Chloroplast ultrastructure studies of the etched mutant

The virescent seedlings of et et (virescent) and normal genotypes were grown under light (1 w/m2) at 25 C and leaves were harvested six days after germination and processed for transmission electron microscopy. The mutant leaves show a poorly developed chloroplast ultrastructure compared to normal (Fig. 1). The internal membrane structure of the mutant chloroplast is significantly affected and the grana are less numerous than the normal chloroplast. Further, it was found that there were fewer discs per granum in the mutant chloroplast. On the contrary, chloroplasts from the normal leaf preparations show no such defects and exhibit normal ultrastructural development and differentiation (Fig. 1). These observations are in agreement with our earlier data (Ramesh, Kumari and Reddy, Biochem. International 1984) showing pigment deficiencies in the 6-day old mutant seedlings grown under light.

Figure 1. Chloroplasts prepared from leaf samples of six day old seedlings grown under light 1 w/m 2 ) at 25 C. A and B, mutant (et et) chloroplasts from virescent seedlings showing poorly developed grana, membranes and abnormal amoeboid shape. C, normal chloroplasts from normal seedlings showing well-developed internal structures and membranes (X 20,000).

S. V. Ramesh1 and A. R. Reddy

1Dept. of Biology, Univ. of Utah, Salt Lake City, Utah


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