Transcriptomic analyses reveal regulatory plasticity and metabolic reprogramming underlying genotype-specific...

Area of Science:

• Plant Science
• Genetics
• Epigenetics

Background:

• Microspore embryogenesis induces immature male gametophytes to form embryo-like structures, crucial for doubled haploid (DH) plant regeneration.
• DH technology accelerates crop breeding by achieving complete homozygosity in one generation, vital for developing resilient wheat cultivars.
• Bread wheat's recalcitrance to microspore embryogenesis, linked to genotype dependence, hinders its widespread use in breeding programs.

Purpose of the Study:

• To investigate the molecular mechanisms underlying contrasting microspore embryogenesis responses in two spring wheat cultivars.
• To identify key genetic and epigenetic factors influencing wheat microspore embryogenesis efficiency.
• To discover potential biomarkers for overcoming recalcitrance in wheat DH breeding.

Main Methods:

• Comparative transcriptomic time-course analysis of two spring wheat cultivars (Nanda: highly responsive, Sadash: recalcitrant).
• Identification of differentially expressed genes (DEGs) and hotspots associated with embryogenic responses.
• Machine learning analysis to identify potential biomarkers and subgenome-specific expression patterns.

Main Results:

• Successful microspore embryogenesis in wheat involves dynamic gene expression reprogramming, with enriched epigenetic regulation processes in responsive genotypes.
• Coordinated changes in genes related to stress perception, hormonal signaling, cell wall dynamics, and metabolism characterize successful embryogenesis.
• Genotype-specific genomic variation and homoeolog expression bias, particularly B-subgenome suppression in recalcitrant lines, significantly impact embryogenic efficiency.

Conclusions:

• Epigenetic regulation, homoeolog expression bias, and genotype-specific genomic variation are key drivers of wheat microspore embryogenesis efficiency.
• Coordinated remodeling of metabolic and cell-wall pathways creates a favorable cellular environment for embryogenesis.
• Candidate molecular targets and biomarkers identified can aid in overcoming recalcitrance and enhancing wheat DH breeding.