Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 10/15/1999
Publication Date: 1/15/2000
Technical Abstract: Information regarding apomixis at the gene, chromosome, and genome levels can be obtained from a comprehensive linkage study. The objective of this research was to construct an RFLP (Restriction Fragment Length Polymorphism) linkage map in apomictic buffelgrass (Pennisetum ciliare (L.) Link) using an F1 population segregating for method of reproduction. Cytological studies have shown buffelgrass to be a segmental allotetraploid; however, conflicting reports exist as to the genetic control of apomixis (disomic vs. tetrasomic) in this species. A total of 465 polymorphic probes from homologous and heterologous sources yielded separate maps for the female (sexual) and male (apomictic) parents with 47 and 42 linkage groups, respectively. The apomixis locus mapped to a single linkage group and was tightly linked with two homologous probes. Repulsion analyses suggested: 1) a single homolog for the apomixis linkage group, 2) preferential pairing in 55% versus 38% of linkage groups in the female and male parents, respectively, and 3) a higher recombination frequency in the female parent (48%) than the male parent (15%). Comparison of interval lengths in 15 allelic bridges supported the repulsion data and suggested significantly less recombination in the male parent. The implications of segmental allopolyploidy and suppressed recombination for cloning the apomixis gene(s) will be discussed.