Search

The objective of this work was to obtain high‐yielding F1 hybrids of the habanero pepper, using 10 outstanding parents in a line‐tester genetic design. General combinatorial ability and specific combinatorial ability were evaluated in the parents' and the hybrids F1 obtained, respectively. Heterosis was determined in the 18 hybrids obtained. The technique of HPLC was used to evaluate the capsaicin content in the fruit of 10 parents and 18 hybrids of habanero pepper. The DNA profiles were analysed as part of the characterization of the germplasm of the species conserved at the CICY. Furthermore, the molecular variation of the genotypes under investigation was assessed using eight SSR and nine ISSR markers. The results showed the presence of substantial morphoagronomic and molecular variability among the habanero pepper genotypes evaluated. Genetic similarities of 83%–93% between parents and 76%–94% between hybrids were found. The most productive hybrids were H8, H10 and H19 with 3.13 to 4.29 kg/plant, respectively, these came from crosses where RNJ‐04 (P26) as the male parent and the hybrid H60 (4.92 kg/plant) that comes from the male parent RES‐08 (P30). Likewise, the H7 hybrid had the highest capsaicin content (128.41 mg/g dry weight, 960,687.00 SHU). Hybrids H43 with 114.39 mg/g DW and 90,444.30 SHU, and H51 with 11.61 mg/g DW and 934,745.07 SHU respectively, also stood out. [ABSTRACT FROM AUTHOR]

Oil palm (Elaeis guineensis Jacq.) has become the largest source of vegetable oil in the world. It is known that all existing genotypes of this species are related, so their genetic variability is considered to be low. In Mexico, all oil palm plantations are located in the southeast of the country, and they are established with different origins seeds, which has caused poor yields and resulted in the need to establish a genetic improvement program. Therefore, in this study, the extent of genetic diversity among 151 oil palm accessions from all producing regions of Mexico was assessed with twenty simple sequence repeats (SSRs) and seven random amplified microsatellite (RAM) markers. The markers utilized proved to be useful in revealing high existing genetic variability, with a total of 1218 and 708 alleles detected and polymorphic information content (PIC) of 0.96 and 0.91 for RAM and SSR, respectively. The genetic distance among all accessions of oil palm collected ranged between 31% and 82% for similarity. Accessions from Tabasco and Veracruz presented the greatest and smallest genetic diversity, respectively. These results can allow breeding strategies to be established for the genetic improvement of this crop in Mexico. [ABSTRACT FROM AUTHOR]

Selection of lines from segregating generations and breeding hybrids to exploit heterosis or heterobeltiosis is an effective tool for improving economically important traits in the genus Capsicum. The objective of this study was to identify high potential parents to obtain high-yielding F1 hybrids using a Line × Tester (8 × 2) mating design in the Habanero pepper improvement programme. Ten parents and 16 hybrids were evaluated in order to determine their values of general combining ability, specific combining ability, heterosis, and heterobeltiosis. Parent NKA-11 had the highest values of GCA for different quantitative variables of the fruit, which does it suitable for future improvement works, and tester RNJ-04 showed the highest value of GCA for fruit length. The quantitative variables evaluated confirm a significant genetic variability among the Habanero pepper genotypes studied. The best hybrids were NEK-03xRNJ-04, NBA-06xRNJ-04, AKN-07xRNJ-04, and RKI-10xRNJ-04, which showed their high productive potential with values between 3.13 and 4.92 Kg/Pta, a quality, that would open to them the national market for fresh consumption. Based on the GCA values of the parents and heterosis of the progenies, it is concluded hybridization would be the most appropriate genetic improvement method to increase both yield (YP) and the number of fruits for plant. [ABSTRACT FROM AUTHOR]

Active metabolites from plants are considered safer than synthetic chemicals for the control of plant-parasitic nematodes of the genus Meloidogyne. In the present work, 75 aqueous extracts (AEs) from different vegetative parts of 34 native plant species of the Yucatan Peninsula were evaluated against second-stage juveniles (J2s) of Meloidogyne incognita and M. javanica in microdilution assays. The highest mortality (M) against both Meloidogyne species was produced by the foliar AE from Alseis yucatanensis (M ≥ 94%) and Helicteres baruensis (M ≥ 77%) at 3% w/v after 72 h. Other active AEs at 3% were from the leaves of Croton itzaeus and stems of H. baruensis (M: 87–90%) on M. javanica and the stems of Annona primigenia and the leaves of Morella cerifera on M. incognita (M: 92–97%). The AEs from A. yucatanensis had the lowest LD50 against M. incognita (0.36% w/v), and against M. javanica (3.80% w/v). In an acute ecotoxicity assay of the most promising AEs using non-target earthworms (Eisenia fetida), the AE of A. yucatanensis had slight acute toxicity (LD50: 2.80% w/v), and the rest of the most active AEs were not ecotoxic. These tropical plants are potential candidates for further studies as biorational agents for controlling Meloidogyne species. [ABSTRACT FROM AUTHOR]

Kretzschmaria zonata (Lév.) P.M.D. Martin is a fungus that causes root and neck rot in teak (Tectona grandis L.) worldwide. The detection of this fungus in asymptomatic plants is essential for its control but, to date, the disease can only be detected morphologically or by sequencing this fungus's isolates. The aim of this work was to design, at least, one set of specific PCR primers for a quickly, early and accurate diagnosis of this pathogen. Nineteen isolates of K. zonata from teak plants at different locations in Mexico were obtained. ITS region sequences and two software were used to design the PCR-based primers. All primers obtained were tested on DNA samples from infected teak tissue, K. zonata pure isolates, and other different fungi species (in vitro and in silico). The sensitivity of the primers was evaluated at five different concentrations of target DNA. The primer set KZ-AQ-3F/KZ-AQ-3R was selected for its specificity (amplifies only K. zonata) and sensitivity (1 × 10−5 ng/µL detection). This is the first report of a Kretzschmaria zonata-specific primer set. Tests carried out on asymptomatic teak and artificially inoculated plants with this fungus demonstrated the usefulness of these primers for the accurate detection of K. zonata, and taking early control measures. [ABSTRACT FROM AUTHOR]

The objective of this study was to establish an efficient—direct or indirect—regeneration system for pineapple (Ananas comosus L.) plants, with a high rate of multiplication and that would preserve the genetic identity of the donor genotype (Hybrid 'MD2') in the regenerated plants. Ten treatments, with different concentrations of 2,4-Dichlorophenoxyacetic (2,4-D) and Picloram (P), in the absence or presence of 6-Benzylaminopurine (BAP), were used for in vitro morphogenesis induction, as well as histological and molecular techniques, in order to characterize the morphogenic responses induced. Significant differences between treatments tested, to induce callus and buds, were assessed by the Kruskal Wallis method and the Mann–Whitney U-tests. Different pineapple regeneration routes were identified, showing the high regeneration potential of this species. The medium containing 2 mg L−1 2,4-D and 2 mg L−1 BAP, where indirect somatic embryogenesis occurred, was selected as the most efficient treatment, with an average of 120 somatic embryos per explant, differing significantly from the rest of the treatments. It was also demonstrated that the pineapple plants regenerated in vitro preserved the genetic identity of the donor genotype, which represents a high degree of confidence for the application of indirect somatic embryogenesis for A. comusus clonal propagation. [ABSTRACT FROM AUTHOR]

In this study, three commercial botanical acaricides (BA) were evaluated on two species of phytophagous mites, the red palm mite (Raiella indica) and the papaya mite (Oligonychus sp.). The toxicity of the BA on the predatory mites Neoseiulus californicus and Phytoseiulus persimilis was also assessed. For R. indica, CinnAcar and EPA-90 caused more than 90% decrease in the population density in the laboratory. In field trial, CinnAcar was the most effective in suppressing the mite population density. For Oligonychus sp., CinnAcar and EPA-90 caused up to 88.5 and 95.2% mortality in the laboratory. In greenhouse trial, EPA-90 caused more than 90% decrease in the population density of motile stages. Residual exposure showed that EPA-90 had moderate toxicity to the phytoseiid predators, causing 48% mortality in N. californicus and 55% mortality in P. persimilis, whereas CinnAcar and NeemAcar produced 22 to 32% mortality. [ABSTRACT FROM AUTHOR]

Presence of alternate hosts of plants is a great threat to the agriculture industry. Plants from several species growing in the papaya orchards affected by papaya sticky disease were examined for Papaya meleira virus (PMeV) infection causing this disease. The viral dsRNA was already detected in some plants from the family Poaceae or in watermelon. To identify new hosts of PMeV, we have collected 38 plant species belonging to 15 families of common weed species found in papaya-growing areas in México and used reverse-transcription PCR (RT-PCR) or quantitative real-time RT-PCR (RT-qPCR) for virus detection. We have detected the viral RNA in 11 species belonging to the families Acanthaceae, Fabaceae and Poaceae. Under experimental conditions, PMeV-Mx in Panicum hirsutum and Ruellia nudiflora inoculated weed species, showed that PMeV-Mx is able to replicate in plant cells of these species and spread in a systemic way. These results highlight the importance of weed species as potential virus reservoirs for PMeV-Mx. [ABSTRACT FROM AUTHOR]

Looking for a biotechnical potential, aqueous extracts of leaves of 12 native species used in the Mayan traditional medicine of the coastal dune and mangrove of Yucatan (Mexico) were selected to evaluate their biological activities. Rhizophora mangle and Manilkara zapota showed the highest free radical scavenging activity (3.94 ± 0.19 and 6.42 ± 0.32 μg/mL, respectively), and the highest antihypertensive activity was obtained from Solanum donianum (0.38 μg/mL). The anti-hyperglycemic activity of these species was also tested; the highest activities were registered with R. mangle. The antimicrobial activity of Malvaviscus arboreus, S. donianum, M. zapota, and R. mangle at 10% (w/v) was positive against six human pathogenic bacteria and Bonellia macrocarpa against one pathogenic fungus. Solanum donianum, M. zapota, B. macrocarpa, and R. mangle were positive against two pathogenic plant fungi. These results show that the aqueous extracts of five native plants of the Yucatan coast have potential as antioxidants, ACE inhibitors, α-amylase and α-glucosidase inhibitors, and as antimicrobials, which make their exploration for utilization in the agricultural and pharmaceutical industries a possibility. [ABSTRACT FROM AUTHOR]

The macroalgae consortium biomass in the Mexican Caribbean represents an emerging and promising biofuel feedstock. Its biological pretreatment and potential for energetic conversion to biomethane were investigated, since some macroalgae have hard cell walls that present an obstacle to efficient methane production when those substrates are used. It has been revealed by anaerobic digestion assays that pretreatment with a Bm-2 strain (Trametes hirsuta) isolated from decaying wood in Yucatan, Mexico was 104 L CH4•kg VS-1; In fact, the fungal pretreatment produced a 20% increase in methane yield, with important amounts of alkali metals Ca, K, Mg, Na of 78 g/L, ash 35.5% and lignin 15.6%. It is unlikely that high concentrations of ash and alkali metals will produce an ideal feedstock for combustion or pyrolysis, but they can be recommended for a biological process. [ABSTRACT FROM AUTHOR]

Ramon (Brosimum alicastrum) is a forest tree native to the Mesoamerican region and the Caribbean. The flour obtained from Ramon seeds is 75% carbohydrate, of which 63% is starch, indicating its potential as a novel raw material for bioethanol production. The objective of this study was to produce ethanol from Ramon flour using a 90 °C thermic treatment for 30 min and a native yeast strain (Candida tropicalis) for the fermentation process. In addition, the structure of the flour and the effects of pretreatment were observed via scanning electron microscopy. The native yeast strain was superior to the commercial strain, fermenting 98.8% of the reducing sugar (RS) at 48 h and generating 31% more ethanol than commercial yeast. One ton of flour yielded 213 L of ethanol. These results suggest that Ramon flour is an excellent candidate for ethanol production. This is the first report on bioethanol production using the starch from Ramon seed flour and a native yeast strain isolated from this feedstock. This alternative material for bioethanol production minimizes the competition between food and energy production, a priority for Mexico that has led to significant changes in public policies to enhance the development of renewable energies. [ABSTRACT FROM AUTHOR]

Sticky disease, which is caused by Papaya meleira virus (PMeV), is a significant papaya disease in Brazil and Mexico, where it has caused severe economic losses, and it seems to have spread to Central and South America. Studies assessing the pathogen-host interaction at the nano-histological level are needed to better understand the mechanisms that underlie natural resistance. In this study, the topography and mechanical properties of the leaf midribs and latex of healthy and PMeV-infected papaya plants were observed by atomic force microscopy and scanning electron microscopy. Healthy plants displayed a smooth surface with practically no roughness of the leaf midribs and the latex and a higher adhesion force than infected plants. PMeV promotes changes in the leaf midribs and latex, making them more fragile and susceptible to breakage. These changes, which are associated with increased water uptake and internal pressure in laticifers, causes cell disruption that leads to spontaneous exudation of the latex and facilitates the spread of PMeV to other laticifers. These results provide new insights into the papaya-PMeV interaction that could be helpful for controlling papaya sticky disease. [ABSTRACT FROM AUTHOR]

When this article was originally published in Plant Genetic Resources, it contained an error in the labelling of who was the first author. Combining Ability, Heterosis, and Heterobeltiosis to Select Highly Productive F1 Hybrids of Habanero Pepper (Capsicum chinense Jacq.) Combining ability, heterosis, and heterobeltiosis to select highly productive F1 hybrids of habanero pepper (Capsicum chinense Jacq.). [Extracted from the article]

Vinasse is the dark-colored wastewater that is generated by bioethanol distilleries from feedstock molasses. The vinasse that is generated from molasses contains high amounts of pollutants, including phenolic compounds and melanoindin. The goal of this work was to study the expression of laccase genes in the Trametes hirsuta strain Bm-2, isolated in Yucatan, Mexico, in the presence of phenolic compounds, as well as its effectiveness in removing colorants from vinasse. In the presence of all phenolic compounds tested (guaiacol, ferulic acid, and vanillic acid), increased levels of laccase-encoding mRNA were observed. Transcript levels in the presence of guaiacol were 40 times higher than those in the control. The lcc1 and lcc2 genes of T. hirsuta were differentially expressed; guaiacol and vanillin induced the expression of both genes, whereas ferulic acid only induced the expression of lcc2. The discoloration of vinasse was concomitant with the increase in laccase activity. The highest value of enzyme activity (2543.7 U/mL) was obtained in 10% (v/v) vinasse, which corresponded to a 69.2% increase in discoloration. This study demonstrates the potential of the Bm-2 strain of T. hirsuta for the biodegradation of vinasse. [ABSTRACT FROM AUTHOR]

Papaya meleira virus (PMeV) is the causal agent of papaya sticky disease, which is characterized by a spontaneous exudation of fluid and aqueous latex from the papaya fruit and leaves. The latex oxidizes after atmospheric exposure, resulting in a sticky feature on the fruit from which the name of the disease originates. PMeV is an isometric virus particle with a double-stranded RNA (dsRNA) genome of approximately 12 Kb. Unusual for a plant virus, PMeV particles are localized on and linked to the polymers present in the latex. The ability of the PMeV to inhabit such a hostile environment demonstrates an intriguing interaction of the virus with the papaya. A hypersensitivity response is triggered against PMeV infection, and there is a reduction in the proteolytic activity of papaya latex during sticky disease. In papaya leaf tissues, stress responsive proteins, mostly calreticulin and proteasome-related proteins, are up regulated and proteins related to metabolism are down-regulated. Additionally, PMeV modifies the transcription of several miRNAs involved in the modulation of genes related to the ubiquitin-proteasome system. Until now, no PMeV resistant papaya genotype has been identified and roguing is the only viral control strategy available. However, a single inoculation of papaya plants with PMeV dsRNA delayed the progress of viral infection. [ABSTRACT FROM AUTHOR]

Papaya meleira virus (PMeV) causes sticky disease in Carica papaya in Brazil and Mexico. Despite its economic importance and the need for effective phytosanitary control, it remains unknown whether any insect is the vector of this virus. The aim of this work was to identify potential insect vectors of the PMeV-Mexican variant (PMeV-Mx) and determine whether these potential vectors are capable of transmitting the virus. Adult insects were collected in papaya fields in the south-southeast region of Mexico and were identified morphologically and molecularly. Their abundance and frequency were determined, and quantitative reverse transcription polymerase chain reaction was performed to establish if they carried PMeV-Mx. The Cicadellidae family (Hemiptera) was the most diverse and abundant, and Empoasca papayae was the most abundant species and had the highest virus titers. PMeV-Mx transmission assays were conducted under controlled conditions using E. papayae on C. papaya 'Maradol'. E. papayae was a carrier of PMeV-Mx at 6 h after exposure, and its viral titer increased with time, peaking at 2.125 pg/μl of PMeV-Mx RNA from 20 ng/µl of cDNA, 5 days after exposure (dae). From 14 days after plants were exposed to insects, PMeV-Mx was detected and quantified in 100% of the evaluated papaya plants, whose viral RNA titer increased from 0.06 (21 dae) to 26.6 pg/μl of PMeV-Mx RNA (60 dae) from 20 ng/µl of cDNA. Three months later, these plants developed sticky disease symptoms, demonstrating that E. papayae is capable of transmitting PMeV-Mx to C. papaya 'Maradol'.

An aluminium (Al)-tolerant cell line (LAMt) of coffee (Coffea arabica L.) was obtained from a cell suspension culture and biochemically and molecularly characterized in an MS medium at half ionic strength and low pH. LAMt grew 30% more than the control line (susceptible to Al) in the presence of different concentrations of Al, showed a lower free Al concentration in the medium and had higher phospholipase C specific activity (80%). Membrane integrity of the LAMt was 50% greater than the control line when both were incubated in the presence of different Al concentrations (measured by Evans Blue uptake). Finally, the use of microsatellite primers revealed no difference in the DNA pattern of both cell lines.