Chloroplast Ultra-structure of a Xantha Wheat Mutant

The chloroplast numbers,morphologies and ultra-structures in the leaves of a xantha wheat mutants etiolating naturally and its parent(Xinong1718) were comparatively examined by transmission electron microscopy.It was shown that the mutant plants with three etiolating degrees did not obviously differ in chloroplast distribution,number,shape and size from the mutant parent;(2) Yellowish-green plants whose chlorophyll content was 58% of the wild type did not obviously differed in chloroplast ultra-structure from the parent,but their stroma-thylakoids and granum-thylakoids were highly differentiated and their granum and grana lamellae were relatively plentiful;(3) The chlorophyll contents of the golden and greenish-yellow plants were separately 17% and 24% of that of the wild type and their chloroplast ultra-structures obviously differed from that of the parent and the chloroplasts of the mutant plants had clear developmental defect,the chloroplasts of golden plants containing no grana,obviously visible stroma lamellae,starch grains and plentiful osmiophilic granules and those of greenish-yellow mutant plants containing grana whose number was obviously lower than that in the chloroplasts of the parent and that had a fewer layers of stroma lamellae,and highly developed granum-thylakoids.The results indicted that the change in the chloroplast ultra-structure of the xantha wheat mutant resulted from lowered chlorophyll content and it was supposed that the etiolating mutation resulted from chlorophyll synthesis blockade.