Extreme divergence of a novel wheat thionin generated by a mutational burst specifically affecting the mature protein domain of the precursor

A new type of neutral thionin (type V), specifically expressed in developing wheat endosperm, has been found to be encoded by a set of single-copy genes located in the long arms of chromosomes 1A, 1B and 1D, within less than 10,000 base-pairs of those corresponding to the highly basic type-I thionins. Divergence between types I and V has occurred through a process of accelerated evolution that has affected the amino acid sequence of the mature thionin but not the precursor domains corresponding to the N-terminal signal peptide and the long C-terminal acidic peptide. This process involved a deletion and a non-synonymous nucleotide substitution rate equal to the synonymous rate in the thionin sequence

Nucleotide sequence of a cDNA encoding an α/β-type gliadin from hexaploid wheat (Triticum aestivum).

A cDNA clone was isolated from a library obtained from developing endosperm of cv. Chinese Spring which encoded an α/β-type gliadin that differs from previously described ones. The nucleotide sequence and deduced amino acid sequence of the new clone, designated MM1, are presented

Signal peptide homology between the sweet protein thaumatin II and unrelated cereal α-amylase/trypsin inhibitors

A cDNA clone (pUP-23) corresponding to a member of a protein family that includes inhibitors of trypsin and of heterologous α-amylases has been selected from a library derived from developing barley endosperm and its sequence has been determined. A stretch of 95 nucleotides that included the signal peptide and the first 8 residues of the mature protein was found to be homologous to an exactly equivalent region of the nucleotide sequence encoding the sweet protein thaumatin II. Evolutionary implications of this finding are discussed

Equivalent locations of sucrose synthase genes in chromosomes 7D of wheat, 7Ag of Agropyron elongatum, and 7H of barley

Wheat/Agropyron 7D/7Ag recombinant chromosomes were analysed by Southern blotting, using cDNA radioactive probes corresponding to the Ssl and Ss2 sucrose synthase genes of wheat. The genes were located in the central segments of the short arms of both chromosomes 7D and 7Ag. A similar analysis of wheat/barley addition lines demonstrated that DNA sequences that cross-hybridized with the wheat probes were located in chromosome 7H of barley

Equivalent locations of sucrose synthase genes in chromosomes 7D of wheat, 7Ag of Agropyron elongatum, and 7H of barley

Wheat/Agropyron 7D/7Ag recombinant chromosomes were analysed by Southern blotting, using cDNA radioactive probes corresponding to the Ss1 and Ss2 sucrose synthase genes of wheat. The genes were located in the central segments of the short arms of both chromosomes 7D and 7Ag. A similar analysis of wheat/barley addition lines demonstrated that DNA sequences that cross-hybridized with the wheat probes were located in chromosome 7H of barley

The thionins: a protein family that includes purothionins, viscotoxins and crambins

Almost half a century ago, a crystalline protein material was obtained from lipid extracts of wheat endosperm and designated "purothionin" (Trvpwo, wheat; 9 e i w v , sulphur) on account of its high sulphur content (Balls et al., 1942a,b). This material, which was thought to be the oxidized form of a powerful oxidation-reduction system, was found to have baetericidal and fungicidal properties (Stuart and Harris, 1942), to inhibit fermentation of wheat mashes (Balls and Harris, 1944), and to be toxic to laboratory animáis (Coulson et al., 1942)

Extreme variations in the ratios of non-synonymous to synonymous nucleotide substitution rates in signal peptide evolution

Nucleotide sequences encoding signal peptides from the precursors of 2-amylase/trypsin inhibitors from cereals are homologous to those corresponding to the precursors of thaumatin II and of plastocyanins. Non-synonymous (K A ) and synonymous {K % ) rates of nucleotide substitutions have been calculated for all possible binary combinations. Extreme variation in A' A^S ratios has been observed; from the 0.167 average found within the plastocyanin family to an average of 1.90 calculated for the inhibitors/thaumatin II transition. A similar calculation has been carried out for the signal peptide sequences of thionins. which are unrelated to those of the a-amylase trypsin inhibitor family. and an average /í A //w s of 0.12 has been obtained. This variation can be largely explained in terms of an empirical index of stability related to amino acid composition and seems to be independent of functional constraints. ot-Amylase;trypsin inhibitor; Thaumatin II; Thionin; Plastocyanin; Signal peptide evolutio

Linked sucrose synthase genes in group-7 chromosomes in hexaploid wheat (Triticum aestivum L.)

A cDNA library from developing wheat endosperm was screened for sucrose-synthase clones using a maize cDNA probe corresponding to the Sh1 locus under non-stringent conditions. Five positive clones were isolated and initially classified into two types on the basis of their relative ability to hybridize with the probe and of their partial restriction maps. Determination of the nucleotide sequences indicated homology between the two types of wheat clones, with type 1 showing higher homology to the maize Sh1 locus than to type-2 sequences. The inserts cloned in plasmids pST8 (type 1) and pST3 (type 2) were used as probes to determine the chromosomal locations of the two types of genes. DNAs from compensated nulli-tetrasomic and ditelosomic lines of wheat cultivar Chinese Spring were cleaved with EcoRI and analysed in Southern blots. DNA segments of the two types were thus identified in the short arms of chromosomes 7A, 7D, and, possibly, 7B. The two types of linked loci have been designated Ss1 and Ss2, respectivel

Extreme variations in the ratios of non-synonymous to synonymous nucleotide substitution rates in signal peptide evolution

Nucleotide sequences encoding signal peptidcs from the precursors of α-amylase/trypsin inhibitors from cereals are homologous to those corresponding to the precursors of thaumatin II and of plastocyanins. Non-synonymous (KA) and synonymous (KS) rates of nucleotide substitutions have been calculated for all possible binary combinations. Extreme variation in KA/KS ratios has been observed, from the 0.167 average found within the plastocyanin family to an average of 1.90 calculated for the inhibitors/thaumatin II transition. A similar calculation has been carried out for the signal peptide sequences of thionins. which are unrelated to those of the α-amylase trypsin inhibitor family, and an average KA/KS of 0.12 has been obtained. This variation can be largely explained in terms of an empirical index of stability related to amino acid composition and seems to be independent of functional constraints

Cultura y desarrollo sostenible : aportaciones al debate sobre la dimensión cultural de la Agenda 2030

Incluye biografías de los autoresEl presente documento se ha redactado en base a dos sesiones de trabajo, celebradas los días 27 noviembre de 2019 y 4 de marzo de 2020, y en debates en foros on line, en las que han participado miembros del grupo Cultura y Desarrollo Sostenible