Humberto Antonio López-Delgado

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Increased oxidative stress displayed during dark-senescence of wheat leaves (Triticum aestivum L.) is caused not only by the increased levels of radicals but also by a loss of antioxidant capacity. Mature leaves were incubated in 6-benzylaminopurine (BAP 10(-4)M) or water (control) during 6d in the dark. The senescence-delaying effect of BAP was associated(More)
Acetylsalicylic acid was investigated as an alternative medium supplement to mannitol for slow-growth in vitro storage of potato microplants. At 8°C, culture in the presence of either 100 μM acetylsalicylic acid or 4% mannitolretarded microplant stem growth, and required intervals between subcultures ranged from 8 to over 12 months, depending on the(More)
A modification of the standard thermotherapy used to eliminate virus from potato virus X (PVX)-infectedSolanum tuberosum microplants of the Mexican National Potato Program is described here. Microplants were cultured with or without 10-5 M salicylic acid (SA) for 4 wk, then subcultured without SA and exposed to 42 C for 30 days. Survival was more consistent(More)
A model based on thein vitro-to-glasshouse system used in potato seed production programs was implemented to investigate the effects of abscisic acid (ABA) on the induction of freezing tolerance in microplants of two potato cultivars with different sensitivity. Microplants 28 days old, cultured in the presence of ABA, were transferred to soil and exposed to(More)
Field-grown potato plants were sprayed twice weekly, from 21 to 90 days after planting, with 5 or 50 mM hydrogen peroxide (H2O2) solutions. Relative to water-sprayed controls, the H2O2 treatments significantly enhanced tuber starch accumulation by between 6.7% and 30%, as determined by specific gravity or the anthrone spectrophotometric method. Pronounced(More)
During a pathogen attack, cells triggers the overproduction of reactive oxygen species causing oxidative stress and physiological damage. Plants develop strategies using these reactive molecules for protection against pathogen attack. Phytoplasma are bacteria lacking cell walls that inhabit plant phloem and reduce yield, tuber quality, and commercial(More)
This research evaluated the effects of arbuscular mycorrhizal fungi (AMF) on growth, nutritional status, total antioxidant activity (AOX), total soluble phenolics content (TPC), and total nitrate reductase activity (NRA) of leaves and roots of Melilotus albus Medik planted in diesel-contaminated sand (7500 mg kg(-1)). Seedlings of Melilotus either Non(More)
Phytoplasmal infections cause loss in yield, quality and germination of tubers. Hydrogen peroxide and antioxidants such as ascorbic acid and dehydroascorbate are implicated in signaling against stress. The effects of these chemicals on minituber yield, sprouting and starch content were evaluated in plants testing positive for phytoplasma. Without chemical(More)
Salicylic acid (SA) and hydrogen peroxide (H2O2) are involved in similar signaling responses to stress. Previous reports demonstrated micro-tuberization induction by salicylates. Both SA and H2O2 induce similar long term signaling responses to stress. In the present work, the potential long term effect of H2O2 on the induction of micro-tuberization was(More)
H2O2-mediated symptoms and antioxidant responses were examined in phytoplasma-infected potato plants under drought conditions. In vitro phytoplasma-infected or uninfected plants were transferred to a greenhouse and sprayed twice a week with H2O2. Phytoplasma decreased water potential, catalase (CAT) activity and increased H2O2 content significantly. H2O2(More)