Wheatley, Andrew O.; Asemota, Helen N.; Ahmad, Mohammed H.
Author Affiliation, Ana.
Department of Basic Medical Sciences
A comparison of the storageability of in vitro derived and traditionally produced yam (Dioscorea cayenensis) tubers
Jamaican journal of science and technology
Date of Publication
The storageability of yam (Dioscorea spp.) tubers produced from tissue culture derived planting materials and traditionally produced tubers was examined. Tubers were stored at 27 ± 1°C on indoor shelves and 20 ± 1°C in the dark. The cell wall enzymes, pectin methylesterase (PME), polygalacturonase (PG) and cellulase were assayed during the storage period. To mimic the traditional practice of the removal of yam heads, in vitro derived tubers were also cut and stored at 27 ± 1°C on indoor shelves. We found that in vitro derived tubers stored better than traditionally produced tubers. Intact in vitro tubers at 27°C under ambient conditions did not sprout until the 14th week of storage as against the 5th week traditionally produced tubers. Storage of in vitro derived tubers at 20°C in the dark extended the storage life by 6-10 weeks. Traditionally produced tubers at 20°C in the dark stored up to the 14th week. Cutting of in vitro derived tubers and storing at ambient temperatures (27°C ) resulted in rotting after 13 weeks. PME increased sharply to a maximum in the tenth week of storage of in vitro derived tubers before decreasing toward the end of the study. Polygalacturonase began increasing when PME reached a maximum in the tenth week of storage and increased with further storage. A similar trend was observed for cellulase activity as seen for PG during storage. Cellulase remained constant up to the tenth week of storage, after which the enzyme activity increased sharply. This increase in cellulase activity continued with further storage. It would appear that the source of planting material influences the storageability of the resultant tubers and that the degradation of the cell wall during storage reflects some of the biochemical changes taking place.....