Mutant Gene That Changes Protein Composition and Increases Lysine Content of Maize Endosperm

Mertz, Edwin T.; Bates, L. S.; Nelson, Oliver E.

doi:10.1126/science.145.3629.279

Cited by 977 publications

(500 citation statements)

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“…In the W64A background, o2 appeared as a spontaneous mutation (actual isogenic lines). In F2, the original o2 allele, studied by Mertz (Mertz et a!., 1964), was introgressed by eight generations of backcross (near-isogenic lines The pis of the polypeptides in the most acidic pH range were determined from IEF gels cut into 1-cm long pieces crushed in degassed distilled water. The pHs of the successive mixtures were used to plot a standard curve.…”

Section: Plant Materialsmentioning

confidence: 99%

Quantification of dominance for proteins pleiotropically affected by opaque-2 in maize

Damerval

Vienne

1993

Heredity

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The maize opaque-2 (o2) mutation is known to have numerous pleiotropic effects. Using two different genetic backgrounds, endosperm proteins from isogenic lines of the o2 locus and their reciprocal hybrids were compared by high-resolution two-dimensional electrophoresis (2-D PAGE), and the 2-D gels stained with Coomassie blue or silver were analysed using a computerassisted system for quantification of polypeptide spots. The aim of this work was (i) to identify polypeptides, the amount of which is affected by the single gene substitution, and (ii) to assess the dominance relations for every affected polypeptide. The triploid nature of the endosperm allowed the effects of 0, 1, 2 and3 doses of the wild-type 02 allele to be examined. When using a basic pH range in the first dimension (IEF), we observed the known effects of o2 on prolamin storage proteins, mostly being 22 kDa, zeins. In a pH 5-7 IEF range, we detected 14 polypeptides whose amount is affected by the o2 mutation in both backgrounds. Eight of them were more abundant in the wild type than in the mutant and six were more abundant in the mutant than in the wild type. Dominance of the wild type allele was found for the amounts of 10 polypeptides, while the amounts of two of them displayed additive inheritance. This is an example where pleiotropically related characters display different inheritance, which could generate heterozygous phenotypes with original properties as compared to their homozygous parents. Because 02 belongs to the basic region-leucine zipper family of transcription activators, our results show that 2-D PAGE of isogenic lines represents a straightforward method to identify gene products affected by a transcription factor, whether they are products of its target genes, or products indirectly affected by far-reaching effects. This is a prerequisite to understanding the multiple molecular and physiological consequences of the action of such factors.Keywords: dominance, isogenic lines, maize, opaque-2, plelotropy. IntroductionNumerous single mutations are known that have multiple phenotypic consequences (Caspari, 1952;Wright, 1968). Various mechanisms can be put forward to explain pleiotropy. For example, a mutation of a gene coding for a trans-acting transcription factor binding to the promoter regions of different genes could result in variation of the characters they control (Hope & Struhl, 1985;Sassone-Corsi, 1985). At the post-translational level, it has been shown that differences in the degree of sialylation of multiple hydrolases could be due to the mutation of the gene coding for neuraminidase (Womack et at., 1981). Keightley & Kacser (1987) investigated a branched metabolic pathway where the two outputs represent two characters whose variation is affected by changes in any of the genetically specified enzymes in the system. However, characterization of the mutation may not be sufficient 38 to predict or understand all the diverse pleiotropic effects. Recent cloning of the r (rugosus) gene in pea revealed that it encodes a starch-br...

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Section: Plant Materialsmentioning

confidence: 99%

Quantification of dominance for proteins pleiotropically affected by opaque-2 in maize

Damerval

Vienne

1993

Heredity

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“…Such dependence on maize as the primary or only protein source can lead to protein-energy malnutrition because of its inherent deficiency in two essential amino acids, lysine and tryptophan (Nelson 1969;WHO 2000;Bright and Shwery 1983). Efforts to improve protein quality in maize led to the discovery of opaque-2 mutants, which have increased lysine and tryptophan content (Mertz et al 1964). The original opaque-2 allele was associated with reduction in yield and poor kernel characteristics (Salamini et al 1970).…”

Section: Introductionmentioning

confidence: 99%

Genetic analysis of tropical quality protein maize (Zea mays L.) germplasm

et al. 2017

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Maize (Zea mays L.) is an important source of carbohydrates and protein in the diet in sub-Saharan Africa. The objectives of this study were to (i) estimate general (GCA) and specific combining abilities (SCA) of 13 new quality protein maize (QPM) lines in a diallel under stress and non-stress conditions, (ii) compare observed and predicted performance of QPM hybrids, (iii) characterize genetic diversity among the 13 QPM lines using single nucleotide polymorphism (SNP) markers and assess the relationship between genetic distance and hybrid performance, and (iv) assess diversity and population structure in 116 new QPM inbred lines as compared to eight older tropical QPM lines and 15 non-QPM lines. The GCA and SCA effects were significant for most traits under optimal conditions, indicating that both additive and non-additive genetic effects were important for inheritance of the traits. Additive genetic effects appeared to govern inheritance of most traits under optimal conditions and across environments. Non-additive genetic effects were more important for inheritance of grain yield but additive effects controlled most agronomic traits under drought stress conditions. Inbred lines CKL08056, CKL07292, and CKL07001 had desirable GCA effects for grain yield across drought stress and non-stress conditions. Prediction efficiency for grain yield was highest under optimal conditions. The classification of 139 inbred lines with 95 SNPs generated six clusters, four of which contained 10 or fewer lines, and 16 lines of mixed co-ancestry. There was good agreement between Neighbor Joining dendrogram and Structure classification. The QPM lines used in the diallel were nearly uniformly spread throughout the dendrogram. There was no relationship between genetic distance and grain yield in either the optimal or stressed environments in this study. The genetic diversity in mid-altitude maize germplasm is ample, and the addition of the QPM germplasm did not increase it measurably.

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“…O isolamento de mutantes naturais apresentou-se como uma primeira alternativa de progresso significativo. A identificação do mutante opaco-2 (o2) de milho (Mertz et al, 1964) e do mutante de cevada Hiproly (lys1) para alta lisina (Munck, 1992) foi uma descoberta importante que traçou rumos de pesquisas desde então. Contudo, após a euforia inicial devida à alta concentração de lisina dos mutantes, seguiu-se um grande desapontamento pela associação nestes mutantes, de características agronômicas indesejáveis como queda de produção e alta susceptibilidade a patógenos.…”

Section: Mutantes Bioquímicos E Plantas Transgênicasunclassified

Manipulação de cereais para acúmulo de lisina em sementes

Molina

Gaziola

Lea

et al. 2001

Sci. agric. (Piracicaba, Braz.)

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RESUMO: A lisina é um aminoácido essencial cuja via de biossíntese faz parte da via metabólica do ácido aspártico, pela qual são também sintetizados os aminoácidos treonina, metionina e isoleucina. Além disso, a lisina é o principal aminoácido limitante em todos os cereais e por cerca de 30 anos a via do ácido aspártico tem sido estudada em plantas, com o intuito de desvendar e caracterizar os principais pontos chave na regulação das vias de biossíntese desses aminoácidos. Duas etapas distintas, uma primeira originada a partir do desenvolvimento da cultura de tecidos (anos 70-80) e a segunda a partir do desenvolvimento de técnicas para a transformação de plantas (anos 90), permitiram que mutantes bioquímicos e plantas trangênicas fossem produzidos com alterações específicas em passos metabólicos chave, levando à superprodução e acúmulo de treonina em vários tecidos das plantas. Entretanto, a acumulação de lisina em sementes não foi obtida. Tal fato, associado a estudos bioquímicos da via de degradação da lisina em cereais e em leguminosas, indicou que a manipulação da degradação seria tão ou mais importante que a manipulação da biossíntese de lisina para o acúmulo deste aminoácido em sementes dos cereais . Em milho, o uso e estudo de outros mutantes tais como o opaco-2 e variedades QPM (Quality Protein Maize) contribuíram significativamente para a compreensão dos eventos regulatórios. As estratégias para a obtenção de materiais ricos em lisina e sua relevância à manipulação de outros aminoácidos são revisados. Palavras-chave: lisina, nutrição, aminoácidos essenciais, cereais MANIPULATING CEREAL CROPS FOR HIGH LYSINE ACCUMULATION IN SEEDSABSTRACT: The nutrition value of a protein is directly related to its amino acid composition. Some of these amino acids, termed essential amino acids, cannot be synthesized by humans and therefore must be supplied in the diet for adults and in particular for infants and children. Lysine is an essential amino acid synthesized via the aspartic acid metabolic pathway, in which threonine, methionine and isoleucine are also endproducts. Moreover, lysine is the first limiting amino acid in all cereal grains. For over 30 years, the aspartic acid metabolic pathway has been studied in higher plants with the aim of identifying and characterizing the key regulatory points controlling the biosynthetic pathway. Two clear distinct time periods, one begining with the development of tissue culture techniques (1970-80's) and the second with the development of plant transformation techniques (90's), has encouraged the production of biochemical mutants and transgenic plants with specific alterations in key enzymes of the pathway, leading to the overproduction and accumulation of threonine in all plant tissues. However, the accumulation of lysine in seeds has been particularly difficult to achieve. Such an observation, associated with the recent biochemical studies on lysine degradation in cereal and legume plant species, has indicated that the manipulation of lysine degradation is as important as t...

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Mutant Gene That Changes Protein Composition and Increases Lysine Content of Maize Endosperm

Cited by 977 publications

References 1 publication

Quantification of dominance for proteins pleiotropically affected by opaque-2 in maize

Quantification of dominance for proteins pleiotropically affected by opaque-2 in maize

Genetic analysis of tropical quality protein maize (Zea mays L.) germplasm

Manipulação de cereais para acúmulo de lisina em sementes

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