Hazelnut Pollen Phenotyping Using Label-Free Impedance Flow Cytometry

Area of Science:

• Agricultural Science
• Plant Biology
• Cytogenetics

Background:

• Hazelnut (Corylus avellana) exhibits sporophytic self-incompatibility and can experience high pollen sterility due to reciprocal chromosome translocations.
• Understanding hazelnut pollen biology is crucial for agriculture and plant breeding, especially given its midwinter pollination under specific environmental conditions.

Purpose of the Study:

• To apply impedance flow cytometry (IFC) for the first time to characterize hazelnut pollen biology, including viability and sterility.
• To determine optimal pre-hydration conditions for accurate hazelnut pollen viability assessment.
• To evaluate pollen viability and sterility across various hazelnut cultivars and wild genotypes.

Main Methods:

• Impedance flow cytometry (IFC) was employed for label-free analysis of hazelnut pollen.
• IFC was validated using dye exclusion microscopy.
• Pollen hydration dynamics, viability, and sterility were assessed in 33 cultivars and two wild hazelnut accessions.

Main Results:

• Pollen sterility rates varied significantly among hazelnut accessions, with distinct groups of highly sterile and good-quality pollen producers.
• Optimal pollen hydration for viability assessment was achieved after approximately 6 hours of pre-hydration in humid chambers.
• Pollen viability measurements were strongly influenced by hydration levels, highlighting the importance of humidity for pollen functionality.

Conclusions:

• Impedance flow cytometry is a valuable tool for high-throughput phenotyping of hazelnut pollen.
• Reciprocal chromosome translocations likely contribute to gametic semi-sterility observed in certain hazelnut cultivars.
• Further research is needed to elucidate the causes of pollen sterility and its impact on hazelnut productivity.