Haplodiploidization of maize (Zea mays L) through induced gynogenesis assisted by glossy markers and its use in breeding.

摘要

Reliable detection of haploids at the seedling stage is a prerequisite for the use of haplodiploidization through in situ gynogenesis in maize breeding. Recessive alleles of glossy (gl) genes, which suppress the formation of epicuticular waxes, wereused as markers to detect haploid seedlings. Two synthetic varieties with a broad genetic base, flint gl1 (CGT) and dent gl6 (DGT), were pollinated with the inducing strain FIGH1, and produced haploid seedlings at a rate of 0.64 and 0.93%, respectively.The rate of haploidization in S1 progenies was increased (0.94% on average) after selfing of the CGT (C0) synthetic line. Distribution of haploids within 203 S1 families showed a significant deviation in comparison with a Poisson distribution. The DGT synthetic showed an increase in haploid induction rate when a new synthetic was formed with doubled haploid (DH) lines, suggesting that inducibility may have some genetic effects. No spontaneous doubling was shown by the haploid seedlings produced from either synthetic line. Colchicine treatment allowed a recovery of male fertility in 30 to 60% of detected haploids. The progeny recovery rate from DGT synthetics was higher than that from CGT synthetics. The growing period also had an influence upon the recovery of fertile ears, as sowing at the beginning of spring was less detrimental for pre- and post-floral stages. Hybrids produced from heterotic DH lines showed agronomic potential similar to standard hybrids. Glossy recessive alleles gl1 and gl6 can therefore be used to detect haploids in the absence of a dominant marker in the inducing line, and without affecting yields in DH lines.