Plant Science Innovation, Center for

 

Date of this Version

10-1996

Comments

Published in Proc. Natl. Acad. Sci. USA Vol. 93, pp. 11763-11768, October 1996. Copyright 1996 National Academy of Sciences. Used by permission.

Abstract

In higher plants, dominant mitochondrial mutations are associated with pollen sterility. This phenomenon is known as cytoplasmic male sterility (CMS). It is thought that the disruption in pollen development is a consequence of mitochondrial dysfunction. To provide definitive evidence that expression of an abnormal mitochondrial gene can interrupt pollen development, a CMS-associated mitochondrial DNA sequence from common bean, orf239, was introduced into the tobacco nuclear genome. Several transformants containing the orf239M gene constructs, with or without a mitochondrial targeting sequence, exhibited a semisterile or male-sterile phenotype. Expression of the gene fusions in transformed anthers was confirmed using RNA gel blotting, ELISA, and light and electron microscopic immunocytochemistry. Immunocytological analysis showed that the 0RF239 protein could associate with the cell wall of aberrant developing microspores. This pattern of extracellular localization was earlier observed in the CMS common bean line containing orf239 in the mitochondrial genome. Results presented here demonstrate that 0RF239 causes pollen disruption in transgenic tobacco plants and may do so without targeting of the protein to the mitochondrion.

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