ISSN:
0192-253X
Keywords:
maize
;
mitochondrial DNA
;
recombinant DNA
;
Life and Medical Sciences
;
Genetics
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
Twenty-eight Bam H 1 restriction fragments were isolated from normal mitochondrial DNA of maize by recombinant DNA techniques to investigate the organization of the mitochondrial genome. Each cloned fragment was tested by molecular hybridization against a Bam digest of total mitochondrial DNA. Using Southern transfers, we identified the normal fragment of origin for d each clone. Twenty-three of the tested clones hybridized only to the fragment from which the clone was derived. In five cases, labeling of an additional band indicated some sequence repetition in the mitochondrial genome. Four clones from normal mitochondrial DNA were found which share sequences with the plasmid-like DNAs, S-1 and S-2, found in S male sterile cytoplasm. The total sequence complexity of the clones tested is 121×106 d (daltons), which approximates two thirds of the total mitochondrial genome (estimated at 183×106 d).Most fragments do not share homology with other fragments, and the total length of unique fragments exceeds that of the largest circular molecules observed. Therefore, the different size classes of circular molecules most likely represent genetically discrete chromosomes in a complex organelle genome. The variable abundance of different mitochondrial chromosomes is of special interest because it represents an unusual mechanism for the control of gene expression by regulation of gene copy number. This mechanism may play an important role in metabolism or biogenesis of mitochondria in the development of higher plants.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/dvg.1020010409
