As reported previously (MGCNL 51:55-59) several photosynthesis mutants selected on the basis of high chlorophyll fluorescence have been located to chromosome arm by crossing with stocks bearing B-A translocations. Below is an amended and expanded list of markers located to date:
New additions include arm locations for hcf*-12, hcf*-41 and hcf*-46. Previously, hcf*-2 was found to be uncovered by TB-1La-5S8041 and hcf*-3 was uncovered by TB-1Sb-2L4464; further crossing with simple translocations gave uncovering by TB-1La and TB-1Sb respectively. Repeated crossing of families segregating hcf* and hcf*-15 by known TB-1Sb failed to uncover high fluorescent seedlings, strongly suggesting that these loci are located on chromosome 2L. Some ambiguity remains however, due to the failure to complete sib tests for the hcf marker stocks. Allelism tests among several hcf loci were reported in MGCNL 51:57-59. This list has also been expanded:
These findings suggest that mutations at genetically distinct nuclear loci can cause very similar changes at the level of the chloroplast. This is especially evident in the case of the photosystem II mutants listed above, all of which show similar blocks in the function and organization of photosystem II.
Facilities and materials provided by M. G. Neuffer, E. H. Coe, J. Beckett and C. J. Arntzen are gratefully acknowledged (this work was supported by NSF grant PCM 76-08831 to DM).
Kenneth Leto* and Donald Miles
*Present address: Botany Dept.,
Univ. of Illinois, Urbana, IL 61801
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