Cultivated tomato (Solanum lycopersicum L.) has undergone a reduction in its genetic base as a result of the processes of modern domestication and breeding, which has been extensively documented by molecular markers in different genotypes, both nationally and internationally. Faced with this situation, some plant breeders in Mexico have proposed making use of native Mexican germplasm, as well as of the genetic variation present in wild species related to the cultivated tomato. The aim of this study was to characterize agronomically, under greenhouse conditions, accessions of five wild relatives of the cultivated tomato for their incorporation into breeding programs of this vegetable. In addition, it is expected to reduce its vulnerability to climate change and adverse biotic and abiotic factors. The species described were Solanum pennellii L., Solanum pimpinellifollium L., Solanum peruvianum L., Solanum chilense R. and Solanum habrochaites S. The accessions were evaluated under greenhouse conditions under a completely randomized experimental design with four replications. Twelve traits of agronomic interest were evaluated to describe the variation between the accessions of each one of the evaluated species, which were studied by analysis of variance and comparison of means. The results showed high significance among the accessions of each one of the evaluated species for all the traits. The above shows that there is a high potential in each of the accessions of the species studied to exploit them genetically in the improvement of the cultivated tomato.

Milax gagates is one of the main pests in the cultivation of lettuce, causing considerable economic losses. Control with molluscicides totally or partially eliminates the pest but generates a negative impact on the environment due to their high toxicity. Biological management also allows controlling the pest, but in a specific and safe way for the environment. Therefore, the objective of this work was to evaluate the toxic effect of Bacillus thuringiensis, with Cry1 genes, against M. gagates by means of a bioassay. Seventy-five soil samples were taken from several municipalities in Norte de Santander, Colombia, from where 58 isolated colonies of B. thuringiensis with similar characteristics were obtained. Of these colonies, five showed the presence of Cry1 genes, and were those used in the bioassays together with the control B. thuringiensis var. Kurstaki. The treatments caused 90-100 % lethality to M. gagates at a concentration of 500 μg∙mL-1. The calculated LD99 suggests the use of 820 μg∙mL^-1 of the biopreparate to obtain 100 % lethality with any of the five isolates studied.

The consumption of nutraceutical foods, such as extracts of roselle (Hibiscus sabdariffa L.) calyces, improve health and prevent several diseases, attributable in part to the activity of their anthocyanins. Exposure of plants to high concentrations of some heavy metals stimulates the synthesis of anthocyanins; therefore, the objective of this study was to determine the effect of foliar application of Zn and Cu at high concentrations on calyx yield, anthocyanin content and physicochemical characteristics in three roselle genotypes. The Criolla Guerrero, Criolla Michoacán and Reina Roja genotypes were sown under rainfed conditions. The foliage of the plants in vegetative stage was sprayed with Zn and Cu solutions separately, making in total four applications of 300 mg∙L^-1. Both elements reduced the calyx yield in Criolla Guerrero, did not modify it in Criolla Michoacán and in Reina Roja the Zn increased the yield by 15.9 %, achieving 1,232 kg∙ha^-1. In all genotypes, the applications of these elements improved the content of anthocyanins and titratable acidity and decreased the content of ascorbic acid. Criolla Michoacán had the highest increase in anthocyanins, with 187 % Cu and with 175 % Zn; however, this genotype did not exceed the final anthocyanin content in Reina Roja, which with Cu recorded 22.68 mg∙g^-1. Therefore, the application of these elements is an alternative to increase the content of anthocyanins, to which some nutraceutical qualities are attributed.

The bacteria Clavibacter michiganensis subsp. michiganensis (Cmm) and Xanthomonas vesicatoria (Xv) are of great interest in tomato production because they cause major economic losses worldwide. They are transmitted by seeds and the management strategies for these pathogens in tomato production systems are not completely effective. Therefore, the objective of this research was to identify fluorescent Pseudomonas strains of different ecological origin and evaluate their antagonism against Cmm and Xv and their effect as growth promoters on tomato seed germination and seedling vigor. We evaluated 356 fluorescent Pseudomonas strains isolated from different ecological niches: roselle (Hibiscus sabdariffa L.) rhizosphere, tomato (Solanum lycopersicum L.) rhizosphere and Claviceps gigantean sclerotium mycosphere. Antagonism against C. michiganensis and Xanthomonas vesicatoria was evaluated in in vitro dual confrontation tests in King’s B culture medium, which generated 20 fluorescent P. strains antagonistic to one or both bacteria. The antagonistic strains (n = 20) were characterized metabolically by their production of 3-indole acetic acid (IAA) and siderophores (SID), and were identified genetically by the polymerase chain reaction (PCR) technique with the amplification and sequencing of the 16S rRNA gene by primers FD1 and RD1. The results of the metabolic characterization of the strains indicated that 65 % produced IAA and 100 % SID. Inoculation of these bacteria, by the Bio-priming technique, in tomato var. Rio Grande seeds showed that 95 % of them significantly (P ≤ 0.05) increased the germination rate (T50) and the dry biomass production of the seedling roots. The partial sequencing of the 16S rRNA gene identified the bacterial strains as Pseudomonas sp. (65 %), P. putida (25 %) and P. fluorescens (10 %).

The avocado belongs to the genus Persea, which is one of the most controversial genera of the Lauraceae family, since the relationships within the subgenus Persea are not clear and only recognized two species, Persea americana and Persea schiedeana. Its relationship with the subgenus Eriodaphne is also complex and there is a debate as to whether it is an independent genus. For this reason, the study aims to analyze the phylogenetic relationships within the genus Persea, with an emphasis on the subgenus Persea, using maximum parsimony and bayesian inference with the sequence of eight different fragments from nuclear, chloroplast and mitochondrial DNA. Sequences of the chloroplast ndhF, rbcL, matK, rpoC, trnH-psbA; mitochondria atp4 and cox3 and nuclear 18S rRNA were used. Fourteen fixed mutations were found in species of the subgenus Eriodaphne. The maximum parsimony and bayesian phylogenetic analyses of the super-matrices of the five chloroplast sequences and the eight concatenated ones, separated the members of both subgenera into two different clades with high bootstrap and posterior probability support, suggesting that the origin of Persea is not monophyletic and therefore both subgenera, Persea and Eriodaphne, could be recognized as phylogenetically independent genera.

In vanilla, compounds that exhibit antimicrobial activity are synthesized; however, the variation in phytochemicals present in the plant structures of this species is little known, in relation to the environmental condition and the crop system. The objective of this research was to quantify the variation in phytochemicals in leaf, stem, flower, green fruit and cured fruit from two vanilla chemotypes (QI and QVI) grown in acahual (native and introduced secondary vegetation) and shade mesh systems. Vanilla chemotypes were collected during the flowering period and at harvest in four locations in the Totonacapan region, Mexico. The concentration of total phenolic compounds, total tannins, hydrolysable tannins, condensed tannins, flavonoids, saponins and triterpenes was analyzed in methanolic extracts by spectrophotometric methods. The phytochemicals accumulated at different concentrations in the vanilla plant tissues in relation to the condition of the crop management system and the chemotype. Acahual cultivation favored the concentration of total phenolic compounds, total, hydrolysable and condensed tannins, and total triterpenes, while the values obtained with shade mesh were higher in saponins. QVI accumulated the highest concentration of phytochemicals, with the exception of hydrolysable tannins that showed no statistical difference between chemotypes. The environmental condition affected the phytochemical concentration of phytochemicals in the plant structures of vanilla. Elevation was the environmental variable that most impacted the accumulation of phytochemicals, since it showed an inverse effect on the concentration of total triterpenes, total tannins and condensed tannins.