barnase

A bacterial ribonuclease, which, when transformed into plants and expressed in the anthers, generates a male sterile phenotype. Thus it is a technology applicable to F₁ hybrid seed production, which relies on the ability to genetically sterilize genotypes to ensure that all seed borne on the plant are the result of outcrossing. The sterility phenotype is suppressed by the barstar protein, which can therefore be used to reverse the sterility where this is necessary.