Microanalysis of plant mitochondrial protein synthesis products: : Detection of variant polypeptides associated with cytoplasmic male sterility.

A mitochondrial fraction obtained from 0.5 g of leaves was purified on a 0.75 ml Percoll gradient and used for an in vitro mitochondrial protein synthesis assay in the presence of [(35)S] methionine. A set of 15 to 20 labeled polypeptides were revealed by autoradiography after sodium dodecylsulfate polyacrylamide gel electrophoresis. This could be applied at an early growth stage by using a few leaves from individual seedlings. It revealed the presence of variant mitochondrially translated polypeptides in green leaves of cytoplasmic male sterile lines from various cultivated plants of large economic importance: maize, wheat, sugar beet, tobacco and faba bean. This non-destructive microanalysis is thus of general use and opens new possibilities for rapid and large mass screening of mitochondrial parameters such as male sterility.