Studies of growth & metabolism of a barley mutant lacking chlorophyll b.

In an earlier paper (7) the chlorophyll composition of a number of chlorina mutants of barley obtained from D. W. Robertson (10) were described and it was then pointed out that one of the mutants appeared to be entirely lacking in chlorophyll b. Thus, it was of considerable interest to learn whether the chlorophyll b deficiency was affecting the photosynthetic activity of this mutant. Comparative studies on the photosynthetic activities in white light of the normal type (containing chlorophyll a & b) and of the mutant as well as studies on their respiratory behavior in the dark and in the light are reported here. In addition, some effort has been made to ascertain whether chlorophyll b could possibly be detectedl in the chlorophyll b deficient mutant by means of the more sensitive fluorescence analysis of chromatographed pigment extracts. Chlorophyll b dleficient mutants in higher plants first were described by Eyster (4) in maize and more recelntly by Robbelen (9) in Arabi(lopsis. However, the plants described by these investigators (lid not survive the seedling stage-dying rather early in their life cycles. In contrast, the barley mutant employed in the investigations described here can complete its life cycle and thus should be of considerable usefulness in continuied investigations on the role of chlorophyll b in the photo-mletabolismii of higher plants.