Mitochondrial Plasmids in Sorghum: Presence of Linear Plasmids in Indian Male Sterile and Milo 296 Lines

The presence of plasmids of sizes 5.8 kbp, 5.3 kbp, 2.3 kbp, 1.7 kbp and 1.36 kbp was detected in 3 Indian male sterile cytotypes viz. Maldandi, Guntur, Vizianagaram but not in their fertile maintainer lines. The 5.8 kbp and 5.3 kbp plasmids do not possess any homology with the nuclear or chloroplastic DNA as also with the main mitochondria) genome of sterile and maintainer fertile lines. The detection of these plasmids in the male sterile, maintainer fertile and fertility restored lines of 296 variety is surprising as the male sterile 296A and restored line possess a milo cytoplasm that has as yet not been shown to contain such plasmids. This observation suggests that plasmids have no role to play in male sterility but their presence could be used as a marker for characterization/classification of certain cytoplasms especially the Indian cytoplasms.