Diversity Assessment in the In Vitro Conservation Response of Philippine Yam (Dioscorea Species) Accessions

Abstract

The National Plant Genetic Resources Laboratory maintains the largest in vitro germplasm collection of Dioscorea in the Philippines and has remained steadfast in its aim to safeguard accessions with potential use. Due to costly and time-consuming operations, most gene banks operate with the guidance of diversity assessments to measure the genetic integrity of one’s collection and design appropriate protocols for conservation. Diversity assessment under in vitro conditions remains unexplored even with the advantages of increased security and functionality in limited spaces. This study aimed to assess the genetic diversity of the in vitro conservation response of yam germplasm collection of the country. Four Dioscorea species totaling 217 accessions were subjected to in vitro culture conditions. Parameters such as % surviving cultures, % shoot regeneration, and degree of tissue browning were analyzed using the Shannon-Weaver diversity index and cluster analysis. Assessment of initial culture establishment and regeneration responses revealed a high degree of variability. D. alata had the highest response in % surviving cultures and % shoot regeneration. Diversity analysis using the Shannon-Weaver index revealed high diversity among the species and differences in diversity within species. This high level of diversity can be attributed to the distribution of responses observed in the accessions of each species. This high genetic diversity observed in the in vitro cultured Dioscorea indicates the necessity for the development of several in vitro culture protocols to obtain optimum responses for regeneration, conservation, and other in vitro applications.