ascorbic-acid and 1-naphthaleneacetic-acid

Two different drought tolerance soybean ( Glycine max) varieties (Nannong 99-6 and Kefeng 1) were used to study the effects of α-naphthaleneacetic acid (NAA) on the antioxidation system under long-term drought stress after flowering with pot experiment, which lasted for 110 days at Pailou Experiment Station, Nanjing Agricultural University, in 2012. The results showed that long-term stress decreased the shoot dry mass significantly, however, increased the level of reactive oxygen species (ROS) and malondialdehyde (MDA) content. It also obviously increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) , ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), glutathione reductase (GR) and glutathione peroxidase (GPX). The contents of ascorbic acid (AsA) and glutathione (GSH), and the ratios of AsA/DHA (dehydroascorbic acid) and GSH/GSSG (L-glutathione oxidized) were obviously enhanced. Kefeng 1 showed a higher antioxidation ability than Nannong 99-6, and could consequently maintain lower ROS and MDA levels. NAA distinctly enhanced the activities of APX, POD, CAT, MDHAR, GPX, and ratios of AsA/DHA and GSH/GSSG, while decreased the levels of ROS and MDA. The AsA content and dehydroascorbate reductase (DHAR) activity were significantly increased in Kefeng 1.

Topics: Antioxidants; Ascorbate Peroxidases; Ascorbic Acid; Catalase; Docosahexaenoic Acids; Droughts; Flowers; Glutathione; Glutathione Peroxidase; Glycine max; Malondialdehyde; NADH, NADPH Oxidoreductases; Naphthaleneacetic Acids; Plant Leaves; Reactive Oxygen Species; Stress, Physiological; Superoxide Dismutase

The function of the apoplastic enzyme ascorbate oxidase (AO) was investigated in tobacco (Nicotiana tabacum). The abundance of AO mRNA was up-regulated by light. Cytosolic ascorbate peroxidase (APX1) transcripts were also highest in the light. In contrast, L-galactono-gamma-lactone dehydrogenase, stromal APX, and thylakoid APX transcripts remained constant over the day/night cycle. Salicylic acid inhibited growth, increased expression of the pathogenesis-related protein (PR) 1a, and decreased AO transcript abundance. In contrast, the application of auxin enhanced growth and increased AO and PR 1a gene expression. Therefore, AO transcript abundance varied in a manner similar to hormone-mediated changes in plant growth. To study the effects of modified AO expression on growth, transformed tobacco plants expressing AO in the sense and antisense orientations were generated. The resultant large changes in apoplastic AO activity in the transformed tobacco plants had little effect on whole leaf ascorbate (AA) content, but they had dramatic effects on apoplastic AA levels. Enhanced AO activity oxidized the apoplastic AA pool, whereas decreased AO activity increased the amount of AA compared with dehydroascorbate. A relationship was observed between AO activity and plant height and biomass. Native AO transcript levels were no longer subject to light/dark regulation in AO sense and antisense plants. Taken together, these data show that there is an interaction between hormone, redox, and light signals at the level of the apoplast via modulation of ion of AA content.

Topics: Abscisic Acid; Ascorbate Oxidase; Ascorbic Acid; Circadian Rhythm; Darkness; Gene Expression; Gene Expression Regulation, Plant; Indoleacetic Acids; Light; Naphthaleneacetic Acids; Nicotiana; Phenotype; Plant Leaves; Plants, Genetically Modified; RNA, Messenger; RNA, Plant; Salicylic Acid