ABSTRACT
MtDNA restriction fragment polymorphisms were found between cytoplasmic male-sterility types P and R of Plantago lanceolata with the homologous probe pPl311 and maize mtDNA fragments derived from the regions of atp1, cox1 and cox2. No mtDNA differences were observed between male- sterile and restored plants with the same cytoplasmic type. The con-sistency of the polymorphisms was studied in 83 plants from 24 natural populations in the Netherlands. Within the R-cytoplasm no mtDNA polymorphisms were found, whereas seven variant mtDNA RFLP patterns were observed within the P-cytoplasm using pPl311. We also report on a putative new cytoplasmic male-sterility type, which showed a unique RFLP pattern supporting its distinct status.
ABSTRACT
The distribution of two repetitive DNA probes Sat-121 and PB6-4, specific for the section Procumbentes of the genus Beta, was tested in 16 B. patellaris monosomic addition families using a dot-blot hybridization procedure. All monosomic additions were accurately distinguished from diploid sib plants with both DNA probes. The probe PB6-4, with the strongest signal after hybridization, was selected for rapid screening of an extensive number of putative monosomic additions in B. patellaris or B. procumbens addition families using a squash-blot hybridization procedure. The probe PB6-4 detected 118 monosomic additions in 640 plants (18.4%) in eight different B. procumbens addition families. The addition family with chromosome 4 of B. procumbens was semi-lethal and could not be tested. The distribution of PB6-4 in B. patellaris addition families was confirmed in 63 addition families using the squash-blot procedure. In 4580 plants of these addition families, 628 individual monosomic additions (13.7%) were found. The relationship of the morphological characteristics of monosomic addition plants to the results of the squash-blot hybridization (plants with signal) using probe PB6-4 is quite rigorous but not complete. The correlation between plants with a signal and chromosome number (2n=19) is complete. These results indicate that sequences present on PB6-4 are probably present on all chromosomes of B. patellaris and B. procumbens. The possibility of utilizing the sequence information of Sat-121 for a PCR-based assay to screen for putative monosomic addition plants was also investigated as an alternative to chromosome counting. The DNA-amplification profiles using the primers REP and REP.INV clearly distinguished monosomic addition plants from their diploid sibs.
ABSTRACT
A backcross population of the L. peruvianum accession LA 2157, which is resistant to bacterial canker caused by Clavibacter michiganensis ssp. michiganensis, with the susceptible L. peruvianum accession LA 2172 was evaluated for the segregation of C. michiganenis resistance and of RFLP markers in order to map the loci involved in this resistance. The development of symptoms of the disease was scored using an ordinal scale. The mapping of the disease resistance was hampered by distorted segregation ratios of a large number of markers and unexpected quantitative inheritance of the resistance. By means of the Kruskal-Wallis rank-sum test, five regions on chromosomes 1, 6, 7, 8 and 10 were identified that may be involved in C. michiganensis resistance.
ABSTRACT
Universal primers were used for PCR amplification of three noncoding regions of chloroplast DNA (cpDNA) in order to study sequence-length variation in the Crassulaceae and in related species. Several length mutations were observed that are of diagnostic value for evolutionary relationships in the Crassulaceae and the Saxifragaceae. Length variation and sequence divergence in the intergenic spacer between the trnL (UAA) 3' exon and the trnF (GAA) gene among 15 species were studied in detail by nucleotide-sequence analysis. A total of 50 insertion/deletion mutations were observed, accounting for a spacer-length variation in the range of 228-360 bp. Eighteen short direct repeat motifs (4-11 bp) and two inverted repeat motifs (7-11 bp) were found to be associated with length variation. Phylogenetic analysis of the sequence data indicated a pattern of relationships that was largely consistent with a previous analysis of cpDNA restriction-site variation. Evaluation of the level of homoplasy in insertion/deletion mutations within a phylogenetic framework revealed that only 1 out of 34 length mutations longer than 2 bp must have had multiple origins. The feasibility of the noncoding chloroplast DNA regions for molecular evolutionary studies is discussed.
Subject(s)
Chloroplasts , Phylogeny , Plants/genetics , Base Sequence , Genetic Markers , Molecular Sequence Data , Plants, Toxic , Polymerase Chain Reaction , Sequence Alignment , Sequence Homology, Nucleic Acid , Species Specificity , Nicotiana/geneticsABSTRACT
In order to map genes determining resistance to bacterial canker in tomato, backcrosses were made between a resistant and a susceptible Lycopersicon peruvianum accession. The linkage study with RFLP markers yielded a genetic map of L. Peruvianum. This map was compared to that derived from a L. esculentum x L. pennellii F2 population, based on 70 shared RFLP markers. The maps showed a good resemblance in both the order of markers and the length of the chromosomes, with the exception of just one relocated marker on chromosome 9. Because backcrosses were made with the F1, either as the pollen parent or as the pistil parent, linkage maps from male and female meioses could be estimated. It was concluded that recombination at male meiosis was reduced, and that gametophytic selection for parental genotypes at more than one locus per chromosome might be partly responsible for the reduction of the estimated male map length.
