In a first step towards engineering male sterility in oilseed rape, a ribonuclease gene is combined with a regulatory DNA sequence, causing this gene to be expressed only during the early development of the anthers. Ribonuclease degrades RNA, which results in cell death. Consequently expression of this gene must be targeted solely to those cells giving rise to pollen.
At right is a normal oilseed rape flower from which petals and sepals have been dissected off to expose the stamens and pistils. At left is a transgenic rape plant containing an anther-specific ribonuclease gene. The stunted anthers are sterile and do not produce pollen. While these transgenic lines do not represent a commercially viable male sterile line, they demonstrate the feasibility of this approach.