THE PLANT CELL, Vol 6, Issue 1 85-91, Copyright © 1994 by American Society of Plant Biologists
Tissue-Specific Protein Expression in Plant Mitochondria
C. A. Conley and M. R. Hanson
Section of Genetics and Development, Biotechnology Building, Cornell University, Ithaca, New York 14853-2703
Although the physiological role of plant mitochondria is thought to vary in
different tissues at progressive stages of development, there has been
little documentation that the complement of mitochondrial proteins is
altered in different plant organs. Because the phenomenon of cytoplasmic
male sterility suggests an unusual function for mitochondria in floral
buds, we examined the tissue-specific expression of mitochondrial proteins
in petunia buds at several stages of development, using both fertile and
cytoplasmic male sterile plants. On tissue prints of cryostat-sectioned
buds, antibodies recognizing subunit A of the mitochondrial ATPase (ATPA)
localized very differently from antibodies recognizing subunit II of the
cytochrome oxidase (COXII), which indicated that mitochondria in the same
tissue could differentially express mitochondrially encoded proteins. The
petunia cytoplasmic male sterility-associated fused (pcf) gene encodes a
protein that colocalized with ATPA and the nuclear-encoded mitochondrial
alternative oxidase (AOA) in sporogenous tissues, where little COXII
protein was found. These overlapping and differential localization patterns
may provide clues to the molecular mechanism of cytoplasmic male sterility.
