Maize In Planta Haploid Inducer Lines: A Cornerstone for Doubled Haploid Technology

Area of Science:

• Plant breeding
• Genetics
• Agricultural biotechnology

Background:

• Doubled haploid (DH) technology accelerates crop improvement by creating homozygous lines.
• Traditional DH production relies on costly in vitro methods, but maize offers unique in planta systems.
• Maize haploid inducers, derived from spontaneous mutants, facilitate direct haploid embryo development in seeds.

Purpose of the Study:

• To review advancements in doubled haploid (DH) technology for maize breeding.
• To highlight the development of efficient in planta haploid induction systems in maize.
• To discuss novel applications and the translation of maize DH technology to other crops.

Main Methods:

• Utilizing spontaneous maize mutants as haploid inducer lines for paternal or maternal haploid production.
• Developing high-induction rate haploid inducers (8-12%) and kernel sorting methods.
• Investigating genomic loci involved in spontaneous chromosome doubling for in planta DH pipelines.

Main Results:

• Modern haploid inducer lines and efficient sorting methods enable large-scale DH production.
• Discovery of molecular players controlling haploid induction elucidates underlying mechanisms.
• Successful diversion of maternal haploid induction for genome editing in recalcitrant germplasm.

Conclusions:

• Maize DH technology has significantly advanced, enabling rapid breeding and trait evaluation.
• In planta DH systems in maize offer cost-effective and efficient haploid production.
• The understanding and application of haploid induction are expanding to other crop species.