ESTIMATION OF 2N MEGAGAMETOPHYTE HETEROZYGOSITY IN A DIPLOID BLUEBERRY (VACCINIUM-DARROWI CAMP) CLONE USING RAPDS

To determine the mode(s) of 2n gamete formation in a Vaccinium darrowi Camp (2n = 2x = 24) clone Fla4B, the transmission of parental heteroz ygosity was estimated in 2n eggs through randomly amplified polymorphi c DNA (RAPD) analysis of 41 progeny from crosses of Fla4B to tetraploi d V. corymbosum (2n = 4x = 48). The level of estimated heterozygosity transmitted ranged from 5.3-100%, with an overall mean heterozygosity of 72.7%, which suggests that first division restitution (FDR) type 2n gamete forming mechanisms are operating in this clone, However, there was evidence that 17% of the 2n eggs had less than 50% estimated hete rozygosity, which supports second division restitution (SDR) mechanism s operating as well, Both SDR and FDR modes of 2n egg formation are al so supported by a nonnormal, bimodal frequency distribution of estimat ed heterozygosity transmission, Recombination also appears to be preva lent. The predominance of 2n gametes genetically equivalent to FDR is generally considered desirable for breeding autotetraploid crops.