RFLP DETECTION OF 2N POLLEN FORMATION BY FIRST AND 2ND DIVISION RESTITUTION IN PERENNIAL RYEGRASS

Unreduced gametes can be used to transfer desirable traits from parent to polyploid offspring. Codominant restriction fragment length polymo rphism (RFLP) markers were applied to determine the mechanism of 2n po llen formation in diploid (2n = 2x = 14) Lolium perenne L. Sixty heter ologous probes were randomly chosen from a Festuca arundinacea Schreb. PstI-genomic DNA library, A total of 30 and 33 heterozygous allelic l oci were detected in two genotypes of parental L. perenne, respectivel y, based on segregation of RFLP loci in 13 triploid (3x) and two tetra ploid (4x) hybrids, produced in 1993, between diploid L. perenne and t etraploid F. mairei St. Yves. Approximately 30 and 83% of the heterozy gosity was transmitted by 2n pollen from L. perenne into two tetraploi d hybrids, respectively. Both meiotic first division restitution (FDR) and second division restitution (SDR) occurred in 2n pollen formation in L. perenne. Omission of the second meiotic division (OS) and fusio n of adjacent polar nuclei (FA) were found during microsporogenesis, T hese two mechanisms were supposedly responsible for forming 2n gametes by SDR and FDR, respectively, Formation of 2n pollen in diploid L. pe renne could facilitate efficient transfer of germplasm from diploid to higher ploidy levels in Lolium and Festuca.