Practice question

Androgenesis is male gametophyte-mediated haploid production pathway exploiting totipotency of immature pollen. Anthers containing uninucleate microspores at late uninucleate to early binucleate stage are excised and cultured on nutrient media, or isolated microspores are separated from anthers and cultured in liquid medium under stress. Developmental program of microspore shifts from pollen grain maturation toward sporophytic division, forming embryo-like structures or callus that regenerate haploid plantlets with n chromosomes derived entirely from paternal gametic genotype. Process exploits ability to switch from gametophytic to embryogenic pathway under stress treatments such as cold pretreatment, starvation, heat shock, and hormones auxin and cytokinin. Androgenic DH lines have been successful in rice, wheat, barley, tobacco, and pepper. Efficiency depends on genotype responsiveness, microspore stage precision, and anther wall influence, requiring optimization of media with sucrose and growth regulators for embryo induction and regeneration protocols. Androgenic response is regulated by embryogenic genes BBM, LEC1, SERK, and chromatin remodeling factors; stress induced reprogramming involves histone deacetylation, DNA demethylation, and auxin biosynthesis shift, converting microspore from gametophytic to sporophytic fate enabling efficient haploid embryo formation in responsive genotypes under optimized protocols.