About the Cover
On the Cover: Naturally occurring cytoplasmic male sterility (CMS) has been known for more than 100 years. CMS systems are used to produce commercial F1 hybrid lines. Ruiz and Daniell (pp. 1232-1246) report the first engineered CMS system in plants. They studied the effect of light regulation of the phaA gene coding for b-kethiolase engineered via the chloroplast genome. The phaA gene was efficiently transcribed and translated in all tissue types examined, including leaves, flowers, and anthers. The transgenic lines were normal except for the male-sterile phenotype, lacking pollen. Scanning electron microscopy revealed a collapsed morphology of the pollen grains. Transgenic lines showed an accelerated pattern of anther development, affecting their maturation, and resulted in aberrant tissue patterns. Abnormal thickening of the outer wall, enlarged endothecium, and vacuolation decreased the inner space of the locules, affected pollen grain, and resulted in the irregular shape or collapsed phenotype. Reversibility of the male-sterile phenotype was observed under continuous illumination, resulting in viable pollen and copious amount of seeds. This study offers a new tool for transgene containment for both nuclear and organelle genomes and provides an expedient mechanism for F1 hybrid seed production.
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Copyright © 2007 by the American Society of Plant Biologists
