Q.63 Which one of the following methods is INCORRECT with respect to haploid plant
production? It can be produced
(A) from an unfertilized egg cell
(B) from nucellar tissue
(C) from isolated pollen culture
(D) by distant hybridization, followed by selective elimination of chromosomes of one of
the parents

Option (B) is the incorrect method for haploid plant production. Nucellar tissue is diploid and produces diploid embryos via nucellar embryony, not haploid plants.​

Option Analysis

(A) Unfertilized Egg Cell

Gynogenesis involves culturing unpollinated ovaries or ovules where the unfertilized egg cell (haploid) develops into a haploid embryo, a standard method for haploid production in crops like barley and rice.​

(B) Nucellar Tissue

Nucellar tissue in the ovule is diploid maternal tissue; embryos from it (nucellar embryony) are diploid clones of the mother plant, as seen in citrus, not haploid.​

(C) Isolated Pollen Culture

Androgenesis uses isolated pollen grains (haploid microspores) cultured to form haploid plants, refined from anther culture and effective in species like tobacco and wheat.​

(D) Distant Hybridization

Wide crosses cause selective chromosome elimination of one parent in the hybrid embryo, yielding haploid plants of the other parent, used in barley (bulbosum method) and wheat.​

Haploid plant production methods revolutionize breeding by creating homozygous lines quickly for genetics and crop improvement. Key techniques include gynogenesis from unfertilized egg cells, androgenesis via isolated pollen culture, and distant hybridization with chromosome elimination, but nucellar tissue does not yield haploids.​

Valid Techniques

• Gynogenesis (Unfertilized Egg): Haploid embryos form from female gametes in ovary cultures.​

• Pollen Culture (Androgenesis): Microspores develop into haploid plants in vitro.​

• Distant Hybridization: Eliminates one parent’s chromosomes post-crossing.​

Why Nucellar Tissue Fails

Nucellar embryony produces diploid apomictic embryos, not haploids, due to diploid sporophytic origin.​

CSIR NET Relevance

These methods appear in exams; doubled haploids from them speed variety development.