Cereal ?-amylase: Immunochemical study on two enzyme-deficient inbred lines of rye

Daussant, J.; Zbaszyniak, B.; Sadowski, Jan; Wiatroszak, I.

doi:10.1007/bf00387820

Cited by 41 publications

(26 citation statements)

References 8 publications

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“…However, the effects of the available soybean (Hildebrand and Hymowitz, 1981) and rye (Daussant et al, 1981) mutations on vegetative development have not been well characterized. In addition, previously identified Arabidopsis mutants with alterations in ␤-amylase activity carry defects in genes involved in ␤-amylase regulation rather than in ␤-amylase structural genes.…”

Section: Discussionmentioning

confidence: 99%

“…Studies of ␤-amylasedeficient lines of soybean (Glycine max; Hildebrand and Hymowitz, 1981) and rye (Secale cereale; Daussant et al, 1981) have focused primarily on characterizing the effects of reduced ␤-amylase activity on seed formation and germination. These studies reveal no evidence for an essential role of ␤-amylases in carbohydrate metabolism of developing or germinating soybean seeds (Hildebrand and Hymowitz, 1981) or in germination of rye seeds (Daussant et al, 1981). Little work has been done to determine whether the decreased ␤-amylase activity levels in these plant lines affect later, vegetative, stages of development.…”

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confidence: 99%

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The ram1 Mutant of Arabidopsis Exhibits Severely Decreased β-Amylase Activity

2001

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Despite extensive biochemical analyses, the biological function(s) of plant ␤-amylases remains unclear. The fact that ␤-amylases degrade starch in vitro suggests that they may play a role in starch metabolism in vivo. ␤-Amylases have also been suggested to prevent the accumulation of highly polymerized polysaccharides that might otherwise impede flux through phloem sieve pores. The identification and characterization of a mutant of Arabidopsis var. Columbia with greatly reduced levels of ␤-amylase activity is reported here. The reduced ␤-amylase 1 (ram1) mutation lies in the gene encoding the major form of ␤-amylase in Arabidopsis. Although the Arabidopsis genome contains nine known or putative ␤-amylase genes, the fact that the ram1 mutation results in almost complete loss of ␤-amylase activity in rosette leaves and inflorescences (stems) indicates that the gene affected by the ram1 mutation is responsible for most of the ␤-amylase activity present in these tissues. The leaves of ram1 plants accumulate wild-type levels of starch, soluble sugars, anthocyanin, and chlorophyll. Plants carrying the ram1 mutation also exhibit wild-type rates of phloem exudation and of overall growth. These results suggest that little to no ␤-amylase activity is required to maintain normal starch levels, rates of phloem exudation, and overall plant growth.␤-Amylases are found in vegetative tissues as well as in storage and reproductive organs, such as tubers and seeds. ␤-Amylases hydrolyze ␣-1,4-glucosidic linkages from the reducing ends of polysaccharide chains to form maltose (Beck and Ziegler, 1989). The genomes of many plant species contain several genes that encode ␤-amylases. For example, according to the database maintained by The Institute for Genomic Research (TIGR), the Arabidopsis genome includes nine genes that are identified as ␤-amylase or putative ␤-amylase genes (http://www.tigr.org/ tdb/edb2/ath1/htmls/GeneNameSearch.html). Despite the fact that they have been well characterized in vitro, the in vivo biological function(s) of ␤-amylases remains under debate (Ziegler, 1999).Several functions have been proposed for ␤-amylases in vivo. The fact that ␤-amylases hydrolyze starch in vitro (Beck and Ziegler, 1989) suggests a role for ␤-amylases in starch degradation. In addition, immunolocalization studies have shown an apparent association between ␤-amylases and starch granules (Okamoto and Akazawa, 1979;Hagenimana et al., 1992). However, these studies were conducted using polyclonal antibodies that may cross-react with starch phosphorylase. Consequently, the results of these studies should be interpreted with caution (Wang et al., 1995). In addition, starch is localized to plastids, whereas most ␤-amylases lack chloroplast transit peptides (Kreis et al., 1987;Monroe et al., 1991;Yoshida and Nakamura, 1991). Although chloroplast-localized ␤-amylases have been identified (Lao et al., 1999), the majority of ␤-amylase activity is extrachloroplastic (Beck and Ziegler, 1989;Nakamura et al., 1991). For example, 80% of the amylas...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

The ram1 Mutant of Arabidopsis Exhibits Severely Decreased β-Amylase Activity

2001

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“…The mutant line is highly deficient in f3-amylase having less than 1% of the activity present in the normal line kernels. This deficiency is due to a lack of enzymatic protein synthesis (5). In a study on barley mutants exhibiting either a large excess or deficiency in f3-amylase activity, it was shown that two types of mRNA were involved in the synthesis of the endosperm fl-amylase and that the excess or the deficiency was due to a modulation in the endosperm mRNA synthesis (9).…”

Section: Discussionmentioning

confidence: 99%

“…Electrophoresis was carried out at 40C and 5 V cm-' for 15 h. After electrophoresis the gels were stained for amylase activity using soluble starch as substrate (5).…”

Section: Immune Serumsmentioning

confidence: 99%

Independent Regulatory Aspects and Posttranslational Modifications of Two β-Amylases of Rye

Daussant

Sadowski²,

Rorat³

et al. 1991

Plant Physiol.

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We have examined the occurrence/disappearance, tissue location, and posttranslatlonal modification of j-amylase proteins in rye (Secale cere L.) kernels at three physiological stages (development, maturity, germination) with a normal inbred line and a mutant line exhibiting a high but incomplete fl-amylase deficiency. This deficiency corresponds to a lack of accumulation of fl-amylase activity in the endosperm and does not affect the level of activity in the outer pericarp and green tissues as compared to the normal line. Two antigenically related but distinct ,-amylases (I and 11) were detected in the normal line (II being the major constituent) and only one (I) in the mutant line. I and 11 display very similar electrophoretic polymorphism. In both lines, I appears to be ubiquitous, although it disappears from the outer pericarp during ripening. Antigen II was present only in the normal line and appears to be specific for the endosperm and perhaps for the maternal green tissues of the seed. Posttranslational modifications occurring during germination, which are mimicked by the action of papain, affect 11 but not 1. The two groups of 0-amylases are discussed in relation to recent reports indicating the presence of two types of j0-amylase with different functions and gene loci in barley and wheat.fl-Amylases in barley, wheat, and rye kernels are known to consist of several distinct constituents, which nevertheless are antigenically identical and which exhibit a common developmental phenomenology. The enzyme is synthesized in the endosperm ofdeveloping seeds and is stored partly in a bound form which is then posttranslationally modified during germination. The modifications involve proteolytic cleavage (1,2,8,12,15,19

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“…In addition to sweet potato, β-amylase-deficient phenotypes have been identified in soybean Hymowitz 1980, 1981), rye (Daussant et al 1981, Sadowski and Daussant 1989, barley (Kreis et al 1987, Kihara et al 1999, Kaneko et al 2000, rice (Yamaguchi et al 1999), wheat (Allison et al 1978, and Arabidopsis (Laby et al 2001). In most cases, studies of β-amylase null mutants have shown that the differences in enzyme activity lie in the β-amylase genetic structure, but no study has focused on the translational, transcriptional, or genetic structural control of the β-amylase null phenotypes in sweet potato.…”

Section: Introductionmentioning

confidence: 99%

Nucleotide sequence variation associated with .BETA.-amylase deficiency in the sweet potato Ipomoea batatas (L.) Lam

et al. 2009

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Amyβ is a single gene that encodes β-amylase, a starch-hydrolyzing enzyme that confers sweetness to sweet potato roots upon cooking. To clarify the genetic basis underlying β-amylase null activity, we sequenced a highly conserved region of Amyβ, including the Amyβ active center, from normal and null cultivars. Comparison of the sequences revealed the presence of the In-Del sequences in null cultivars, which was thought to be a loss-of-function mutation causing a change from sweet to non-sweet. The In-Del frequency revealed using a multiple sequencing approach, and its association with β-amylase activity, showed that an inactive allele of Amyβ gene (Amyβ-I) exists. Amyβ expression analysis showed that Amyβ-I is transcribed normally, suggesting that translational control of β-amylase activity occurs in null mutants. The insertion in Amyβ-I caused a sequence frameshift resulting in an amino acid substitution with the incorporation of a stop codon in Amyβ-I. The Amyβ-I amino acid substitution and premature termination affect the substrate binding and catalytic site of the enzyme, which may result in an inactive protein that is responsible for the β-amylase inactivity in non-sweet cultivars. These findings are the basis of selection markers for non-sweetness in sweet potato breeding.

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Cereal ?-amylase: Immunochemical study on two enzyme-deficient inbred lines of rye

Cited by 41 publications

References 8 publications

The ram1 Mutant of Arabidopsis Exhibits Severely Decreased β-Amylase Activity

The ram1 Mutant of Arabidopsis Exhibits Severely Decreased β-Amylase Activity

Independent Regulatory Aspects and Posttranslational Modifications of Two β-Amylases of Rye

Nucleotide sequence variation associated with .BETA.-amylase deficiency in the sweet potato Ipomoea batatas (L.) Lam

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