ABSTRACT
The degree of genetic diversity within and between 21 Arabidopsis thaliana (L.) Heynh ecotypes was estimated by AFLP analysis. Within seven of the 21 ecotypes, a low but significant level of polymorphism was detected, and for five of these ecotypes two or three distinct subgroups could be distinguished. As these ecotypes represent natural populations, this intraecotypic diversity reflects natural genetic variation and diversification within the ecotypes. The source of this diversity remains unclear but is intriguing in view of the predominantly self-fertilizing nature of Arabidopsis. Interrelationships between the different ecotypes were estimated after AFLP fingerprinting using two enzyme combinations (EcoRI/MseI and SacI/MseI) and a number of selective primer pairs. SacI recognition sites are less evenly distributed in the genome than EcoRI sites, and occur more frequently in coding sequences. In most cases, AFLP data from only one enzyme combination are used for genetic diversity analysis. Our results show that the use of two enzyme combinations can result in significantly different classifications of the ecotypes both in cluster and ordination analysis. This difference most probably reflects differences in the genomic distribution of the AFLP fragments generated, depending on the enzymes and selective primers used. For closely related varieties, as in the case of Arabidopsis ecotypes, this can preclude reliable classification.
Subject(s)
Arabidopsis/classification , Arabidopsis/genetics , Genetic Variation , Phylogeny , Polymorphism, Genetic , DNA Fingerprinting , Deoxyribonuclease EcoRI , Deoxyribonucleases, Type II Site-Specific , Genotype , Geography , Restriction MappingSubject(s)
Arabidopsis/genetics , Chromosome Mapping/methods , Polymorphism, Restriction Fragment Length , Arabidopsis/physiology , Cloning, Molecular/methods , Crosses, Genetic , DNA, Plant/genetics , DNA, Plant/isolation & purification , Genes, Plant , Genes, Recessive , Genetic Linkage , Genetic Markers , MutationABSTRACT
A negatively photo-regulated gene (bcb) has been isolated by means of differential hybridization of a genomic library of Arabidopsis thaliana. In mature plants, a 20-fold increase in the amount of steady-state bcb mRNA can be detected upon 48 h of dark adaption. The expression level of the gene is also dependent upon the developmental stage of the plant. The 21.5-kDa gene product (BCB) shows extensive similarity with blue Cu(2+)-binding proteins such as plastocyanin and stellacyanin. The protein abundance increases only twofold upon dark adaption, which implies the presence of post-transcriptional control. The isolation of a novel negatively photoregulated gene allows us to investigate the complex expression profile of genes responding to the absence of light.
