Sharp divergence between wheat and barley at loci encoding novel members of the trypsin/alpha-amylase inhibitors family.
Amino acid sequences for three members (CMx1, CMx2, and CMx3) of a new subfamily of trypsin/alpha-amylase inhibitors in wheat have been deduced from the nucleotide sequences of the corresponding cDNAs. A cDNA clone encoding CMx1 was selected from a wheat developing endosperm library using a probe that encoded barley trypsin inhibitor BTI-CMe at low stringency. Sequences corresponding to CMx2 and CMx3 were obtained from cDNA amplified by the polymerase chain reaction. The three CMx sequences contain a premature stop codon after 363 nt, as well as a second stop codon at the same position as in BTI-CMe (nt 439-441). Southern analysis of DNAs from diploid, tetraploid, and hexaploid wheats, as well as from aneuploid lines, indicate that there is a single CMx locus in each of the three genomes of hexaploid wheat, respectively associated with chromosomal arms 4AS, 4BS, and 4DL. These genes are expressed early during endosperm development and not expressed at detectable levels in other tissues. Evolutionary implications are discussed.
Sanchez de la Hoz
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Departamento de Biotecnología, ETS Ingenieros Agrónomos-UPM, Madrid, Spain.
Castagnaro
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Carbonero
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000235:genetics; D015723:Gene Library; D017343:Genes, Plant / Q000235:genetics; D001467:Hordeum / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics; D011003:Ploidies; D012639:Seeds / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014908:Triticum / Q000235:genetics*; D014361:Trypsin Inhibitors / Q000235:genetics*; D000516:alpha-Amylases / Q000037:antagonists & inhibitors*
D018076:DNA, Complementary; D010940:Plant Proteins; D014361:Trypsin Inhibitors; C060586:WDAI-3 protein, Triticum aestivum; D000516:alpha-Amylases