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 in three amo ng 20 regenerants from callus cultures obtained from the panicle fragm ents of the sorghum plant with cytoplasmic male sterility. Induced fer tility is retained under self-pollination for eight generations. The p ollen fertility level in every generation varies in different plants ( 0-70%) and depends on the environmental factors, rather than on plant genotype. A high positive correlation (r = 0.90; P<0.01) has been reve aled between the pollen fertility level and the total rain precipitati on during the microgametophytogenesis. Cytoembryological investigation of this line has shown the presence of structures similar to aposporo us embryo sacs (ESs), which have developed in the ovules along with th e sexual ESs. The ovules with aposporous formations have been observed almost in all of the studied plants in several generations, however, their frequency varied (2-53%). Parthenogenetic proembryos and endospe rm nuclei without signs of pollen tube penetration have been found in some of such ESs. The nature of the instability observed in a number o f generations in male and female generative structures is discussed. ( C) 1995 Annals of Botany Company