Crossability and characterization of interspecific hybrids between sexual Pennisetum glaucum (pearl millet) and a new cytotype (2n=56) of apomictic P. squamulatum

Abstract

Pennisetum squamulatum is an important species belonging to tertiary gene pool of cultivated pearl millet as potential donor of several genes. Recently a new cytotype with 2n=56 chromosmes has been identified. Crossability of this cytotype has been studied with diploid and induced tetraploid pearl millet. The hybrids produced with this novel cytotype were compared for their characteristics with the hybrids previously reported with widely reported 2n=54 P. squamulatum cytotypes. Strong incompatability barriers were observed between 2n=56 cytotype with diploid pearl millet, and hybrids could not be obtained even after embryo rescue. Limited crossability was obtained with tetraploid pearl millet and 2 successful hybrids were produced. Their hybridity was confirmed by morphology, flowcytometry and cytology. The hybrids were highly fertile, perennial and segregated for mode of reproduction. Segregation for other traits confirmed heterozygous nature of P. squamulatum 2n=56 cytotype. Cytological investigations suggested 2n=8x nature of this cytotype. Successful hybridization between pearl millet and this new cytotype shall be important for introgression of useful traits as well as to study inheritance of traits such as perenniality, apomixis and tolerance to stresses. © 2007 The Japan Mendel Society.