Abstract

Charity Chidzanga, Faith Muzawazi, Joanah Midzi, Tendai Hove

Haploids and doubled haploids (DH) have become effective tools in maize genetics and breeding. The DH technology is replacing the conventional method of line development and speeding up the process of obtaining new varieties. Numerous maize DH based inbred lines and hybrids have been developed and released around the world. Temperate maize breeding programs have taken the lead in adopting the DH technology while in the tropical maize breeding uptake is still hampered by limited awareness of the potential and applicability of the technology. There are various methods for haploid induction, identification of putative haploids and chromosome doubling. However the effective and efficient large scale use of the DH technology depends on the most effective, sustainable and efficient methods of haploid induction, identification of putative haploids and chromosome doubling. The most commonly used method for haploid induction is in vivo haploid induction of maternal haploids through the use of inducer lines. The R1-nj marker system for haploid identification and chromosome doubling through the use of various concentrations of colchicine are considered the most common methods of identifying putative haploids and chromosome doubling respectively. Herein, they reviewed (i) the various procedures available for DH production, (ii) the methods for identifying putative maize haploids (iii) chromosome doubling methods (iv) the genetic basis of in vivo haploid induction in maize and (v) the use of the DH technology in maize breeding.