ISOZYME, PROTEIN, AND RAPD MARKERS WITHIN A HALF-SIB FAMILY OF BUFFELGRASS SEGREGATING FOR APOSPORY

Isolation of genes controlling apomixis would be useful to plant breed ers for fixing hybrid vigor. A single gene codes for aposporous apomix is in buffelgrass [Pennisetum ciliare (L.) Link]. This study was under taken to assess the feasibility of using isozyme, protein, and random amplified polymorphic DNA (RAPD) markers to detect apospory-linked seq uences within a segregating half-sib population, Sexual plant B-2s, fi ve sexual and three aposporous progeny of sexual B-2s, and cultivar Hi ggins were studied, Floret and leaf proteins were separated by starch gel electrophoresis, and enzymes in the gel were stained to detect iso zyme polymorphisms. Of 22 isozyme systems tested, 12 showed polymorphi sms but none cosegregated with apomixis, Two-dimensional polyacrylamid e gel electrophoresis was used to separate steady state proteins of pi stils at meiotic and post-meiotic stages. This technique revealed appr oximate to 12% polymorphism within 308 spots, but none of the spots co segregated with reproductive mode, Genomic DNA was screened for RAPD m arkers with 111 10-mer random primers and polymerase chain reaction, O f 569 markers identified, 87% were polymorphic. One marker cosegregate d with sexual lines, but none cosegregated with aposporous lines, Anal ysis of molecular variance examination of the B-2s parent and the eigh t half-sib progeny (Higgins excluded) showed that on the basis of 404 RAPD markers, the aposporous and sexual groups were not significantly different. No RAPD markers were tightly linked with apospory. Addition al screening of new primers will allow identification of markers for t he gene in full-sib families.