Characterization and distribution of an interspersed repeated nucleotide sequence from Lophopyrum elongatum and mapping of a segregation-distortion factor with it

Abstract

Repeated nucleotide sequence pLeUCD2 cloned from Lophopyrum elongatum is highly abundant in the genomes of diploid and polyploid wheatgrass species of genera Lophopyrum, Thinopyrum, Pseudoroegneria, Agropyron, Elymus, Elytrigia, and Pascopyrum but undetectable by Southern blot hybridization in Triticum and representative species of Dasypyrum, Hordeum, Psathyrostachys, Secale, Taeniatherum, Heteranthelium, and Leymus in the tribe Triticeae. The DNA fragment inserted in pLeUCD2 is 277 bp long and AT rich (65%), and contains numerous inverted and palindromic repeats. In situ DNA hybridization substantiated a previous hypothesis that the sequence is interspersed in the wheatgrass genomes. Heterogeneity and clustering of like repeats of the pLeUCD2 family along wheatgrass chromosomes was used to map a segregation-distortion factor, designated Sd-1, proximal to the Lr19 locus in recombinant chromosomes of L. ponticum chromosome 7Ag and wheat chromosome 7D.

Molecular characterization of durum and common wheat recombinant lines carrying leaf rust resistance (Lr19) and yellow pigment (Y) genes from Lophopyrum ponticum

“…This locus was mapped proximal to Lr19 (Zhang and Dvorak 1990), between the centromere and Xpsr165 (Prins et al 1996). We observed a similar preferential transmission in the recombinant lines carrying the proximal part of the 7DSAE7DL-7EL#1, confirming its proximal location.…”

“…He produced ten new 7D-7E recombinant lines with smaller 7E segments and observed that chromosomes with longer 7E segments were preferentially transmitted through the pollen (Sears 1977). Zhang and Dvorak (1990) later found that the Sd1 locus was responsible for this preferential transmission and that it was proximal to Lr19.…”

Chromosome characterization in Thinopyrum ponticum (Triticeae, Poaceae) using in situ hybridization with different DNA sequences

“…Highly repetitive DNA sequences, such as pSc119.2 cloned from rye (Lapitan et al, 1987) and pLeUCD2 of Th. elongatum (Zhang and Dvorák, 1990;Kim et al, 1993), have been isolated and used in the characterization of Thinopyrum chromosomes and for the identification of introgressed alien chromatin in wheat x Thinopyrum hybrids. In the present study, FISH was used to identify the number and position of 45S and 5S rDNA sequences, as well as the distribution of the highly repetitive DNA sequences pAs1 and pSc119.2 in the Th.…”

Genomes, Chromosomes and Genes of the Wheatgrass Genus Thinopyrum: the Value of their Transfer into Wheat for Gains in Cytogenomic Knowledge and Sustainable Breeding

“…Although their use in breeding was hampered by negative effects caused by the presence of at least one Sd gene ; see also ahead, § 14.4.3), they represented valuable materials to assign the critical alien genes and a number of molecular markers of the RFLP type to defined intervals along the 7el 1 L arm, hence to start assessing its synteny and colinearity with wheat 7L arms. Previously, the first series of 7AgL (= 7el 1 L)-7DL homoeologous recombinants (Sears 1973(Sears , 1978 had been discriminated on the basis of their Lr19 and Sd phenotypes, combined with results of meiotic pairing analyses and of the distribution pattern of a Thinopyrum-specific repetitive sequence (Zhang and Dvorak 1990). Based on these parameters, only an indirect and comparative estimate of the relative length of the alien and wheat chromosome segments in the individual recombinant chromosomes could be established.…”