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Articles by Miguel Angel Martinez-Tellez
Total Records ( 4 ) for Miguel Angel Martinez-Tellez
  Guillermo O. Perez-Tello , Miguel Angel Martinez-Tellez , Irasema Vargas-Arispuro and Gustavo A. Gonzalez-Aguilar
  Problem statement: Cold storage is needed in order to delay senescence and achieve a longer commercial life of tropical fruits like mamey sapote (Pouteria sapota), therefore, the physiological and biochemical responses of this fruit to cold storage were evaluated.
Approach: Samples from different storage temperature (20, 10 and 2°C) were taken at five-day intervals and Chilling Injury Index (CII), decay (%), pulp firmness, weight loss (%), sucrose, fructose and glucose contents, electrolyte leakage (%), ethylene and carbon dioxide production rates and the activities of Peroxidase (POD), Polyphenoloxidase (PPO) and Phenylalanine Ammonia-Lyasa (PAL), were evaluated.
CII of fruit stored at 2 and 10°C was similar and symptoms included abnormal ripening into trimming zones close to the skin and pulp. Development of CI symptoms was more evident after 10 days of storage at 2 and 10°C. This trend may be associated with decrease of sucrose content but not with fructose that increased on fruits stored at 2°C (p<0.05). For mamey fruits stored at 2°C, the PAL activity was significant lower than in the fruits stored at 10°C, but it did not increase in response to the chilling temperature. No appreciable changes on POD activity were observed in fruit stored at 2°C. PPO activity continuously decreased on fruit stored at 2°C and similar behavior was observed on fruit stored either at 10 and 20°C, during the first 15 days of storage.
Our results demonstrated the sensitivity to mamey sapote fruits to low storage temperatures (2 and 10°C). Symptoms developed by fruit include abnormal ripening into trimming zones close to skin, as well as darkened zones into middle pulp. Sucrose content could be a better chilling injury indicator in mamey sapote than electrolyte leakage, ethylene production and POD, PPO and PAL activities.
  Alejandro B. Falcon-Rodriguez , Juan C. Cabrera , Eduardo Ortega and Miguel Angel Martinez-Tellez
  Problem statement: The chitosan derivatives promote diverse defensive responses in plants, which are affected by chitosan chemical features and concentration. Glucanase (EC, Phenylalanine Ammonia-Lyase (PAL, EC and peroxidase (POD, EC are key enzymes in tobacco defense responses. Thus, the aim of this study was to know the behavior of their enzymatic activity in leaves and roots of whole tobacco plants, previously elicited with chitosan derivatives of different molecular weight and acetylating degree. Approach: 25 day-old tobacco plants were treated with three chitosan derivatives (CH- 63, CH-88 and OLG) of different chemical features. True leaves and roots were sampled after three, six, nine and 12 days post-treatment for further evaluation of the enzymatic activities. Results: Chitosan treatments increased the activity of all three studied enzymes depending on the concentration and chemical feature of the derivative. The highest enzymatic activities with polymers occurred at 1 g L-1 while the oligochitosan mixture achieved good enzymatic levels as compared to controls from 0.1 g L-1 onwards. The Degree of Acetylation (DA) affected PAL activity; a more acetylated polymer induced a higher activity than a less acetylated one. However, the low levels of acetylation favored POD activity. The systemic induction of enzymatic activities was detected in leaves of treated plants after root application. The effect of the acetylation degree was systemically transmitted to the leaves by POD, but not by PAL activity; so the transmission of the acetylating degree influence beyond the tissue directly elicited by chitosan polymer depended on each enzymatic response tested. Conclusion: This study proved that various chitosan derivatives induced and raised lasting β-1,3-glucanase, PAL and POD activities in tobacco leaves and roots as local or systemic responses, which could lead to the accumulation of secondary metabolites and formation of barriers that all together enhance plant resistance against pathogens.
  Consuelo Corrales-Maldonado , Miguel Angel Martinez-Tellez , Alfonso A. Gardea , Antonio Orozco-Avitia and Irasema Vargas-Arispuro
  Problem statement: In warm-winter regions, the need for intervention of chemical means to break bud rest becomes a dominant factor for maintaining economic production of table grapes. However, the problem is more acute when farmers want to grow organic table grapes in the absence of environmentally-friendly budbreak promoters. Approach: This study aimed to evaluate the effect of a mix of naturally occurring Garlic Compounds (GC) in comparison to the conventional use of hydrogen cyanamide to promote budbreak and its effects on cluster quality in four table grape cultivars field-grown in hot region (Sonora Desert). Results: Four cultivars responded to GC, the vines bursting bud about 3 weeks after application. Quality of fruit from 4 cultivars treated with GC was excellent. Clusters weigh and berry sizes were larger than other treatments. Conclusion: Ability of GC to break dormancy in table grape grown in Sonora Desert has significant implications for organic table grape production in hot regions.
  Laura E. Gayosso-Garcia Sancho , Elhadi M. Yahia , Miguel Angel Martinez-Tellez and Gustavo Adolfo Gonzalez-Aguilar
  Problem statement: Nowadays, the worldwide increase in diseases has motivated consumers to increase the intake of fruits and vegetables, in response to various research reports indicating that fruits and vegetables can help prevent certain types of illnesses, due to their potentially high antioxidant properties. We evaluated the effect of the stage of ripeness of papaya fruit (Carica papaya L.) on the contents of bioactive components and their relation with antioxidant capacity. Approach: Whole papaya fruit were selected based on their visual ripeness, classifying them in four stages of ripeness (R1, R2, R3 and R4). Physiological and physical-chemical analysis performed included respiration, production of ethylene, firmness, pH, titratable acidity and total soluble solids, color (L*, a*, b*, °Hue, C); Polygalacturonase (PG) and Pectin Methyl Esterase (PME) activity, total phenolic content and antioxidant capacity (measured using DPPH, TEAC and ORAC assays). Results: The antioxidant capacity decreased approximately 27% in the RS4 when using DPPH and TEAC and increased when using ORAC (60.9%). PG activity increased from 8.14 (in RS1)-22.48 U gFW-1 (in RS4) as the stage of ripeness of papaya fruit increased. PME was affected in a similar manner with an activity of 0.5562 U gFW-1, at the end of the ripening storage. A high correlation between PG activity and softening of ripen papayas was observed. Conclusion/Recommendations: It was observed that papaya fruit experienced changes in firmness, which is correlated with activity from two of the main enzymes: PG and PME and with the increase of respiration and production of ethylene. The various stages of ripeness showed very good antioxidant capacity, being higher in RS1, which is correlated with the higher content of phenolic contents found in this ripening stage.
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