Characterization of Apomictic BC7 and BC8 Pearl Millet: Meiotic Chromosome Behavior and Construction of an ASGR-carrier Chromosome-specific Library
2010
Singh, M. | Conner, J.A. | Zeng, Y.-J. | Hanna, W. W. | Johnson, V. E. | Ozias-Akins, P.
Apospory in Pennisetum squamulatum Fresen is inherited as a single-locus dominant trait. Molecular analysis has identified the apospory-specific genomic region (ASGR), a large segment of one chromosome that is necessary and sufficient to confer apomixis. To transfer apospory from P. squamulatum to pearl millet [P. glaucum (L.) R. Br.], advanced backcrosses were generated. Here we report the characterization of apomictic BC₇ and BC₈ generations. A BC₇–derived genotype has two P. squamulatum chromosomes, while BC₈–derived apomictic lines inherited only the ASGR chromosome that confers apospory to pearl millet. Morphologically, no significant differences were observed between backcross generations for plant height, leaf length, leaf width, and first internode and inflorescence lengths. However, the BC₇ and BC₈ lines differed significantly with regard to pollen viability, flowering time, and seed set. Pollen viability increased to 81% in the BC₈ lines compared with 37% in BC₇ The frequency of aposporous embryo sacs was lower in BC₈ (79%) lines compared to BC₇ (93%). Meiotic behavior of chromosomes during metaphase I and anaphase I showed that BC₈ typically had a single univalent, identified as the ASGR chromosome by FISH (fluorescence in situ hybridization) and GISH (genomic in situ hybridization). Utilizing its unique behavior during meiosis the ASGR chromosome was microdissected and a chromosome-specific library was constructed and sequenced. Analysis of sequences identified both novel and previously known ASGR-linked sequences.
Show more [+] Less [-]AGROVOC Keywords
Bibliographic information
This bibliographic record has been provided by National Agricultural Library