Albinism in Cereal Androgenesis-Shedding Light on Molecular Mechanisms and Possible Solutions.

Albinism is a major limitation in androgenesis-based doubled haploid (DH) production in cereals, significantly limiting the efficiency of this powerful breeding tool. Albino plantlets, which do not develop functional chloroplasts, are unable to photosynthesize and thus cannot survive outside of in vitro culture. Despite numerous attempts to optimize androgenesis protocols, albinism remains difficult to eliminate, largely due to its strong genotype dependence. Recent studies have shed light on the molecular and cellular mechanisms underlying this phenomenon, linking it to early plastid differentiation during in vivo pollen development, plastid DNA instability, and disrupted chloroplast biogenesis. Premature activation of starch biosynthesis and amyloplast formation in microspores has been correlated with high rates of albino regeneration. This chapter summarizes key advances in understanding the developmental and genetic basis of albinism in androgenesis, focusing on plastid biology, regulation of transcription, and developmental checkpoints during chloroplast differentiation. Promising strategies, including utilization of early-mid uninucleate microspores to initiate androgenesis are discussed as potential solutions to overcome genotype-dependent albinism in cereals.