Cytoplasmic Male Sterility in Barley : VIII. LIPOXYGENASE ACTIVITY AND ANTHER AMINO NITROGEN IN THE msm1-Rfm1a SYSTEM.

The lipoxygenase (LOX) activity was determined in almost isogenic types of barley (Hordeum vulgare L.): normal cv. Adorra, cytoplasmic male sterile (msm1), and msm1 barley with restored fertility, heterozygous for the Rfm1a restorer gene. The LOX activity was lowest in male steriles in the leaf tissue studied at the anthesis stage. The LOX activity in developing anthers was higher than in leaf tissue, and decreased during degeneration of the sterile anthers.On polyacrylamide gel electrophoresis slabs, the LOX of anther homogenates moved in a complex which evidently carried some lipid and pigment, too. The LOX zones showed pseudoisoenzymic movement, i.e. a gradual increase in mobility dependent on the age of the anthers. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis slabs, the LOX zones contained three polypeptides. When sporopollenin production ends in the fertile anthers, a fourth polypeptide (molecular weight 91,200) appears in their LOX zones. This ;late' polypeptide is missing from steriles, and is suggested as being associated with the termination of sporopollenin production in the tapetum of fertiles.Sterile anthers were found to be almost devoid of soluble NH(2)-N, which supports the idea of their starvation. This starvation can reasonably be held responsible for the absence of late proteins (e.g. the 91,200 dalton polypeptide), and is reinforced by the uncontrolled production of sporopollenin.