The Application of Ooubled Haploid Plants to Population ... - MSpace

ABSTRACT
Production of doubled haploid (DH) plants has been used as a tool to shorten the time
frame of population improvement in several seFpollinating species. ln BWta rapa,
the production of OH plants leads to inbreeding depression and therefore diminishes
their usefulness. This study examined the ability of random amplified polyrnorphic DNA
(RAPD) to detect genetic variation among DH Iines produced from B. rapa populations.
RAPD analysis was perfonned on DH lines and composite populations developed after
two generations of outcroçsing within a collection of 4,8,12 and 22 individual DH lines.
RAPD analysis detected 40 to 83% polymorphic bands between the OH Iines using five
oligonucleotide primers. RAPD analysis detected 1743% and 27-47% polyrnorphic
bands in the first composite and second composite populations, respedively. The
highest level of genetic variation was shown by the composite population produced
from 22 DH lines. RAPO analysis efficiently characterized Vie genotypic variation
present in DH and composite populations. RAPD analysis may be useful as a tool in
the reestablishrnent of heterogeneity and recovery of agronomie performance in B. rapa
composite populations derived from OH lines by diaractetizing the level of genetic
variability among DH lines and detemining optimal population size.
Key words: Brassica rapa, genetic variation, heterosis, PCR, RAPD