Chaikam V, Nair SK, Martinez L, Lopez LA, Utz HF, Melchinger AE and Boddupalli PM (2018) Marker-Assisted Breeding of Improved Maternal Haploid Inducers in Maize for the Tropical/Subtropical Regions.

Front. Plant Sci. 9:1527. doi: 10.3389/fpls.2018.01527

Abstract : Through in vivo induction of haploids and subsequent chromosomal doubling, genetically homozygous breeding lines called double haploid (DH) lines can be produced in maize in just two crop seasons compared to the traditional inbreeding approach that requires 6–9 crop seasons. Until recently, there were no tropical haploid inducers in maize with high haploid induction rates and acceptable agronomic performance. This study presents how second-generation Tropically Adapted Inducer Lines (2GTAILs) were developed using marker assisted selection (MAS) for qhir1, a QTL with a significant positive effect on High haploid Induction Rate (HIR) from the crosses between elite tropical maize inbreds and first generation Tropically Adapted Inducers Lines (TAILs). One of the new inducers 2GTAIL006 showed an average HIR of 13.1% which is 48.9% higher than the average HIR of the TAILs. The number of plants of a source population that need to be crossed to obtain a desired number of haploids can be reduced by 41.6% compared to the first-generation haploid. This leads to considerable maize breeding costs savings.