Cytological and physiological changes in orthodox maize embryos during cryopreservation

Area of Science:

• Plant Science
• Cryobiology
• Biotechnology

Background:

• Cryopreservation is vital for preserving plant genetic resources.
• Maize embryos undergo significant cellular changes during cryopreservation.

Purpose of the Study:

• To investigate cytological and physiological alterations in maize embryos during cryopreservation.
• To correlate cellular damage with embryo viability post-cryopreservation.

Main Methods:

• Maize embryos at 35 days after pollination (DAP) were subjected to dehydration and freezing.
• Cytological damage, membrane integrity, electrolyte leakage, antioxidant enzyme activity, and lipid peroxidation were assessed.

Main Results:

• Dehydration and freezing induced plasmolysis, mitochondrial swelling, and nuclear changes.
• Plasma membrane integrity was compromised, especially at moisture content above 23% post-freezing.
• Antioxidant enzyme activities (APX, GR, SOD, DHAR, CAT) showed varied responses to cryopreservation stress.
• Membrane lipid peroxidation increased significantly, but embryo viability correlated with ultrastructural damage, not directly with antioxidant or lipid peroxidation levels.

Conclusions:

• Cryopreservation induces substantial cellular damage in maize embryos.
• Embryo viability is primarily linked to structural integrity rather than specific biochemical markers like antioxidant levels or lipid peroxidation.