Gametophytic degradation of CENH3 - a synthetic biology approach for haploid induction in plants

Double haploid technology is a critical tool for accelerating plant breeding. The manipulation of centromere-specific histone H3 (CENH3) has previously been shown to induce haploid progeny in both the model plant Arabidopsis and certain crop species. However, a universally applicable strategy for CENH3-based haploid induction across diverse crop species is still lacking. Here, we demonstrate that extreme asymmetry in centromeric CENH3 levels between parental chromosomes is a causal factor for eliminating chromosomes with ‘weaker’ centromeres during early embryogenesis. Consequently, engineered E3-ligases were utilized to selectively degrade CENH3 in the egg cell to induce wild-type paternal haploids. Also, we attempted to optimize the CENH3 degradation using E3-ligases of plant-origin. Our findings provide valuable insights to enhance the haploid induction efficiency further. The gametophytic CENH3 degradation approach leverages engineering principles and represents a potentially universal strategy for engineering CENH3-based haploid inducers in crop plants.