The Management Committee of the Environmental Futures Centre would like to congratulate Dr Adam Kaity on his recent PhD attainment. The topic of Adam's research was the Genetic, Epigenetic and Morphological Evaluation of the Effects of Cryopreservation on Papaya. Adam was supervised by Dr Sarah Ashmore and Professor Rod Drew from the School of Biomolecular and Physical Sciences.
Abstract
A vitrification-based cryopreservation technique for storage of in vitro papaya shoot tips was tested to ensure applicability across a range of genotypes and to assess the stability of both genotype and phenotype of clonal material following one hour to 18 months of cryo-storage. This investigation is the first report of field performance and evaluation of mature papaya morphological traits following cryopreservation. Genomic DNA structure was analysed using PCR based randomly amplified DNA fingerprinting and DNA methylation patterns were examined using the amplified DNA methylation polymorphism approach. The regenerated plants showed varying levels of DNA and methylation modifications between the genotypes, indicating some genotype dependent variability following cryopreservation could result in somaclonal variation.
Analysis of plants regenerated from control and cryopreservation treatments showed that variations can occur in untreated in vitro controls resulting from routine micropropagation, and suggested that cryoprotective pre-treatment and freezing in liquid nitrogen may not cause further somaclonal variation. The variations were not correlated to phenotypic characteristics two months after acclimatisation suggesting variations occurred in non-coding loci. The investigations demonstrated the suitability of the cryopreservation protocol for application to in vitro gene banks which are vital in securely maintaining genetic diversity through germplasm conservation.