The transgenic line MS1 (B91-4) was produced by genetically engineering plants to be male sterile and tolerant to the herbicide glufosinate ammonium (as a selectable marker). The parental line MS1 contains the barnase gene for male sterility, isolated from Bacillus amyloliquefaciens, a common soil bacterium that occurs naturally in the soil and in various organisms including bacteria and plants, and frequently used as a source for industrial enzymes. The barnase gene encodes for a ribonuclease enzyme (RNAse) expressed only in the tapetum cells of the pollen sac during anther development. The RNAse affects RNA production, disrupting normal cell functioning and arresting early anther development, thus leading to male sterility.

The transgenic line RF3 (DBN212-0005) was produced by genetically engineering plants to restore fertility in the hybrid line and to be tolerant to the herbicide glufosinate ammonium (as a selectable marker). Transgenic RF3 plants contain the barstar gene isolated from Bacillus amyloliquefaciens. The barstar gene codes for a ribonuclease inhibitor (barstar enzyme) that is expressed only in the tapetum cells of the pollen sac during anther development. The ribonuclease inhibitor specifically inhibits barnase RNAse expressed by the MS8 line. Together, the RNAse and the ribonuclease inhibitor form a very stable one-to-one complex, in which the RNAse is inactivated. As a result, when pollen from the restorer line RF3 is transferred to the male sterile line MS8, the resultant progeny express the RNAse inhibitor in the tapetum cells of the anthers allowing hybrid plants to develop normal anthers and restore fertility.