crassifolia fruit components can be processed to make traditional and innovative food products, namely candies, cookies, cakes, candied fruits, ice creams, sorbets, jellies, juices, liqueurs, jams, nectars, pickles, and fruit drinks as an alternative to avoid the waste of overripe fruits. Additionally, the woody fraction of the B. crassifolia tree is used as a source of firewood, as shade, and for constructing living fences. These uses also allow the maximum use of biomass by establishing support for cultivation with the circular economy and strengthening food security. Therefore, this review aims to provide insights into the generation and dissemination of knowledge supporting the development of strategies in the areas of agronomy, postharvest management, and technological processing of B. crassifolia to promote its sustainable use and exploitation

Antagonistic Activity of Bacteriocin-like Inhibitory Substances from <i>Enterococcus lactis</i> Isolated from the Surface of Jalapeno Pepper against Foodborne Pathogens

Lactic acid bacteria (LAB) can produce peptides known as bacteriocins with antagonistic activity against foodborne pathogens. The potential of LAB isolated from the surface of jalapeno peppers to produce bacteriocins with antagonistic activity against Listeria monocytogenes, Staphylococcus aureus, Escherichia coli O157:H7, and Salmonella Typhimurium was evaluated. Previously isolated LAB strains were reactivated, and their cell-free supernatants (CFSs) were evaluated. Out of 390 reactivated strains, 60 produced bacteriocin-like inhibitory substances (BLIS) since their antagonistic activity was lost after proteases addition. Subsequently, 16 BLIS showed heat resistance (HR-BLIS), retaining their bioactivity after heat treatment (121 °C for 15 min). By 16S rRNA gene sequencing and antibiotic susceptibility tests, LAB strains producing HR-BLIS were identified as Enterococcus lactis. Four HR-BLIS exhibited a minimum inhibitory concentration (MIC) of 80 mg/mL against L. monocytogenes. MIC and minimum bactericidal concentration (MBC) of HR-BLIS-67 for S. aureus (MIC = 80 mg/mL; MBC = 320 mg/mL), S. Typhimurium (MIC = 150 mg/mL; MBC = 250 mg/mL), and E. coli O157:H7 (MIC = 250 mg/mL; MBC = 400 mg/mL) were determined. LAB isolated from the surface of jalapeno pepper produced HR-BLIS (possibly enterocin) that exhibited broad-spectrum antagonistic activity against foodborne pathogens; therefore, they are a promising source of natural antimicrobials to ensure food safety