Antioxidant Defenses of Plants and Fungi

Dalton, David A.

doi:10.1007/978-1-4615-9689-9_9

Cited by 79 publications

(43 citation statements)

References 188 publications

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“…Insets in each chromatogram show MS analysis data of the indicated peak components. Peak 1 (saponin Aa, m/z = 1365.6) or peak 2 (saponin Ab, m/z = 1437.6) was as well as direct reduction of O 2 by nitrogenase, hydrogenase, and ferredoxin in bacteroids (Dalton, 1995). Ectopic expression of the b-amyrin synthase gene (OXA1) of Aster sedifolius resulted in increased accumulation of triterpene saponins and enhanced root nodulation in barrel medic (Medicago truncatula) (Confalonieri et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

The Sg-1 Glycosyltransferase Locus Regulates Structural Diversity of Triterpenoid Saponins of Soybean

et al. 2012

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Triterpene saponins are a diverse group of biologically functional products in plants. Saponins usually are glycosylated, which gives rise to a wide diversity of structures and functions. In the group A saponins of soybean (Glycine max), differences in the terminal sugar species located on the C-22 sugar chain of an aglycone core, soyasapogenol A, were observed to be under genetic control. Further genetic analyses and mapping revealed that the structural diversity of glycosylation was determined by multiple alleles of a single locus, Sg-1, and led to identification of a UDP-sugar-dependent glycosyltransferase gene (Glyma07g38460). Although their sequences are highly similar and both glycosylate the nonacetylated saponin A0-ag, the Sg-1 a allele encodes the xylosyltransferase UGT73F4, whereas Sg-1 b encodes the glucosyltransferase UGT73F2. Homology models and site-directed mutagenesis analyses showed that Ser-138 in Sg-1 a and Gly-138 in Sg-1 b proteins are crucial residues for their respective sugar donor specificities. Transgenic complementation tests followed by recombinant enzyme assays in vitro demonstrated that sg-1 0 is a loss-of-function allele of Sg-1. Considering that the terminal sugar species in the group A saponins are responsible for the strong bitterness and astringent aftertastes of soybean seeds, our findings herein provide useful tools to improve commercial properties of soybean products.

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Section: Introductionmentioning

confidence: 99%

The Sg-1 Glycosyltransferase Locus Regulates Structural Diversity of Triterpenoid Saponins of Soybean

et al. 2012

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“…In addition, photosynthesis produces singlet oxygen ('O2) through several photochemical and chemical pathways (Asada & Takahashi 1987). Higher plants possess several enzymatic and non-enzymatic scavenging systems for minimizing damage (Ahmad 1995;Dalton 1995). Ascorbate has a central position as an antioxidant in the chloroplast stroma; furthermore, it is essential for the regeneration of a-tocopherol and the deepoxidation of the xanthophyll violaxanthin to zeaxanthin in the thylakoid membrane (Foyer 1993).…”

Section: Introductionmentioning

confidence: 99%

Acclimation by suboptimal growth temperature diminishes photooxidative damage in maize leaves

Leipner

Fracheboud

Stamp

1997

Plant Cell & Environment

109

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Leaves of Zea mays L. seedlings which developed at optimal (25 °C) or suboptimal (15 °C) temperature were exposed to high irradiance (1000/imoI m~^ s~') and a severe chilling temperature (5 °C) for up to 24 h to investigate their ahility to withstand photooxidative stress. During this stress, the degradation of the endogenous antioxidants ascorbate, glutathione and a-tocopherol was delayed and less pronounced in 15 °C leaves. Similarly, the decline in chlorophyll a, chlorophyll b, 3-carotene and lutein was slower throughout the stress period. Faster development and a higher level of non-photochemical quenching (NPQ) of chlorophyll fluorescence, related to a stronger de-epoxidation of the larger xanthophyll cycle pool in 15 °C leaves, could act as a defence mechanism to reduce the formation of reactive oxygen species during severe chilling. Furthermore, plants grown at suboptimal temperature exhibited a higher amount of the antioxidants glutathione and a-tocopherol. The higher a-tocopherol content in leaves (double based on leaf area; 4-fold higher based on chlorophyll content) which developed at suboptimal temperature may play an especially important role in the stabilization of the thylakoid membrane and thus prevent lipid peroxidation.

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“…To determine definitively whether DNA was cleaved by chilling, future studies may be required. The chloroplasts, the nucleus, the mitochondria and the microbodies that were injured by the chilling treatment contain a lot of oxygen radical scavenger [1]. On another line of the Saintpaulia chilling study, 02 absorption instead of 02 release by photosynthesis was observed right after the chilling treatment [17].…”

Section: Resultsmentioning

confidence: 97%

“…The irreversible acute morphological changes and photosynthetic damages in chilling-injured palisade cells of Saintpaulia induced by a rapid drop in leaf temperature were different from the reversible slow changes of chilling injury observed in other cold sensitive plants [17,18]. There are reports [1,19] that enhancement of oxygen radical production was related to chilling injury. Failure to quench free oxygen radical and/or protect from the subsequent propagation chain reactions leads to the extensive degeneration of chromatin and membrane systems.…”

Section: Introductionmentioning

confidence: 93%

Production of Radicals and Acute Apoptotic Changes of Palisade Cells in Early Steps of Saintpaulia Leaf Spot Appearance.

Yasuda

Yun

Miyoshi

et al. 1997

Acta Histochem. Cytochem

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Antioxidant Defenses of Plants and Fungi

Cited by 79 publications

References 188 publications

The Sg-1 Glycosyltransferase Locus Regulates Structural Diversity of Triterpenoid Saponins of Soybean

The Sg-1 Glycosyltransferase Locus Regulates Structural Diversity of Triterpenoid Saponins of Soybean

Acclimation by suboptimal growth temperature diminishes photooxidative damage in maize leaves

Production of Radicals and Acute Apoptotic Changes of Palisade Cells in Early Steps of Saintpaulia Leaf Spot Appearance.

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