Np. Schultes et al., Maize high chlorophyll fluorescent 60 mutation is caused by an Ac disruption of the gene encoding the chloroplast ribosomal small subunit protein 17, PLANT J, 21(4), 2000, pp. 317-327
The maize mutation high chlorophyll fluorescence 60-muTable 1 (hcf60-m1), g
enerated through Activator (Ac) tagging, has insufficient photosynthetic el
ectron transport. Here we show that the Hcf60 gene encodes a protein with s
ubstantial amino acid similarity to plant plastid and bacterial ribosomal s
mall subunit protein 17 (RPS17) proteins. The lack of detectable HCF60 tran
scripts in mutant leaves, and insertion of the transposed Ac element 17 bp
upstream of the start of translation in the mutated locus, suggest that lit
tle if any RPS17 is produced. The mutant phenotype is consistent with reduc
ed plastid translation. Seedling lethal hcf60-m1 plants display temperature
and light-dependent chlorophyll deficiencies, a depletion of plastid rRNA
pools, and few high-molecular-weight polysomal complexes. Growth under mode
rate light conditions (27 degrees C, 100 mu E m(-2) sec(-1)) allows for sub
stantial chlorophyll accumulation in mutant leaves, yet the number of funct
ional photosystem II complexes appears low. Nevertheless, the presence of a
limited but intact C-4 system indicates that some plastid translation occu
rs.