CYTOPLASMIC-NUCLEAR MALE-STERILITY IN PEARL-MILLET - COMPARATIVE RFLPAND TRANSCRIPT ANALYSES OF ISONUCLEAR MALE-STERILE LINES

The identification of diagnostic cytoplasmic molecular markers is of p rime interest to pearl millet breeders wishing to identify sources of cytoplasmic-nuclear male sterility (CMS) which can be used as an alter native to the single source currently used in the production of F-1 hy brid seed. Here, we report the classification of five pearl millet CMS sources based on RFLP analysis of isonuclear lines carried out using mitochondrial gene-specific DNA probes in combination with eight restr iction endonucleases. On the basis of RFLP data, the five CMS cytoplas ms can be distinguished from each other and from the isonuclear fertil e cytoplasm. In addition, based on cox1, cox3, atp6 and atp9 polymorph isms, these lines can be classified into two major groups: one corresp onds to A(5), A(egp), A(v) and A(1) cytoplasms, and the other consists of the A(4) cytoplasm. Our results suggest that a rearrangement invol ving the cox1 gene might be related to CMS in the first group (A(5), A (egp), A(v) and A(1)), whereas a rearrangement within the atp6/cox3 cl uster region might be related to CMS in the second group (A(4)).