Partially Fertile Line with Apospory Obtained from Tissue Culture of Male Sterile Plant of Sorghum (Sorghum bicolor L. Moench)

A partial restoration of male fertility has been revealed inthree among 20 regenerants from callus cultures obtained fromthe panicle fragments of the sorghum plant with cytoplasmicmale sterility. Induced fertility is retained under self-pollinationfor eight generations. The pollen fertility level in every generationvaries in different plants (0-70%) and depends on the environmentalfactors, rather than on plant genotype. A high positive correlation(r = 0·90; P < 0·01) has been revealed betweenthe pollen fertility level and the total rain precipitationduring the microgametophytogenesis. Cytoembryological investigationof this line has shown the presence of structures similar toaposporous embryo sacs (ESs), which have developed in the ovulesalong with the sexual ESs. The ovules with aposporous formationshave been observed almost in all of the studied plants in severalgenerations, however, their frequency varied (2-53%). Parthenogeneticproembryos and endosperm nuclei without signs of pollen tubepenetration have been found in some of such ESs. The natureof the instability observed in a number of generations in maleand female generative structures is discussed.Copyright 1995,1999 Academic Press Cytoplasmic male sterility, fertile revertants, apomixis, somaclonal variability, Sorghum bicolor L. (Moench)